Negli ultimi venti anni, nell'ambito di progetti di ricerca finanziati dalla Comunità Europea dalle agenzie spaziali nazionali ed internazionali (ASI, ESA,
NASA), sono state acquisite le seguenti competenze:
Radar ad Apertura Sintetica
(SAR) data processing;
Analisi di dati telerilevati nel campo VIS/NIR acquisiti da piattaforme satellitari per la misura di parametri chimici e biofisici per la qualità delle acque costiere;
Elaborazione di dati meteorologici e climatologici; servizi di previsione meteorlogica ad elevata risoluzione spazio-temporale;
Sviluppo di algoritmi di signal & image processing utilizzando linguaggi di programmazione compilati o di scripting
(MATLAB, SCILAB, IDL, C, C++) nonchè in Assembly;
Soluzioni informatiche per architetture parallele e di grid-computing.
Partendo da tale background scientifico, GAP intende fornire prodotti e servizi
caratterizzati da un elevato contenuto di innovazione e scientifico/tecnologico nel campo del remote sensing e delle correlate tecnologie HW/SW:
Produzione, marketing e customer service;
Studi di fattibilità, progettazione, sviluppo e prototipizzazione di procedure innovative per il digital signal processing (DSP)
dedicato in particolare a dati telerilevati satellitari;
Attività di formazione e training rivolte a tutti coloro che intendono affacciarsi alle tecnologie del telerilevamento;
Attività di ricerca e sviluppo per un aggiornamento continuo del know-how nei campi di nostro specifico interesse.
GAP contribuisce altresì all'organizzazione del Master in Tecnologie per il Telerilevamento Spaziale,
master universitario di II livello organizzato da Università di Bari e promosso da Università di Bari, Politenico di Bari, Agenzia Spaziale Italiana e eGEOS.
Qui di seguito riportiamo l'elenco dei lavori pubblicati da ricercatori del Gruppo di Telerilevamento del Dipartimento Interateneo di Fisica "M. Merlin" di Bari e/o dello spin-off GAP srl.
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[Col.RS2024] R. Colacicco, A. Refice, R. Nutricato, F. Bovenga, G. Caporusso, A. D’Addabbo, M. La Salandra, F. P. Lovergine, D. O. Nitti, D. Capolongo, "High-Resolution Flood Monitoring Based on Advanced Statistical Modeling of Sentinel-1 Multi-Temporal Stacks". Remote Sensing (Open Access) Volume 16, Issue 2, January 2024, Article number 294, ISSN: 20724292, DOI: 10.3390/rs16020294, Scopus: 2-s2.0-85183327302, WOS:001151313200001, IF(2023): 4.2, IF(5-Year): 4.9 (Source: MPDI).
High-resolution flood monitoring can be achieved relying on multi-temporal analysis of remote sensing SAR data, through the implementation of semi-automated systems. Exploiting a Bayesian inference framework, conditioned probabilities can be estimated for the presence of floodwater at each image location and each acquisition date. We developed a procedure for efficient monitoring of floodwaters from SAR data cubes, which adopts a statistical modelling framework for SAR backscatter time series over normally unflooded areas based on Gaussian processes (GPs), in order to highlight flood events as outliers, causing abrupt variations in the trends. We found that non-parametric time series modelling improves the performances of Bayesian probabilistic inference with respect to state-of-the-art methodologies using, e.g., parametric fits based on periodic functions, by both reducing false detections and increasing true positives. Our approach also exploits ancillary data derived from a digital elevation model, including slopes, normalized heights above nearest drainage (HAND), and SAR imaging parameters such as shadow and layover conditions. It is here tested over an area that includes the so-called Metaponto Coastal Plain (MCP), in the Basilicata region (southern Italy), which is recurrently subject to floods. We illustrate the ability of our system to detect known (although not ground-truthed) and smaller, undocumented inundation events over large areas, and propose some consideration about its prospective use for contexts affected by similar events, over various land cover scenarios and climatic settings.
Research performed in the framework of project GEORES-Applicativo GEOspaziale a supporto del miglioramento della sostenibilità ambientale e RESilienza ai cambiamenti climatici nelle aree urbane”, funded by the Italian Space Agency (ASI), Agreement n. 2023-42-HH.0. R.C. thanks Francesco Zucca (Department of Earth and Environmental Sciences, University of Pavia, 27100 Pavia, Italy) and Monica Bini (Department of Earth Sciences, University of Pisa, 56126 Pisa, Italy) for their invaluable help.
[Sim.PSI2024] V. Simeone, A. Doglioni, G. D’Ambrosio, A. Fiorentino, D. O. Nitti, R. Nutricato, A. Guerricchio, "Nutcracker Deformation Of Arch Bridge In Consequence Of Slow Gravitational Slope Deformations", Procedia Structural Integrity, Volume 62, 2024, Pages 561-568. DOI:10.1016/j.prostr.2024.09.079. ISSN:2452-3216. Proceedings of II Fabre Conference – Existing bridges, viaducts and tunnels: research, innovation and applications (FABRE24). URL: https://www.sciencedirect.com/science/article/pii/S2452321624006644.
Italy is a geologically young territory and still subject to tectonic actions and orogenic thrusts, originating a significant and continuous geomorphological evolution. This is expressed both by landslides and by phenomena of slow deformation of the slopes. These are sometimes seemingly imperceptible deformations, which however can potentially lead to long-term damage to infrastructure, as for the case of the famous Lagonegro bridge. Very small deformations that modern technologies allow us to objectively document and monitor by satellite images. These images, when appropriately analyzed and elaborated, contribute to the understanding of the dynamics of territory. This work presents a set of cases related to arch bridges deformed by slow but continuous thrusts linked to gravitational phenomena which give rise to compressive deformations of the abutments which can give rise to deformations of the bridges which can be defined as "nutcracker". In this work, a roundup of Italian examples of how slow gravitational slope deformations can lead to the collapse of bridges is reported. It is also presented a preliminary investigation on bridge deformation based on satellite techniques. It is briefly presented the case of Albiano-Magra bridge in Tuscany, which collapsed in April 2020, and the case of the Lagonegro bridge which was dismissed since 1952. Other cases presented are the former FFSS 12-arch bridge of the old Paola Cosenza railway line, cases of masonry arch bridges in Basilicata along provincial roads 154 and 103 in the province of Matera and the case of the former FAL bridge of Cassano to the Ionian Sea in the province of Cosenza. These are all examples of how slow deformations can affect arch bridges creating the condition for the failure or for the final compromission of the bridge.
This publication has been prepared using European Union's Copernicus Land Monitoring Service information. This work is part of the project: “Analysis of the impacts on slow landslides based on remote sensing techniques”, granted by Apulian Regional Government, RIPARTI, project number 39786e0f. The authors wish to thank FABRE– “Research consortium for the evaluation and monitoring of bridges, viaducts and other structures” (www.consorziofabre.it/en), for the opportunity of presenting this case study, any opinion expressed in the paper does not necessarily reflect the view of the funder.
International Conference Proceedings
[Sai.IAC2024] E. Sain, V. Fortunato, C. A. De Donno, L. Amoruso, L. Agrimano, C. Abbattista, D. Drimaco, R. Nutricato, A. Parisi, T. di Noia, G. Fasano, F. Giordano, A. Bigazzi, "Tower-Check: designing a real-time monitoring architecture for high voltage overhead power lines using SAR on-board processing techniques". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24,B1,8,9,x83213
The escalating frequency of extreme weather events observed over the past few decades, driven by climate change, poses a critical threat to the structural integrity of strategic ground infrastructure, including high voltage overhead power lines. Power outages, caused by a structural failure of the transmission tower or even a loss of the transmission cable, may have a significant economic impact on business and households located within the disrupted area. Monitoring high voltage power lines and locating the damage within a few hours after the extreme weather event becomes especially crucial in mountainous regions, where conventional inspection methods such as aerial surveys using airplanes, Unmanned Aerial Vehicles (UAVs) or ground-based personnel, may prove expensive and potentially hazardous. The privileged viewpoint of a Synthetic Aperture Radar (SAR) satellite platform answers the need to image visibly damaged power lines even during nighttime and severe weather conditions. However, since data coming from SAR satellites is currently handled within the ground segment, information is not promptly available to the managing authority of the power lines infrastructure, to deploy a maintenance team in a timely manner. To bridge the gap, Planetek Italia S.r.l. together with its commercial partners Geophysical Application Processing S.r.l., Politecnico di Bari and Università degli Studi di Bari, is pioneering an innovative monitoring solution for SAR platforms leveraging Artificial Intelligence and Machine Learning (AI/ML) techniques implemented in the space segment for on-board processing. The proposed design is targeted to identify precisely located damages on transmission towers by means of on-board SAR high resolution data processing supported by AI/ML algorithms. Specifically, the objective of the AI/ML techniques is to autonomously detect anomalies in power line infrastructure accurately characterized by geometry and exact position, thus delivering an almost instantaneous alert to the final user. A synergy of different approaches is proposed that aim to optimize the computational effort of the final on-board computer and the resources needed for downlink operations, thus providing a solution expressly tailored for on-board low power consumption platforms. This research is supported by the Italian Space Agency (ASI; Agenzia Spaziale Italiana) in the framework of the REASEARCH DAY “GIORNATE DELLA RICERCA ACCADEMICA SPAZIALE” initiative, through contract no. ASI-PKI-2023-5-E.0.
This research is supported by the Italian Space Agency (ASI; Agenzia Spaziale Italiana) in the framework of the RESEARCH DAY “GIORNATE DELLA RICERCA ACCADEMICA SPAZIALE” initiative, through contract no. ASI-PKI-2023-5-E.0.
[Mor.IAC2024] A. Morea, D. O. Nitti, R. Nutricato, A. Parisi, K. Tijani, C. Abbattista, L. Agrimano, L. Amoruso, R. Milella, D. Chirulli, F. Bovenga, "Fully Automated Extraction of accurate Ground Control Points from Sentinel-1/2 acquisitions". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24,B1,4,x87417
This work outlines the key components of a completely automated system designed to create Ground Control Points (GCP) using Earth Observation (EO) data. The system relies on SAR and optical images obtained from the Copernicus Sentinel-1/2 constellation, which are widely accessible worldwide. The system was created by Planetek Italia and GAP companies as part of the ESA SEN3GCP project ("Sentinel for 3D Ground Control Point"). SEN3GCP is designed to offer Ground Control Points (GCPs) and accurate co-registration of Earth Observation (EO) products through an automated service that can be accessed via M2M Rest API and a dedicated portal on the Rheticus® platform. The article describes the algorithm developed for generating Ground Control Points (GCPs), which include a reference point with precise geographical coordinates (including height information) and an optical image chip focused on the target. Bright targets (e.g., SAR-Harris corners) are initially robustly detected on multiple radargrammetric datasets in Same-Side or Opposite-Side Looking configurations, which are despeckled by temporal filtering to preserve the native spatial resolution. A matching procedure identifies key-points that correspond to the same target on various SAR datasets, enabling 3D spatial triangulation and geographical location calculation. The GCP geolocation accuracy is improved by addressing air signal propagation delays, geodynamic phenomena such as solid earth tides, and timing corrections related to the bistatic residual errors. The SAR image chip, created by combining geocoded Multi-Image Reflectivity maps, is compared with super-resolved optical data using advanced techniques such as Mutual-Information and Histogram of Oriented Phase Congruency. The algorithm's robustness was improved by using data collected over a calibration test site at the Physics Department of Bari, which provides a cluster of artificial reflectors, including both passive (trihedral corners) and active (transponders). The prototype service has been thoroughly and successfully evaluated using EO data obtained from the Sentinel constellation, while the performance evaluation with X-band high-resolution SAR data is currently under progress. The performance assessment was conducted on more than 20,000 Ground Control Points (GCPs) gathered from various test sites in Italy, encompassing both flat and hilly terrains. The evaluation utilized ground-truth data obtained via GNSS field surveys, high-resolution orthophotos, and LIDAR Digital Elevation Models. This work also presents the key results of the performance evaluation, focusing on the spatial density of GCPs and the accuracy of 3D geolocation, according to the target category such as vertical poles, light towers, buildings, metal structures.
The present study has been carried out in the framework of the SEN3GCP project ("Sentinel for 3D Ground Control Point"), co-funded by the European Space Agency (ESA) through the EO science for society Permanently Open Call for Proposals EOEP-5 BLOCK 4 mechanism (ESA Contract No. 4000129984/20/I-DT).
[Nit.IAC2024] D. O. Nitti, S. Atzori, C. Bignami, G. Ceriola, C. La Mantia, V. Massimi, A. Morea, R. Nutricato, A. Parisi, E. Royer, K. Tijani, C. Tolomei, "Multi-temporal SAR Interferometry Service for the Monitoring of Seismic Wide Areas". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24-B1,8,8,x87497
One of the pivotal aspects of the Italian government's National Recovery and Resilience Plan (PNRR) concerns the allocation of resources to space activities for Earth Observation, leading to the establishment of the IRIDE program. IRIDE adopts a comprehensive approach to Earth Observation, featuring an End-to-End System comprising distinct segments: Upstream, Downstream, and Services. At the core of IRIDE program lies the Service Value Chain (SVC) concept, facilitating the provision of geospatial-based services at national and European levels. In this paper, we describe the architecture and initial findings of a specific SVC aimed at monitoring active seismic areas during different seismic phases. Leveraging advanced analysis techniques, the proposed SVC aims at providing detailed monitoring during co-seismic, post-seismic, and inter-seismic periods, shedding light on regional geodynamic processes. The monitoring approach relies on the analysis of Persistent Scatterer (PS) and Distributed Scatterer (DS) displacement time series derived from the multi-temporal interferometric analysis of SAR data calibrated with data from regional GNSS networks. By employing spatial clustering and fitting temporal displacement models, the proposed SVC distinguishes between exponential decay indicative of post-seismic activity and linear trends associated with inter-seismic phases, also identifying temporal anomalies in PS/DS time series for selected strategic assets characterized by velocity changes or cumulative displacement steps exceeding predefined thresholds. The investigated areas of interest concern Italian seismic regions characterized by significant crustal strain and classified by the INGV DISS working group, such as the Norcia seismic area for co- and post-seismic phases analysis, and the Mattinata seismic fault for inter-seismic phase investigation. Through this SVC, we show how stakeholders gain valuable insights into ground motion dynamics, contributing to improved seismic phenomena characterization.
The IRIDE constellation is a programme of the European Union – NextGenerationEU – PNRR Italia Domani. Funded by the European Union – NextGenerationEU. Funded by the Presidency of the Council of Ministries pursuant to Article 1, paragraph 254, of Law 160/2019. Funded by the Presidency of the Council of Ministries from the Complementary Fund. IT PNRR CUP J58G21000010007 (Unique Project Code identifying procurements actions in the frame of Italian PNRR - M1C2.4.2 Earth Observations interventions regarding ESA)
[Nit.IAC2024a] D. O. Nitti, R. Nutricato, A. Parisi, K. Tijani, F. Bovenga, "Investigating amplitude and InSAR phase from passive and active artificial reflectors". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24-B1,4,x87488
The present contribution aims at assessing reliability, precision and limitations of using artificial reflectors (ARs) for supporting the ground displacement monitoring based on spaceborne Interferometric Synthetic Aperture Radar (InSAR) data. ARs are usually deployed in order to: i) calibrate SAR spaceborne sensors; ii) increase the spatial density of displacement measurements in areas lacking coherent targets such as rural, forested, and mountainous areas; iii) target and monitor the stability of specific parts of buildings and infrastructures. Urban context poses some additional challenges such as the interaction with surrounding structures, which may corrupt both amplitude and phase signals. An experimental site has been set up by deploying two passive corner reflectors (CRs) and three active reflectors over a building roof. Each CR consists of three triangular metal panels welded perpendicularly to each other to form a trihedral shape whose internal edge is respectively 69.5 cm (CR0) and 1.05 m (CR1). Concerning the active reflectors, one is the Electronic Corner Reflector at C-band (ECR-C) produced by MetaSensing, which is compatible with operating frequencies of Sentinel-1 and RADARSAT-2. The other two were designed in the early ‘90s for supporting the calibration of SAR sensors operating at C-band (ARC-C) and X-band (ARC-X). ECR-C and ARC-C have been tuned to work with the Sentinel-1 C-band SAR mission, while ARC-X has been exploited for working with COSMO-SkyMED X-band constellation. ECR-C works with both ascending and descending orbits, through software switching, while ARC-C and ARC-X have to be re-oriented mechanically to be pointed towards either ascending or descending passes. CR0 and ARC-X are oriented to be visible from ascending passes and the former can be lifted upward to simulate millimetric displacements along the sensor line of sight. CR1 and the ARC-C are pointed towards descending passes. The deployment site and the AR’s locations have been selected with the specific aim of evaluating the impact of signals coming from surrounding structures, which is a relevant issue when using ARs for monitoring the stability of specific parts of a building. The proposed experimental set up allows comparing results obtained by using both CRs and active reflectors, as well as results obtained by using CRs of different sizes, which means different SNR conditions for both amplitude and phase signals. Moreover, we investigated the interaction between Sentinel-1 signals coming from CR-1 and ARC-C positioned at different mutual distances and working at different polarizations.
The experimental activities related to the present work have been conducted with reference to the ESA project “Quantum Computing for ground motion measurement” ESA/RFQ/3-17708/22/I-DT-lr.
[Gua.IAC2024] C. Guaragnella, R. Nutricato, D. O. Nitti, A. Morea, A. Parisi, "Towards Real-Time Blind focusing of SAR data". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24-B1,4,x87465
In the last decades, SAR data processing related to radar satellite missions has led to the development of many applications related to several fields of Earth observation, such as land and infrastructure monitoring. Satellite SAR configuration is often monostatic, that is with transmitter and receiver in the same space platform, and it can also be bistatic, where the main challenge is related to the synchronization between transmitter and receiver. Regardless of the type of SAR configuration, the geometric set-up of SAR acquisition system, as well as ancillary data acquired in correspondence of transmitter and receiver locations are necessary in order to apply standard model-based algorithms of SAR data-focusing. Aiming to maximize opportunistic SAR applications, this article presents the potential applications of a blind technique to SAR data-focusing based on the use of the Singular Values Decomposition (SVD) and LMS fitting of the phase information extracted from singular vectors. The presented blind SAR-data focusing algorithm is able to obtain a focused-SAR image based on a complex SAR raw data matrix without any additional geometric or radiometric information. To reduce the computational time of SAR data focusing, algorithm works partitioning in blocks the raw image and, after focusing, merging the focalized blocks. To show the potential of this blind technique, such as the utilization of opportunistic radar receivers, the development of cost-effective SAR systems related to aerial unmanned vehicles, and potentialities of real-time on-board SAR data focusing, preliminary results related to raw SAR data will be presented and discussed, highlighting strengths and weaknesses of such applications. In particular, emphasis will be placed on raw SAR data acquired by the Italian Earth-imaging constellation COSMO Sky-Med with reference to the “stripmap” sensor imaging operating mode, which is among the most common mode to obtain SAR image.
This research is supported by the Italian Space Agency (ASI, Agenzia Spaziale Italiana) within the framework of the ASI Tower Check project, in the framework of the RESEARCH DAY “GIORNATE DELLA RICERCA ACCADEMICA SPAZIALE” initiative, through contract no. ASI-PKI-2023-5-E.0.
[Tag.IAC2024] N. Taggio, M. Sylos Labini, G. Benekos, D. Drimaco, A. Morea, K. Tijani, "Automated Coastal Zone Classification using AI: A systematic method to perform comprehensive land use and land cover classification in coastal areas". Proceedings of the International Astronautical Congress (IAC) 2024, Milan, Italy, October 14-18, 2024. ID: IAC-24-B1.128.x83899
Land cover and land use classification (LU/LC) through remote sensing data poses significant challenges due to factors such as spectral variability, mixed pixels, seasonal changes, and the complexity of urban and natural environments. Coastal regions in Europe, which are rich in biodiversity, face threats from human activities, necessitating detailed and reliable information for sustainable management. In 2020, Planetek Italia led an industrial consortium to develop the first Copernicus Land – very high resolution (VHR) Coastal Zone hotspot thematic mapping product for European coastal zones. This initiative provides specific LULC information to address environmental challenges, covering approximately 730,000 km² with a minimum mapping unit of 0.5 ha across 71 LC/LU classes. However, much human effort has been spent to perform the classification. This work employs advanced machine learning (ML) and deep learning (DL) techniques, including standard DL classifier such as U-Net and an innovative foundation model called Prithvi, to improve classification efficiency and reduce the effort of human photo-interpreters. The results demonstrate that both U-Net and Prithvi achieved comparable overall accuracy in classifying 26 different classes across two different nations (~70%), showcasing the effectiveness of these models in coastal zone mapping.
[Ref.IGARSS2024] A. Refice, G. Caporusso, F.P. Lovergine, R. Nutricato, D.O. Nitti, A. Parisi, R. Colacicco, D. Capolongo, M. Virelli, D. Tapete, A. Ursi, "On the Integration of Intensity, Interferometric Coherence and Polarization Diversity in Flood Detection from Long Stacks of Multi-Frequency SAR Data Through a Bayesian Framework", International Geoscience and Remote Sensing Symposium (IGARSS), Pages 1506-1509, 2024 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2024, Athens 7-12 July 2024, Code 202443, ISBN: 979-835036032-5, DOI: 10.1109/IGARSS53475.2024.10641731, Scopus: 2-s2.0-85204883096.
Bayesian estimation of posterior probabilities for the presence of floodwaters, coupled with accurate time series regression methods, show good performance in the monitoring of inundations at high temporal and spatial resolution from long stacks of synthetic aperture radar (SAR) data. We report results on the integration of SAR intensity and cascaded InSAR coherence time series in different polarization channels within a Bayesian framework. The method is being tested over sites in both northern and southern Italy, with X- and C-band SAR data. The results indicate some advantage in using more than one independent channel in the Bayesian inference for some types of land cover, in terms of area under the curve (AUC) when compared to independent flood maps acquired over known events. Stacks of surface water confidence levels computed over both test sites show promising characteristics, both on agricultural and coastal areas.
Research performed in the framework of the projects “GEORES - Applicativo GEOspaziale a supporto del miglio-ramento della sostenibilità ambientale e RESilienza ai cam-biamenti climatici nelle aree urbane”, funded by the Italian Space Agency (ASI), Agreement n. 2023-42-HH.0, and the RiPARTI project “Monitoring of extreme hydrometeorologi-cal events from high-resolution remotely sensed data (Mon-itoraggio di eventi estremi idrometeorologici da dati telerile-vati ad alta risoluzione)”, funded by Regione Puglia, Italy.
[Laf.IGARSS2024] R. Lafortezza, F. Giordano, D. Capolongo, A. Refice, F. P. Lovergine, M. Elia, N. Amoroso, R. Nutricato, D. O. Nitti, A. Parisi, A. Ursi, P. Sacco, M. Virelli, D. Tapete, "The GEORES project: geospatial application in support of environmental sustainability and resilience to climate changes in urban areas", International Geoscience and Remote Sensing Symposium (IGARSS), Pages 1593-1596, 2024 IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2024, Athens 7-12 July 2024, ISBN: 979-835036032-5, DOI: 10.1109/IGARSS53475.2024.10642728
The GEORES project is funded by the Italian Space Agency (ASI) and aims to develop a geospatial application meant to improve environmental sustainability and resilience to climate changes in urban areas, based on the synergistic use of the most advanced Earth Observation (EO) technologies, Artificial Intelligence (AI) and eXplainable AI (XAI). GEORES is organized into four main modules to support management of the main risks associated with land degradation: (1) Sediment Connectivity; (2) Land Displacement; (3) Urban Floods; (4) Urban Wildfires. For each module, EO data, calculation models and algorithms are integrated to identify “hot-spots” of urban and peri-urban territory at high risk from the point of view of land degradation caused by phenomena of hydrogeological instability, sediment flow or vegetation fires. The extracted information is expressed with specific indicators (“geo-analytics”) calculated dynamically and automatically. The demonstration is undertaken in the Metropolitan City of Bari and Gargano Promontory, Apulia Region, southern Italy, and foresees the engagement of final users (i.e. Regional Civil Protection and Municipality of Bari).
The R&D activities presented in this paper are developed within the GEORES project, funded by the Italian Space Agency (Agreement n. 2023-42-HH.0) as part of ASI’s program “Innovation for Downstream Preparation for Science” (I4DP_SCIENCE).
[Pet.SPIE2024] P. Petio, V. Massimi, D. Iasillo, T. Fazio, G. Forenza, N. Taggio, S. Samarelli, D. O. Nitti, R. Nutricato, M. Cardone, M. E. Cianfanelli, "Development of an operational infrastructure monitoring service for predictive maintenance based on Rheticus Safeway", Proceedings of SPIE Remote Sensing 2024, Paper 13197-38, 16–19 September 2024, Edinburgh, United Kingdom.
"Ground motion phenomena can cause serious damage to infrastructures and the environment, and it represents a risk for the citizens. Landslides may destroy roads, and railways, even causing victims. In recent years, the continuous growth of the intensity and frequency of extreme natural phenomena has been observed, and there is a clear relationship between both human activities and climate change.
Planetek Italia, with GAP, is developing an operational infrastructure monitoring service to support predictive maintenance of roads, railways, and bridges. The initiative, supported by the Italian Space Agency (ASI) under the I4DP Market project, targets providing a comprehensive solution aligned with the guidelines for risk classification, safety assessment, and monitoring of existing bridges, as outlined by the Italian Ministry of Infrastructure and Transport.
The proposed operational service builds upon the existing Rheticus® Safeway, developed by Planetek within the Horizon 2020 Safeway project concluded in February 2022. The enhancements and adaptations, performed during the ASI project encompass operational and technological aspects, to democratise and scale the service to a European and global level.
The service will be based on ground motion data derived from multitemporal satellite interferometry algorithms, primarily leveraging SAR Sentinel-1 (S-1) and COSMO-SkyMed (CSK) data, alongside change detection from multispectral satellite Sentinel-2 (S-2) data.
To ensure the service's generalizability, scalability, and availability across various levels of detail, the European Ground Motion Service (EMGS) of Copernicus is proposed as a baseline service for ground motion monitoring accessible throughout the European Union. An additional service tier with higher temporal and spatial resolution is foreseen to provide updates on-demand, based on SAR COSMO-SkyMed and Sentinel-1 data processing to derive the ground motion map and the Sentinel-2 to identify the land cover changes.
The adoption of this operational infrastructure monitoring service will mark a significant step towards efficient and proactive maintenance strategies, leveraging satellite-based geo-analytics information to ensure the safety and resilience of roads and railways infrastructure networks on a broader scale."
Activity carried out under the project Rheticus® Safeway (ASI n. 2023-28-I.0)
Conference Abstracts
[Cap.ENEA2024] G.Caporusso, A. Refice, F.P. Lovergine, R. Nutricato, D.O. Nitti, R. Colacicco, D.Capolongo, D. Tapete, A. Ursi, DEVELOPMENTS AND APPLICATION OF A BAYESIAN STATISTICAL APPROACH TO MAP FLOOD EVENTS FROM SAR DATA TIME SERIES, Extended Abstracts of the 14° Workshop tematico di Telerilevamento ENEA, 6-7 Giugno 2024, Bologna, Italy. URL: https://www.eventi.enea.it/images/presentazioni2024/2024_06_06_telerilevamento/Telerilevamento-AIT-2024.pdf
Recent methods of mapping floods benefit from remote sensing. A statistical analysis of historical time series of remotely sensed data can be used to determine the likelihood associated with the presence of water in an area of interest. Lidar, optical, GNSS, and Synthetic Aperture Radar (SAR) data can be used to this end. SAR data, which can be collected independently from illumination and cloud cover conditions, are particularly useful to monitor floods with high resolution in both space and time. Probabilistic algorithmic techniques, like the Bayesian model, are appropriate for the analysis of time series of the variables under consideration. In the hypothesis of wanting to define the concept of flood risk in a given area, the proposed method defines the flood confidence level connected to the presence/absence of water on the surface which can be assessed through the intensity and interferometric coherence quantities associated with the SAR images, in different polarizations when available, according to a Bayesian approach [1]. In this context, floods are considered as temporally impulsive events lasting a single, or a few consecutive acquisitions within a series of hundreds of SAR images. Specifically, ongoing research work concerns the design of a method capable of estimating the historical series of flooding confidence maps, over an area of interest. Hydrogeomorphological ancillary data, including maps of slope, height above the nearest drainage (HAND) and radar layover/shadow, are useful aids for characterizing the probability calculations within the Bayesian model. According to Bayes’ equation [2], we can express the posterior probability for the presence of floodwater (F) for a certain pixel at a certain time t, conditioned by the observables, as a function of the flood likelihoods, the non-flood likelihoods and the a priori probabilities. The observable variables that can be examined include the intensity, k (normalized backscatter), and the interferometric coherence, s intended here as the coherent correlation between consecutive SAR images. These can be used in different polarization combinations such as vertical-or horizontal-transmit / receive (VV, VH, etc.), and combined in the Bayes' Theorem. The flood likelihoods can be estimated from Gaussian distributions of data fitted over permanent water areas, whereas, to estimate the likelihood of no-flood conditions, we consider the residuals of the time series with respect to a temporal model trend, assumed to be a smooth function, relying on the above-mentioned assumption that flood events appear as anomalies in a temporal SAR intensity or coherence trend. Generally, the smooth variables variations in time over land areas can be modelled as parametric functions, such as low-degree polynomials or sums of harmonic terms. In our work we use Gaussian processes (GP)-based regression to fit the temporal intensity and coherence time series. The prediction is probabilistic (Gaussian), so that one can compute empirical confidence intervals (online fitting, adaptive fitting) for the prediction in some region of interest. Different autocovariance functions, or kernels, can be specified. Common kernels are provided, but it is also possible to specify custom kernels. GPs are valid alternatives to parametric models, in which data trends are modeled by "learning" their stochastic behavior by optimizing some "hyperparameters" of a given kernel [3]. We present results over three case studies. The first one concerns the Metaponto coastal plain, in the Basilicata Region (southern Italy), facing the Ionian Sea. The area is crossed by five main rivers, i.e. Bradano, Basento, Cavone, Agri and Sinni, which reach the Gulf of Taranto with directions perpendicular to the coastline. In the last two decades the area has been affected by a recurrence of flood events from these rivers, which have caused extensive economic damage to infrastructures, agricultural, geotourism activities and archaeological heritage, although with an intensity that is not exceptional on an absolute scale. In this case, attention was paid to the flood events of 11-18 March 2016, 27-28 March 2018, 18-23 October 2018 and 26-27 March 2020. For the study of this area images from the Sentinel-1 C-band satellite constellation were used, in VV and VH polarizations, acquired from an ascending orbit from 2015 to 2021, and made openly available by the European Space Agency (ESA) [4]. The second case study concerns an inland area of Northern Italy located in the Piedmont region, crossed by the Sesia river and its tributaries, which involves various municipalities, including Vercelli, and in which there are several rice fields. In October 2020, after incessant rains that hit upper Piedmont, the floods of the Sesia devastated the valley floor causing the collapse of the bridge connecting the municipalities of Gattinara and Romagnano Sesia. In this context, a flood event that occurred on 4-6 October 2020 was examined. To study this area, another Sentinel-1 C-band time series in VV and VH polarizations in ascending orbit from 2015 to 2023 was used. The third study area concerns the Gargano promontory, north of the Puglia region, in the eastern part of the Foggia province, semi-surrounded by the Adriatic Sea. Here the surface hydrographic network is deeply incised into the Gargano mountains. Exceptions are small areas in the north, where a few seasonal waterways of limited length and flow are concentrated, which flow into the Adriatic in the municipal areas of Vico del Gargano and Rodi Garganico, or which flow into the coastal lakes of Lesina and Varano. In this area, attention was paid to flood events occurred on 15-16 July 2016, 18-19 July 2021 and 28 August 2021. For the study of this area, a series of COSMO-SkyMed images in X-band was used, acquired in HH polarization, in ascending orbit from 2011 to 2022. These data were made available by the Italian Space Agency (ASI) in the framework of the GEORES collaborative project (Geospatial application to support the improvement of environmental sustainability and resilience to climate change in urban areas - Agreement n.2023-42-HH.0) between the University of Bari (UNIBA), the Institute for Electromagnetic Sensing of the Environment of the Italian National Research Council (CNR-IREA), and ASI. With regard to the first case study, the time series of confidence maps of the presence of surface water was obtained, and validated through comparison with rainfall data acquired from three rain gauge stations located in areas where flooding was detected on the dates indicated. By observing the condition of some pixels within the study area, a more effective classification capacity was found through confidence maps of the presence of water created through Gaussian Processes fits compared to those created through harmonic fits. A problematic aspect of some particularly intense atmospheric disturbances was highlighted, which may alter the C-band SAR signal in the Sentinel-1 images, causing classification errors in terms of confidence in the presence of surface water. In the second case study, the time series of the confidence maps of the presence of surface water were obtained through different combinations of the variables within the extended formula of Bayes' Theorem. A validation of each type of output map was attempted through the computation of ROC curves based on the comparison with the Copernicus Emergency Management Service (ECMS) map referring to the flood event of 4 October 2020 (activation ECMS EMSR468; https://emergency.copernicus.eu/mapping/listof-components/EMSR468). Subsequently, a study was conducted for each type of land cover, according to the Corine Land Cover 2021 map distributed by the Higher Institute for Environmental Protection and Research (ISPRA). Within this area of study, evaluations are underway regarding the possibility of defining more specific kernel functions capable of making Gaussian Process regression more effective, and whose hyperparameters can be used also for classification purposes. In the third case study, the time series of the confidence maps of the presence of surface water were obtained by applying Bayes' Theorem with respect to the variables ??& and ??&. In this case, the sequence of water confidence maps highlights a significant involvement of the coastal strip and some small internal areas of the Gargano promontory. Also in this case, classification errors were detected due to atmospheric disturbances that altered the X-band SAR signal in the COSMO-SkyMed images. This last research work has recently found application within the GEORES project. GEORES is based on the synergistic use of the most advanced Earth Observation technologies and methods based on artificial intelligence (AI, XAI) for the identification of portions of urban and peri-urban territory at high risk from the point of view of land degradation caused by hydrogeological instability phenomena, sediment flow and/or vegetation fires [5]. The project involves the integration of data, calculation models and algorithms developed by the University of Bari (Agronomy, Physics and Geology Departments) in collaboration with CNR-IREA and, jointly with ASI, the component related to flood risk will be developed using the confidence maps of the presence of water deduced from the Bayesian statistical approach.
This research is carried out within the GEORES project, funded by the Italian Space Agency (Agreement n. 2023-42-HH.0) under the ASI’s program “Innovation for Downstream Preparation for Science” (I4DP_SCIENCE).
[Arg.SGI2024] I. Argentiero, F. Bovenga, R. Borrelli, V. Massimi, R. Nutricato and D.O. Nitti, "Analysis tools for supporting the exploitation of MTInSAR products in monitoring landscape evolution", in Abstract Book of the SGI-SIMP joint congress "Geology for a sustainable management of our Planet", pag. 438, Bari, Italy, 2-5 September 2024. DOI:10.3301/ABSGI.2024.02.
Multi-temporal SAR interferometry (MTInSAR), by providing both mean displacement maps and displacement time series over coherent objects on the Earth’s surface, allows analyzing wide areas, identifying ground displacements, and studying the phenomenon evolution at a long-time scale. The analysis of MTInSARbased displacement time series can provide useful information for long-term monitoring, management, and risk assessment at the regional level, when combined with planning tools, and support decision-makers at a local level in risk management. This analysis can be complicated due to the amount of data and, for this reason, it is essential to identify tools to accelerate the investigation of MTInSAR products. This work presents the results obtained by using analysis tools of MTInSAR data in Rheticus® Safeland, developed by Planetek Italia, which provides prevention and mitigation services of land instability hazards. We tested two tools (density and distribution tool) aimed at assessing the reliability of the information provided by MTInSAR products and two automated procedures (Fuzzy Entropy indicator, FE, Nonlinear Trend Analysis, NLTA), recently developed (Bovenga et al., 2022; Bovenga et al., 2021; Refice et al., 2022), for the identification of a smaller set of coherent targets (CTs) showing nonlinear displacement trends related to instability phenomena. The density tool concerns the percentage of surface of the study area covered by CTs. The tool combines the satellite geometry defined according to parameters coming from the MTInSAR processing (i.e. LOS direction and orbital state vectors), and the ground geometry obtained by exploiting geomorphic information (i.e. the average slope, the prevailing exposure, and the surface area). The distribution tool evaluates the spatial distribution of CTs: the velocity values derived from a dense spatial distribution of CTs covering uniformly the whole study area are more reliable than those derived from a few sparse targets. The FE index is able to recognize displacement time series characterized by strong non linearities and jumps related to phase unwrapping errors, which should be corrected before further analysis. The NLTA, based on the Fisher statistics, allows classifying targets according to the degree of a polynomial function, which optimally describe the displacement trend. Density and distribution tools were successfully exploited for assessing the reliability of the data provided by MTInSAR products, and, based on this, for identifying areas where the actual displacement is properly represented by MTInSAR data. FE and NLTA were very effective in supporting the analysis of ground displacements provided by MTInSAR, since they allow focusing on a smaller set of CTs corresponding to unstable areas or structures on the ground. Consequently, the integration of these tools within Rheticus® Safeland increases the level of information for users, who may respond more effectively to their needs.
[Ias.CLMS2024] D. Iasillo, V. Massimi, T. Fazio, G. Forenza, N. Taggio, R. Nutricato, D. O. Nitti, M. Cardone, E. M. Cianfanelli, "Rheticus® Safeway: an EGMS-based operational infrastructure Monitoring Service for Predictive Maintenance", Poster Presentation at the 1st General Assembly of the Copernicus Land Monitoring Service (CLMS), Antwerp, Belgium, 3-5 June 2024.
"The project Rheticus® Safeway, promoted by the Italian Space Agency (ASI) in the frame of the I4DP Market, aims to develop an operational infrastructure monitoring service to support predictive maintenance of roads, railways, and bridges aligned with the guidelines for risk classification, safety assessment, and monitoring of existing bridges. The proposed operational service builds upon the existing Rheticus® Safeway, developed by Planetek within the Horizon 2020 Safeway project concluded in February 2022. The enhancements and adaptations, performed during the ASI project encompass both operational and technological aspects, to democratize and scale the service to a European and global level.
In particular, to ensure the service's generalizability, scalability, and availability over the European Union, the European Ground Motion Service (EMGS) of Copernicus is proposed as a baseline service for ground motion monitoring accessible throughout the European Union.
Additionally, a secondary level of service for continuous updates is established, harnessing SAR COSMO-SkyMed and Sentinel-1 data.
The project team is led by Planetek Italia, together with G.A.P. s.r.l."
Activity carried out under the project Rheticus® Safeway (ASI n. 2023-28-I.0)
[Tag.URBIS2024] N. Taggio, V. Massimi, R. Nutricato, D. O. Nitti, M. Simone, "Enhancing Infrastructure Resilience: Leveraging Machine Learning for Urban Land Use Change Monitoring", Oral presentation at URBan Insights from Space (URBIS) 2024, ESA-ESRIN, 16-18 September 2024.
The study of land cover and land use (LCLU) changes in urban areas is crucial for understanding city dynamics. Activities such as deforestation, mining, and agriculture can significantly impact the landscape and soil, potentially leading to erosion or instability. These threats increase the risk of landslides or soil subsidence, which can damage infrastructure such as roads and railways. Remote sensing data, particularly from multispectral and multitemporal optical imagery, plays a key role in monitoring these changes. Automated approaches using artificial intelligence and machine learning have been effective in identifying LCLU classes, aiding in global change studies. Planetek Italia is developing an infrastructure monitoring service aimed at predictive maintenance of roads, railways, and bridges. This service uses supervised machine learning to analyse LCLU changes with time-series Sentinel-2 data. Supported by the Italian Space Agency under the I4DP Market project, the initiative aligns with guidelines from the Italian Ministry of Infrastructure and Transport for risk classification and safety assessment of bridges. It builds on the Rheticus® Safeway service, developed under the Horizon 2020 Safeway project, and aims to scale the service for broader European and global use. This monitoring service represents a significant advancement in proactive maintenance strategies, leveraging satellite-based geo-analytics to enhance the safety and resilience of infrastructure networks.
[Mas.URBIS2024] V. Massimi, G. Ceriola, N. Taggio, R. Nutricato, D. O. Nitti, D. Drimaco, "Capacity Building activities for Asian Development Bank to promote the use of the EO services in developing Countries", Oral presentation at URBan Insights from Space (URBIS) 2024, ESA-ESRIN, 16-18 September 2024.
The Asian Development Bank (ADB) operates through resident missions in various regions, and their development missions require access to Earth Observation (EO) products and tools to enhance the understanding of climate change impacts, natural hazards, and disasters that affect the areas they are overseeing. The EO-developed products offer valuable support to policy and decision-makers in several ways: 1. Providing Essential Baseline Information for implementing projects in developing countries by the IFI like ADB: the developed satellite EO-based geohazards and geo-analytics represent an innovative solution that provides new ways for ADB to address challenges in developing countries. 2. Support the geo-hazards risks assessment at the country scale: The worldwide coverage and high-revising time guaranteed by the Copernicus satellites present an unprecedented opportunity for natural hazard assessment and its continuous monitoring at the country scale. 3. Empower decision-makers: The operational use of the developed satellite EO-derived products at the country scale is expected to empower the decision-makers with accurate information for: Resilient strategies implementation; To support sustainable development and disaster risk reduction; Recovery support after a natural disaster. 4. Better understanding the benefit of operational use of the EO-derived products: The EO-developed products increased the benefit awareness connected with the operational use of Earth Observation products in development projects. To promote the operational application of the developed EO products in operational projects, the ADB supported dedicated capacity-building activities involving the national authorities of Indonesia, Papua New Guinea, and Bangladesh in different projects where Planetek Italia was involved starting from 2018 through the ESA project EO4SD.
[Amo.RS2023] N. Amoroso, R. Cilli, D. O. Nitti, R. Nutricato, M. C. Iban, T. Maggipinto, S. Tangaro, A. Monaco, and R. Bellotti. 2023. "PSI Spatially Constrained Clustering: The Sibari and Metaponto Coastal Plains", Remote Sensing 15, no. 10: 2560. EISSN 2072-4292. DOI:10.3390/rs15102560, Scopus:2-s2.0-85160623377, WOS:000996794300001, IF(2023): 4.2, IF(5-Year): 4.9 (Source: MPDI).
PSI data are extremely useful for monitoring on-ground displacements. In many cases, clustering algorithms are adopted to highlight the presence of homogeneous patterns; however, clustering algorithms can fail to consider spatial constraints and be poorly specific in revealing patterns at lower scales or possible anomalies. Hence, we proposed a novel framework which combines a spatially-constrained clustering algorithm (SKATER) with a hypothesis testing procedure which evaluates and establishes the presence of significant local spatial correlations, namely the LISA method. The designed workflow ensures the retrieval of homogeneous clusters and a reliable anomaly detection; to validate this workflow, we collected Sentinel-1 time series from the Sibari and Metaponto coastal plains in Italy, ranging from 2015 to 2021. This particular study area is interesting due to the presence of important industrial and agricultural settlements. The proposed workflow effectively outlines the presence of both subsidence and uplifting that deserve to be focused and continuous monitoring, both for environmental and infrastructural purposes.
Authors would like to thank IT resources made available by ReCaS, a project funded by the MIUR (Italian Ministry for Education, University and Research) in the “PON Ricerca e Competitività 2007–2013-Azione I-Interventi di rafforzamento strutturale” PONa3_00052, Avviso 254/Ric, University of Bari. This paper has been supported by the TEBAKA (TErritorial BAsic Knowledge Acquisition project “Avviso MIUR n. 1735 del 13/07/2017”.
[Son.JAG2023] A. Sonnessa, A. di Lernia, D. O. Nitti, R. Nutricato, E. Tarantino and F. Cotecchia, "Integration of Multi-sensor MTInSAR and ground-based geomatic data for the analysis of non-linear displacements affecting the urban area of Chieuti, Italy". International Journal of Applied Earth Observation and Geoinformation, Volume 117, 2023, 103194, ISSN 1569-8432, 2023. DOI:10.1016/j.jag.2023.103194, Scopus:2-s2.0-85146587258, WOS:000926876700001, IF: 7.6 (Source: 2023 Journal Citation Reports)
Slow instability phenomena can turn into rapid events, showing sudden accelerations and potentially developing in a threat for structures and people. In such scenarios, an in-depth understanding of the spatial and temporal evolution of the ground surface displacement field becomes essential for preventing potential catastrophes. In this work, Multi-Temporal Interferometry SAR (MTInSAR) technique, based on COSMO-SkyMed and Sentinel-1 SAR acquisitions, and ground measurements, have been used to study an ongoing instability occurrence, affecting the urban area of Chieuti, a town located in the Southern Italy. Archives of C and X-band SAR and geomatic monitoring data spanning seven, five and one year, respectively, have been analyzed exploiting the complementary characteristics of these datasets. This enabled the accurate spatial-temporal characterization of the ground displacement field in the study area, the identification of sectors evidencing instability problems and the reliability assessment of the detected displacements trends, characterized by strong non-linearities. Moreover, the multi-geometry DInSAR analysis allowed to evaluate the horizontal and vertical components of the detected motion, confirming the nature of the instability process, related to a deep landslide mechanism affecting the western slope of the town.
This research has been conducted under the agreement between the DICATECh and Government Commissioner for the environmental risk of Apulia. Authors are very grateful to Apogeo s.r.l. and AGLab at Politecnico di Bari for their support in the levelling measurements and Planetek Italia s.r.l. for making available the MTInSAR dataset. All authors have read and agreed to the published version of the manuscript.
[Net.AutConstr2023] A. Nettis, V. Massimi, R. Nutricato, D. O. Nitti, S. Samarelli, G. Uva, "Satellite-based interferometry for monitoring structural deformations of bridge portfolios". Automation in Construction, Volume 147, March 2023, 104707. DOI: 10.1016/j.autcon.2022.104707. Print ISSN: 0926-5805. Online ISSN: 1872-7891. Scopus:2-s2.0-85146698507. WOS:000923332500001. IF(2023):10.517 (Source: ScienceDirect).
The multi-temporal satellite-based differential interferometry (MTInSAR) is a well-known remote-sensing tech-nique aimed at detecting displacements of persistent scatterers (PSs) on the terrestrial surface. Recent studies motivate research effort on developing efficient and automatic procedures for structural monitoring via MTIn-SAR. This paper proposes a methodology for the portfolio-scale detection of structural deformations of bridges via MTInSAR. The displacement time-series associated with persistent scatterers on the investigated bridges are used to supply a geoprocessing chain leading to the automatic interpretation of bridge-specific deformation scenarios and the definition of monitoring/assessment priority classes. The methodology is applied to two highway networks in Roma and Bari (Italy) by using Sentinel-1 (C-band) and COSMO-SkyMed (X-band) satellite datasets. Although most of the bridges can be assumed stable, a relevant number of bridges affected by ongoing deformation phenomena are associated with high inspection priority. The PSs and the deformation scenarios related to some specific test bridges subjected to subsidence phenomena are analysed and described in detail. Finally, the deformation scenarios detected through the proposed methodology for two collapsed bridges in Italy are illustrated.
[Cas.TECH2023] G. Cascelli, C. Guaragnella, R. Nutricato, K. Tijani, A. Morea, N. Ricciardi and D. O. Nitti. 2023. "Use of a Residual Neural Network to Demonstrate Feasibility of Ship Detection Based on Synthetic Aperture Radar Raw Data" Technologies 11, no. 6: 178. ISSN: 2227-7080, DOI:10.3390/technologies11060178, Scopus:2-s2.0-85180673891, WOS:001132333800001, IF(2023): 4.2 (Source: MPDI)
Synthetic Aperture Radar (SAR) is a well-established 2D imaging technique employed as a consolidated practice in several oil spill monitoring services. In this scenario, onboard detection undoubtedly represents an interesting solution to reduce the latency of these services, also enabling transmission to the ground segment of alert signals with a notable reduction in the required downlink bandwidth. However, the reduced computational capabilities available onboard require alternative approaches with respect to the standard processing flows. In this work, we propose a feasibility study of oil spill detection applied directly to raw data, which is a solution not sufficiently addressed in the literature that has the advantage of not requiring the execution of the focusing step. The study is concentrated only on the accuracy of detection, while computational cost analysis is not within the scope of this work. More specifically, we propose a complete framework based on the use of a Residual Neural Network (ResNet), including a simple and automatic simulation method for generating the training data set. The final tests with ERS real data demonstrate the feasibility of the proposed approach showing that the trained ResNet correctly detects ships with a Signal-to-Clutter Ratio (SCR) > 10.3 dB.
This work was supported by the Advanced Payload Data Processing for Autonomy & Decision (APP4AD) project: contract with the Italian Space Agency (n. 2021-6-E.0), Codice Unico di Progetto (CUP) (F95F21000020005).
[DAm.IJEGE2023] G. D’Ambrosio, A. Doglioni, D. O. Nitti, "The impact of very slow moving gravitative slope deformations on infrastructures: the case study of the Bridge of Ginosa", Italian Journal of Engineering Geology and Environment (IJEGE), Special Issue 1 (2023): 33-38, E-ISSN:2035-5688, ISSN:1825-6635, DOI: 10.4408/IJEGE.2023-01.S-05, Scopus:2-s2.0-85164606630, WOS:001041534100006, IF(2023-2024):0.8 (Source: Citefactor).
Slow and very slow-moving landslides are quite common in Italy and in zone of recent tectonic uplift, in particular in clayey or sandy-clayey slopes. These landslides are not easy to be detected, since their extremely slow movements do not apparently produce effects. However, whereas structures or infrastructures exist and are stressed by slow landslides, their impacts can damage the structures/infrastructures. Bridges are valuable infrastructures, potentially threatened by slow moving landslides. Bridges can warp if stressed, but their resilience is limited. Therefore, the progressive and constant increasing of the stress due to slow landslides can cause failures of the bridges, and potentially collapses. In Italy, a large part of the bridges was built or rebuilt just after the WWII. These infrastructures are now aged and whereas slow moving landslides exist, they are suffering potentially dangerous stresses. This work focuses on a peculiar case study of a little bridge built between 1940 and 1947, located in south Italy, stressed and damaged by a slow-moving landslide.
This work is carried out within the project: “Analysis of the impacts on slow landslides based on remote sensing techniques”, granted by Apulian Regional Government, RIPARTI, project number 39786e0f. Rheticus® is a registered trademark of Planetek Italia srl. The authors are sincerely grate to prof. Vincenzo Simeone, for his critical review of the paper and for the constructive discussion on this subject.
International Conference Proceedings
[Nit.SPIE2023] D. O. Nitti, R. Nutricato, K. Tijani, F. Bovenga, A. Refice, R. Bellotti, G. Preziosa, and A. Mongelli, "Exploiting artificial reflectors for SAR interferometry applications", Proc. SPIE 12732, Microwave Remote Sensing: Data Processing and Applications II, 1273204 (17 October 2023), ISSN:0277-786X, eISSN:1996-756X, ISBN:978-151066693-1, DOI:10.1117/12.2680622, Scopus:2-s2.0-85177849043, WOS:001118792300003.
This work is devoted to assessing reliability, precision and limitations of using artificial reflectors (AR) for supporting the displacement measurements derived through Spaceborne Multi-temporal SAR interferometry (MTInSAR). An experimental site has been set up by deploying two trihedral corner reflectors (CR) whose side length is respectively 0.7 m (CR-1) and 1 m (CR-2), and one compact active transponder (CAT) used to support the calibration for both ERS and ENVISAT missions. All AR have been tuned to work with the Seintinel-1 mission. In details, CR-1 is oriented to be visible from ascending passes, while CR-2 and the CAT are oriented to be visible from descending passes, and can be moved to simulate millimetric displacements. Both ascending and descending Sentinel-1 stacks have been processed through the SPINUA processing chain, then time series of both SAR amplitude and displacement values have been analysed for assessing the accuracy of MTInSAR measurements, and evaluating the potential improvements provided by using AR. Moreover, tThe proposed experimental set up allows comparting i) results obtained by using CR and CAT; and ii) results obtained by using CR of different sizes, which means different SNR conditions for both amplitude and phase signals. Furthermore, the reflectors have been deployed over a building roof in order to evaluate the impact of signals coming from other structures surrounding the AR. This is a relevant issue when using AR for monitoring the stability of specific parts of a building. This instrumented test site will be proposed as an open experimental site by providing open -data for testing and validating interferometric techniques.
This work was supported by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, PON R&I, 2014–2020 under project “Close to Earth” (ID ARS01_00141). Authors thank Saverio Triggiani for supporting the field activities.
[Par.SPIE2023] A. Parisi, D. O. Nitti, R. Nutricato, G. Preziosa, A. M. Loconsole, F. Prudenzano, C. Guaragnella, "Investigating radar cross sections of passive radar reflectors for C-band and X-band SAR satellite missions", Proc. SPIE 12732, Microwave Remote Sensing: Data Processing and Applications II, 1273203 (17 October 2023), DOI: 10.1117/12.2679842, ISSN:0277-786X, eISSN:1996-756X, ISBN:978-151066693-1, Scopus:2-s2.0-85177841011, WOS:001118792300002.
The lack of stable and coherent natural targets can threat the effectiveness of Interferometric Synthetic Aperture Radar (InSAR) applications. To overcome this issue, active and passive radar reflectors are designed. Thanks to their low cost of construction and maintenance, passive radar reflectors are even more employed as coherent targets to assess potential displacement measurements of land, buildings, and infrastructures. In the present study, different types of passive radar reflectors are investigated by simulating their backscattering characteristics through a 3D electromagnetic software and by calculating their radar cross sections at different azimuth and incidence angles. Simulation results have been examined by considering the characteristics of current SAR satellite missions orbiting on different planes (Sun-Synchronous Orbit/MidInclination Orbit) and considering both passes (Ascending/Descending), as well as by analyzing different orientations of SAR antenna (i.e., Right/Left look sides and incidence angles). Advantages and disadvantages of the investigated passive radar reflectors are highlighted in terms of their visibility on multiple Line Of Sights (LOS). Two carrier frequencies have been selected, that are close to those of operational SAR satellites: 5.405 GHz (C-band) and 9.66 GHz (X-band).
This work has been carried out in the in the framework of the Project “Monitoraggio di spostamenti con transponder RADAR” granted by Regional Government of Puglia Region, RIPARTI project number 2a171b1e, POC PUGLIA FESRTFSE 2014/2020.
[Amo.IAC2023] L. Amoruso, L. Agrimano, C. Abbattista, C. De Donno, V. Fortunato, M. Depalma, D. Chirulli, C. Brighenti, M. Barison, G. Farinati, F. Brighenti, T. Khalid, A. Morea, N. Ricciardi, R. Nutricato, D. Nitti,"APP4AD, the Advanced Payload data Processing for Autonomy & Decision agent for future EO and planetary exploration missions", Proceedings of the 74th International Astronautical Congress (IAC), Baku, Azerbaijan, 2-6 October 2023. ID: IAC-23,B4,9-GTS.5,8,x76688. ISSN:00741795, Scopus:2-s2.0-85187975115.
With the goal of evolving the current "concepts of operations" of space systems such as Earth Observation and planetary exploration, it is necessary to increase, including by means of artificial intelligence techniques, the system's autonomous and timely reaction capabilities to external events and unplanned situations, and responding to the need for reduced control by the Earth ground station. Therefore, an on-board software component (for satellites or planetary rovers) has been designed and developed that implements and makes available known (and classified) object and event recognition and "novelty" capabilities, acting in fully automatic mode and in (near) real-time. There are two reference scenarios. The first concerns the EO domain and aims at the identification of events with rapid evolution and transient phenomena, which justify new acquisitions (with different modes and resolutions or with different sensors), but which may become extinct if data processing requires operator intervention or otherwise has significant time, e.g., oil spills detection with Synthetic Aperture Radar data. The second scenario, which includes rovers for planetary science (Moon/Mars), responds to the trade-off between the minimum level of detail of observations required to avoid "losing" objects of scientific interest, the resources required for data transmission and processing, and the time devoted (which reduces the number of possible searches). In both cases, a system that enables fully automatic recognition of anomalies and novel elements in the acquired data is also capable of implementing behavior that is sensitive to the information content of the acquired data. The ability, therefore, to assess already on board, in real-time, the information content of the data and to decide accordingly, adapting behaviors to the situation, establishes an extremely novel element with respect to current operational scenarios. Furthermore, the lack of the expected information in the data (under unsuitable acquisition conditions or due to the absence of events of interest) also introduces new possibilities for optimizing on-board resources (mass memory, communication bandwidth, power). Accompanying this algorithmic design is implemented a SW infrastructure capable of being deployed on all currently used/under development computing architectures, aiming at the definition of a flexible HW/SW ecosystem responsive to the ever-increasing capabilities of embedded computing systems for Space environment. This activity is being performed by a consortium of three Italian SMEs, of which Planetek Italia is the prime along with, Geophysical Applications Processing and S.A.T.E. Systems & Advanced Technologies Engineering, on behalf of the Italian Space Agency (ASI).
This work is funded by the Italian Space Agency as part of the call for industrial research projects called TRANSVERSAL ENABLING TECHNOLOGIES to promote the development of innovative ideas in the field of onboard space technologies. ASI CONTRACT reference number is n. 2021-6-E.0.
Conference Abstracts
[Cas.Geodaysit2023] G. Cascelli, C. Guaragnella, A. Morea, K. Tijani, N. Ricciardi, R. Nutricato, "Bright Target Detection on SAR Raw Data Based on Deep Convolutional Neural Networks", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/URR3NB/
Since the deployment of the first satellite equipped with a Synthetic Aperture Radar (SAR) into orbit in 1978, the use of SAR imagery has been a vital part of several scientific domains, including environmental monitoring, early warning systems, and public safety. SAR could be described as "non-literal imaging" since the raw data does not resemble an optical image and is incomprehensible to humans. For this reason, raw data is typically processed to create a Single Look Complex (SLC) image, which is a high-resolution image of the scene being observed. The processing of raw data to create a SLC image involves several steps, including range compression, Doppler centroid estimation and azimuth compression. Processing raw data requires a significant amount of computer power; as a result, it is almost never practical to do it on board. As a direct consequence, the data is transmitted back to Earth to be processed. The objective of next-generation studies [1] is to optimize Earth Observation (EO) data processing and image creation in order to deliver EO products to the end user with very low latency using a combination of advancements in the on-board parts of the data chain. In this work, we focus on a sea scenario and propose to eliminate any pre-processing by training a Deep Convolutional Neural Network (DCNN) to directly recognize bright targets on raw data. This indeed might substantially shorten the delivery time thus improving the efficiency of satellite-based maritime monitoring services. In this regard, the availability of training data represents one of the critical issues for the development of machine learning algorithms. In fact, the efficacy of the final machine learning-powered solution for a specific application is ultimately determined by the quality and amount of the training data. However, to date, there are no training SAR raw data available in scientific literature with regard to the specific topic of sea scenario monitoring. Furthermore, their generation from real data is a time-consuming task. In this work we propose and investigate physically and statistically based approaches to simulate a marine scenario and generate realistic synthetic training SAR raw datasets. We then trained and evaluated a state-of-the-art DCNN on the generated synthetic dataset and successively on real raw data extracted from ERS imagery archive. It is one of the first experiments proposed in the SAR literature and results are quite encouraging, as they reveal that a well-trained DCNN can correctly recognize strong scattering objects on SAR raw data. [1] M. Kerr, et al. “EO-ALERT: a novel architecture for the next generation of earth observation satellites supporting rapid civil alerts”, in 71st International Astronautical Congress (IAC), 2020.
This work was carried out in the framework of the APP4AD project (“Advanced Payload data Processing for Autonomy & Decision”, Bando ASI “Tecnologie Abilitanti Trasversali”, Codice Unico di Progetto F95F21000020005), funded by the Italian Space Agency (ASI). ERS data are provided by the European Space Agency (ESA).
[Par.Geodaysit2023] A. Parisi, D. Oscar Nitti, C. Guaragnella, R. Nutricato, G. Preziosa, A. M. Loconsole, F. Prudenzano, "Simulating and comparing Radar Cross Sections of passive radar reflectors for Interferometric Synthetic Aperture Radar applications", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Poster Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/review/ZR8EVZDQF79APXQLSETUCT8LARSBFDAJ
In the field of Interferometric Synthetic Aperture Radar (InSAR), the lack of stable and coherent natural targets can threat the effectiveness of InSAR applications. To overcome this issue, active and passive radar reflectors, which enhance the radar signals backscattering toward radar platforms, are designed. Among the others, passive radar reflectors are very diffused electromagnetic structures due to their low-cost of construction and maintenance. The present study aims at investigating passive radar reflectors focusing on the simulation of their Radar Cross Sections (RCS), which is the measure of a target's capacity to reflect radar signals in the direction of the radar receiver. RCS are simulated by the software CST Studio Suite® varying the microwave incident angle for each considered passive radar reflectors. Results are validated by comparing the RCS peak values simulated by the software CST Studio Suite® with those evaluated by formulas of canonical passive radar reflectors. As the most diffuse operational SAR satellite missions are in C-band (e.g., Copernicus Sentinel-1 and CSA RADARSAT constellations), X-band (e.g., ASI COSMO-SkyMed/COSMO-SkyMed Second Generation missions, and DLR TerraSAR-X/TanDEM-X constellation), and L-band (e.g., JAXA ALOS-2 and CONAE SAOCOM missions), RCS simulations related to plane electromagnetic microwave take into consideration them as reference frequencies. Advantages and disadvantages of passive radar reflectors are highlighted and discussed in terms of the main characteristics of current SAR satellite missions, as well as their visibility on different passes (Ascending/Descending), look sides (Right/Left) and orbital planes (Sun-Synchronous Orbit or Mid-Inclination Orbit).
This work is carried out in the framework of the project: “Monitoraggio di spostamenti con transponder RADAR”, granted by Regional Government of Puglia Region, RIPARTI project number 2a171b1e.
[Nit.Geodaysit2023] D. O. Nitti, A. Morea, K. Tijani, N. Ricciardi, F. Bovenga, R. Nutricato, "Exploitation of Multi-Temporal InSAR data for Environmental Risk Assessment Services", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/EHR9BQ/
Study carried out in the framework of the SeVaRA project, funded by Apulia Region (PO FESR 2014/2020).
[Nit.Geodaysit2023a] D. O. Nitti, F. Bovenga, R. Nutricato, A. Refice, I. Argentiero, G. Pasquariello, G. Spilotro, "Analysis of DInSAR Displacement time series for monitoring slope instability", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/3JY9P3/
Multi-temporal SAR interferometry (MTInSAR), by providing both mean displacement maps and displacement time series over coherent objects on the Earth’s surface, allows analysing wide areas, identifying ground displacements, and studying the phenomenon evolution on long time scales. This technique has also been proven to be very useful for detecting and monitoring instabilities affecting both terrain slopes and man-made objects. In this contest, an automatic and reliable characterization of MTInSAR displacements trends is of particular relevance as pivotal for the detection of warning signals related to pre-failure of natural and artificial structures. Warning signals are typically characterised by high rates and non-linear kinematics. The Sentinel-1 (S1) C-band mission from the European Space Agency (ESA) as well as the high-resolution X-band COSMO-SkyMed (CSK) constellations from Italian Space Agency, both shorten the revisit times up to a few days, thus being very promising for detecting non-linear displacement trends related to warning signals. However, a detailed analysis of MTInSAR displacement products looking for specific trends, is often hindered by the large number of coherent targets (up to millions) to be inspected by expert users to recognize different signal components and also possible artifacts, such as, for instance, those related to phase unwrapping errors. This work concerns the development of methods able to fully exploit the content of MTInSAR products, by automatically identifying relevant changes in displacement time series and to classify the targets on the ground according to their kinematic regime. We introduced a new statistical test based on the Fisher distribution with the aim of evaluating the reliability of a parametric displacement model fit with a determined statistical confidence. We also proposed a new set of rules based on the statistical characterization of displacement time series, which allows different polynomial approximations for MTInSAR time series to be ranked. The method was applied to model warning signals. Moreover, in order to measure the degree of regularity of a given time series, an innovative index was introduced based on the fuzzy entropy, which basically evaluates the gain in information by comparing signal segments of different lengths. This fuzzy entropy index, without postulating any a priori model, allows highlighting time series which show interesting trends, including strong non linearities, jumps related to phase unwrapping errors, and the so-called partially coherent scatterers. These procedures were used for analysing MTInSAR products derived by processing both S1 and CSK datasets acquired over Southern Italian Apennine (Basilicata region), in an area where several landslides occurred in the recent past. Both approaches were very effective in supporting the analysis of ground displacements provided by MTInSAR, since they helped focusing on a smaller set of coherent targets identifying areas or structures on the ground which deserved further detailed geotechnical investigations. Moreover, the joint exploitation of MTInSAR datasets acquired at different wavelengths, resolutions, and revisit times provided valuable insights, with CSK more effective over man-made structures, and S1 over outcrops. Specifically, the work presents an example of slope pre-failure monitoring on Pomarico landslide, an example of slope post-failure monitoring on Montescaglioso landslide, and few examples of structures (such as buildings and roads) affected by instability related to different causes. Our analysis performed on CSK MTInSAR products over Pomarico was able to capture the building deformations preceding the landslide and the collapse. This allows the understanding of the phenomenon evolution, highlighting a change in velocities that occurred two years before the collapse. This variation probably influenced the dynamics of the landslide leading to the collapse of an area considered to be at a medium-risk level by the regional landslide risk map. Results from the analysis performed on S1 MTInSAR products were instead useful to identify post-failure signals within the Montescaglioso landslide body. The selected trends confirm the stability of the landslide area with some local displacements due to restoration works. In this case, the value of the MTInSAR displacement time series analysis emerges in the assessment phase of post-landslide stability, resulting in a useful support tool in the planning of safety measures in landslide areas.
This work was supported in part by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, Programma Operativo Nazionale Ricerca e Innovazione (PON R&I) 2014–2020 under Project OT4CLIMA; and in part by ASI under the Project “CRIOSAR: Applicazioni SAR multifrequenza alla criosfera”, grant agreement N. 2021-12-U.0.
[Nit.Geodaysit2023b] D. O. Nitti, G. D'Ambrosio, R. Nutricato, A. Doglioni, "Study of interaction of slow landslide with infrastructures based on remote sensing technique", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/BEVLYR/
Slow and very slow landslides are quite common in territory which is involved in orogenetic processes like Italian territory. These movements are not immediately evident, since displacements are often a few millimetres per year, and they could be unknown. Landslides are a common natural hazard that can cause significant damage to infrastructure, including bridges, tunnels, railways and buildings. In particular, slow landslides may have a long-term impact on bridges as they often occur over extended periods, and the resulting deformation can be difficult to detect. Remote sensing technologies have emerged as an effective tool for detecting slow landslides and monitoring their impact on bridges. This work provides a comprehensive review of the interaction between slow and very slow landslides and bridges and their analysis using remote sensing techniques. First, the causes and types of landslides are discussed, with a focus on slow landslides and their impact on bridges. The several factors that contribute to slow landslides, including geology and geomorphology, are also presented. Hence we introduce remote sensing technologies that have been used to detect ground displacement and monitor slow landslides, including satellite imagery and multi-temporal synthetic aperture radar interferometry. The use of remote sensing for analysing the impact of slow landslides on bridges is also examined. Finally, the challenges and limitations of using remote sensing for analysing the interaction between slow landslides and bridges are discussed, including their spatial and temporal resolution, and the need for (i) ground truth data for calibration and validation and (ii) for interdisciplinary collaboration between engineers, geologists, and remote sensing experts. The main findings of this study are presented, by highlighting the potential for remote sensing technologies to improve our understanding of the interaction between slow landslides and bridges.
This work is part of the project: “Analysis of the impacts on slow landslides based on remote sensing techniques”, granted by Apulian Regional Government, RIPARTI, project number 39786e0f.
[Nit.Geodaysit2023c] D. O. Nitti, A. Morea, K. Tijani, N. Ricciardi, R. Nutricato, "Real-Time Oil Spill Detection by Using SAR-Based Machine Learning Techniques", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/W3NYLQ/
This study presents a novel approach to monitor oil spills and ships using Synthetic Aperture Radar (SAR) raw data and deep learning techniques. The proposed methodology involves several steps including pre-processing (focusing, filtering and land sea mask), semantic segmentation, and classification using a deep convolutional neural network (DCNN) model, as well as real-time (FFT-based) processing to ensure a fast response. To train the DCNN model, the study combined three datasets: CleanSeaNet, TenGeoP-SARwv, and GAP_OilSpill_DB. The first two datasets are publicly available, while the third dataset was specifically built by the authors by integrating known and documented case studies from news articles and cases identified in the sea area in front of the port of Brindisi (Southern Italy), internally validated by expert GAP operators. Data augmentation techniques were also utilized to improve the model's performance by generating additional training data. The DCNN model uses DeepLab v3+ based on ResNet-18 and is trained on a large dataset of SAR images that includes various types of oil spills, look-alikes, novelty objects, and ships. The proposed system is optimized to process data on board the satellite to ensure a real-time response. The system transmits images to the ground segment only if there is an event of interest (e.g. a novelty object or an oil spill detected eventually involving the nearest ships). The study demonstrates that the proposed approach provides a promising solution for real-time monitoring of oil spills, ships and novelty objects using satellite SAR raw data. The use of deep learning and data augmentation techniques can significantly improve the accuracy and speed of detection, which can ultimately lead to better environmental management and oil spill response. Additionally, the proposed approach can be applied to a variety of SAR datasets and has the potential to be integrated with existing oil spill response systems.
This work was carried out in the framework of the APP4AD project (“Advanced Payload data Processing for Autonomy & Decision”, Bando ASI “Tecnologie Abilitanti Trasversali”, Codice Unico di Progetto F95F21000020005), funded by the Italian Space Agency (ASI). ERS, ENVISAT and Sentinel-1 data are provided by the European Space Agency (ESA).
[Cap.Geodaysit2023] G. Caporusso, D. O. Nitti, F. Bovenga, R. Nutricato, A. Refice, D. Capolongo, R. Colacicco, F. P. Lovergine, A. D’Addabbo, "Probabilistic approach to the mapping of flooded areas through the analysis of historical time series of SAR intensity and coherence.", Geodaysit 2023, Giugno 12-17, 2023, Bari, Italy. Oral Presentation. URL: https://talks.osgeo.org/foss4g-it-2023/talk/WKL8U7/
As part of the analysis of flood events, ongoing studies aim to identify methods of using optical and SAR data in order to be able to map in an ever more precise way the flooded areas that are defined following a flood. At the same time, institutions responsible for territorial security have concrete needs of both monitoring tools capable of describing the susceptibility to flooding and of forecast tools for events with a fixed return time, consistent with the hazard and risk approaches defined, for example, at European or National regulatory level. As far as flood hazards are concerned, hydraulic modeling is currently the most widely used reference for responding to forecasting needs, while the concrete value of remote sensing support emerges in the monitoring context, given the possibility of examining historical series of images referring to any portion of the territory. A statistical approach to the analysis of historical series of satellite images can take into consideration the study of the probability connected to the presence/absence of water in the area, through the analysis of specific indices derived from multi- and hyperspectral optical images (NDVI, NDWI, LSWI) and/or intensity, coherence and radar indices derived from SAR images. In particular, for the study of time series of the variables considered, algorithmic approaches of a probabilistic nature are suitable, such as the Bayesian model and the Theory of Extreme Values. The objective of this work is the assessment of a methodology to return the historical series of the probability of flooding, as well as the corresponding maps, relating to a test area. In this context we present some results related to the study of an agricultural area near the city of Vercelli (Northern Italy), characterized by the presence of widespread rice fields and affected by a major flood of the Sesia river in October 2020. Sentinel-1 SAR images were considered, from which the intensity and interferometric coherence variables can be deduced. The hydrogeomorphological support consist of slope, Height Above the Nearest Drainage (HAND), and Land Cover maps. Through the Copernicus Emergency Management, the flood maps relating to the 2020 event were acquired, to validate the results. Regarding the methodology, the probabilistic modeling of the InSAR intensity and coherence time stacks is cast in a Bayesian framework. It is assumed that floods are temporally impulsive events lasting a single, or a few consecutive acquisitions. The Bayesian framework also allows to consider ancillary information such as the above-mentioned hydrogeomorphology and satellite acquisition geometry, which allow to characterize the a priori probabilities in a more realistic way, especially for areas with low probability of flooding. According to this approach it is possible to express the posterior probability p(F|v) for the presence of flood waters (F) given the variable v (intensity or coherence) at a certain pixel and at a certain time t as a function of the a priori and conditioned probabilities, through the Bayes equation: p(F|v) = p(v|F)p(F) / (p(v|F)p(F) + p(v|NF)p(NF)), with p(F) and p(NF) = 1 - p(F) indicating respectively the a priori probability of flood or no flood, while p(v|F) and p(v|NF) are the likelihoods of v, given the two events. The flood likelihood can be estimated on permanent water bodies, while, to estimate the likelihood of areas potentially affected by flood events, the residuals of the historical series are considered with respect to a regular temporal modeling of the variable v. Gaussian processes (GP) are used to fit the time series of the variable v. GPs are valid alternatives to parametric models, in which data trends are modeled by "learning" their stochastic behavior by optimizing some "hyperparameters" of a given autocorrelation function (kernel). The residuals with respect to this model can be used to derive conditional probabilities and then plugged into the Bayes equation. The availability of the flood maps will allow to tackle the forecasting aspect in the next future, taking the time series of satellite images as a reference.
[Bov.EGU2023] Bovenga, F., Argentiero, I., Belmonte, A., Refice, A., Nitti, D., and Nutricato, R.: Exploiting SAR interferometry for assessing rock glacier activity, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-7731, DOI:10.5194/egusphere-egu23-7731, 2023. URL: https://meetingorganizer.copernicus.org/EGU23/EGU23-7731.html
Rock glaciers are characterised by a mix of ice and rock, which is related to the presence of permafrost in mountainous areas. The external temperature is considered one of the most important factors controlling rock glacier flow variation at both inter-annual and seasonal time scales, showing mean velocities ranging from centimetres to meters per year. Hence, the temperature rising due to climate change leads to changes in kinematics of rock glaciers that increase hazards for mountainous settlements and infrastructures. Despite differential SAR interferometry (DInSAR) is a very effective tool for measuring ground stability, its application to rock glacier monitoring poses critical issues relate to signal decorrelation due to changeable snow cover conditions, as well as to displacement kinematics characterised by both linear and non-linear components and high displacement rates leading to measurements corrupted by aliasing. This work investigates the rock glacier stability in Val Senales (Italian Alps) by processing a dataset of 345 Sentinel-1 SAR images acquired between 2015 and 2022. Multi-temporal DInSAR processing has been performed by exploiting both persistent and distributed scatterers through SPINUA algorithm. Ad hoc processing strategies have been adopted in order to overcome both signal decorrelation due to changeable snow cover conditions, and aliasing due to very high displacement rates. The algorithm has been run by selecting spring-summer acquisitions, and forced to search for solutions corresponding to phase changes behind the aliasing limit. The resulting mean velocity map shows several areas affected by ground displacements, that have been further analysed for investigating the rock glacier activity in the area of interest. To this aim, the DInSAR results (both mean velocity and displacement time series) have been ingested into a GIS environment together with other informative layers such as rock glacier classes (according to [1]) optical orthoimages, multi-temporal mean SAR amplitude, DInSAR coherence maps, permafrost index map, and Difference Vegetation Index (NDVI). Then, the rock glacier activity has reclassified by adopting the more recent procedure proposed in [2], which is based on the DInSAR products too. This new classification has been compared to that derived according to [1] showing several differences. An further interesting issue is related to the lacking of DInSAR coherent targes just within the rock glacier borders that could be related to the presence of very high displacement rates. This has been investigated by exploring changes in orthoimages from different years as well as maps of DInSAR phase and coherence. References: [1] Bollmann, L. Rieg, L., M. Spross, R. Sailer, k. Bucher, M. Maukisch, M. Monreal, A. Zischg, V. Mair, K. Lang, and J. Stötter, “Blockgletscherkataster in Südtirol-Erstellung und Analyse,” Permafrost in Südtirol, Innsbrucker Geographische Studien. J. Stötter & R. Sailer Eds., pp. 147–171, 2012. [2] IPA Action Group - Rock glacier inventories and kinematics. Towards standard guidelines for inventorying rock glaciers: practical concepts (version 2.0), pp. 1–10, 2022.
This work was carried out in the framework of the project “CRIOSAR: Applicazioni SAR multifrequenza alla criosfera”, funded by ASI under grant agreement n. ASI N. 2021-12-U.0.
[Bov.WLF2023] F. Bovenga, I. Argentiero, A. Belmonte, A. Refice, D. Nitti, R. Nutricato, "Assessment of alpine rock glacier activity by exploiting SAR interferometric products", Poster Presentation at 6th World Landslide Forum, Florence, Italy, 14-17/11/2023
Purpose: The Alpine setting is characterized by the presence of periglacial environments rapidly changing due to global warming. In this context, landscape evolution is affected by movements of rock glaciers. They are widespread in European Alps and significant for their content of Alpine permafrost. The external temperature is considered one of the most important factors controlling rock glacier flow variation at both inter-annual and seasonal time scales, showing mean velocities ranging from centimeters to meters per year. This study employs Multi-temporal DInSAR technique to assess the deformation evolution of the rock glaciers and to classify their activity based on DInSAR results and geomorphological features. Methods: This work investigates the rock glacier stability in Val Senales (Italian Alps) by processing a dataset of 345 Sentinel-1 SAR images acquired between 2015 and 2022. Multi-temporal DInSAR processing has been performed by exploiting both persistent and distributed scatterers through SPINUA algorithm. Ad hoc processing strategies have been adopted in order to overcome both signal decorrelation due to changeable snow cover conditions, and aliasing due to very high displacement rates. The algorithm has been run by selecting springsummer acquisitions and forced to search for solutions corresponding to phase changes behind the aliasing limit. The DInSAR results (both mean velocity and displacement time series) have been ingested into a GIS environment together with other informative layers such as rock glacier classes (according to [1]) optical orthoimages, multi-temporal mean SAR amplitude, DInSAR coherence maps, permafrost index map, and Difference Vegetation Index (NDVI). Then, the mean velocity has been classified by adopting the more recent classification proposed in [2]. Lastly, the rock glacier activity has been reclassified by overlapping all available informative layers. Results: The resulting mean velocity map shows several areas affected by ground displacements. Many of these areas corresponds to areas within the border of the rock glaciers in the area of interest. A further interesting issue is related to lack of DInSAR coherent targes just within the rock glacier borders that could be related to the presence of very high displacement rates. This has been investigated by exploring changes in orthoimages from different years as well as maps of DInSAR phase and coherence. The new classification has been compared to that derived according to [1] showing several differences. Conclusions: The Multi-temporal DInSAR technique has proved to be useful for the assessment of rock glaciers, although the interpretation of the results must be supported by other informative layers. The comparison of the two classifications shows both the usefulness of the more recent techniques and the evolution of rock glaciers in recent years due to global warming.
[Bov.WLF2023a] F. Bovenga, I. Argentiero, A. Refice, R. Nutricato, D. Nitti, G. Pasquariello, G. Spilotro, "Multi-temporal SAR interferometry technique for studying slope instability phenomena and their evolution", Poster Presentation at 6th World Landslide Forum, Florence, Italy, 14-17/11/2023
Purpose: Multi-temporal SAR interferometry (MTInSAR), by providing both mean displacement maps and displacement time series over coherent objects on the Earth's surface, allows analyzing wide areas, identifying ground displacements, and studying the phenomenon evolution at a long-time scale. In particular, early warning signals derived from MTInSAR displacement products may be very useful for decision-making processes in the risk assessment phase. This study exploits the potential of COSMO-SkyMed (CSK) and Sentinel 1 (S1) satellite missions to investigate ground and structure displacements related to the slope instabilities. Furthermore, it investigates methods for the automatic identification of nonlinear displacement time series that reliably support the analysis of the huge quantity of coherent targets nowadays available from MTInSAR processing chains. Methods: This work presents the results obtained by analyzing displacement time series from both CSK and S1 for investigating the ground stability of hilly villages located in the Southern Italian Apennines. Both ascending and descending orbits were processed by using the SPINUA MTInSAR algorithm. Mean velocity maps and displacement time series were analyzed, looking, in particular, for nonlinear trends that are possibly related to relevant ground instabilities. This analysis was also supported by automated procedures recently developed, one based on the fuzzy entropy (FE) indicator, the other performing nonlinear trend analysis (NLTA) based on the Fisher statistics. The FE index was able to recognize coherent targets affected by phase unwrapping errors, which should be corrected to provide reliable displacement time series to be further analyzed. The NLTA was used for classifying targets according to the optimal degree of a polynomial function describing the displacement trend. This allowed the focus on a smaller set of coherent targets showing nonlinear displacement trends related to the several ground and structure instabilities. Results: The joint exploitation of MTInSAR datasets acquired at different wavelengths, resolutions, and revisit times provided valuable insights, with CSK more effective over man-made structures, and S1 over outcrops. Both automated procedures were very effective in supporting the analysis of ground displacements provided by MTInSAR, since they helped focusing on a smaller set of coherent targets identifying unstable areas or structures on the ground. In particular, the work presents examples concerning [1]: (i) slope pre-failure monitoring; (ii) slope post-failure monitoring; (iii) displacement evolution monitoring of areas and structures affected by instability related to different causes. Conclusions: These results clearly confirm the valuable use of MTInSAR products as a tool that is additional to the established techniques for studying the dynamics of slope instability phenomena and their evolution. The analysis of MTInSAR-based displacement time series, possibly performed through ad hoc automated procedures, can provide useful information for long-term monitoring, management, and risk assessment at the regional level, when combined with planning tools, and support decision-makers at a local level in risk management.
[DiC.WLF2023] D. Di Carne, A. Doria, M. Antonicelli, S. Samarelli, D. Nitti, R. Nutricato, V. Massimi, Rheticus Displacement to support the design, construction, and maintenaince of infrastructures and consolidation works", Proceedings of the 6th World Landslide Forum. Florence Italy, 14-17 November 2023, Abstract book, ISBN 9791221048063.
Purpose: In 2021, the Special Commissioner for mitigating the hydrogeological risk of the Apulia Region has identified 16 engineering companies for the assignment of engineering and architectural technical services for the reduction of hydrogeological risk (Landslide Plan). The projects were related to 16 lots, located mainly in the Daunia area (north of Apulia Region), for interventions financed through the Operational Plan FSC Environment 2014-2020. Methods: To support the planning and construction of the consolidation works, the Special Commissioner has planned an in-depth monitoring of the evolutionary kinematics of the instability. In particular, support for the design activities with updated information related to the historical ground motion movements has been foreseen for each scheduled mitigation intervention. In particular, in addition to the in-situ monitoring systems (existing or planned), the integration of the satellite monitoring through the multi-temporal interferometry technique was requested to monitor the areas objects of the stabilization works. The Multi-Temporal Interferometry provides a synoptic picture of the monitored phenomena of instability that is useful to support the design activities, and the Special Commissioner’s activities. Results: To answer these needs, the Rheticus Displacement satellite monitoring service provided by Planetek Italia was adopted for the monitoring of the areas subject to interventions. This service provided the ground motion measurements over the areas of intervention subject to instability phenomenon through the processing of data acquired both from Sentinel-1 and COSMO-SkyMed radar satellite constellations processed with the interferometric technique based on the SPINUA algorithm. The Rheticus Displacement service provided the ground motion maps and the historical time series of displacement and geo-analytics for each Persistent Scatterers (PS) and Distributed Scatterers (DS) over the time interval 2015 – 2020. The geo-analytics information has been made available to the Special Commissioner's Office technicians and the designers through the Rheticus Displacement cloud platform. In addition to the Rheticus Displacement access, Planetek Italia provided dedicated on-the-job training to the technicians in charge of the design activities focusing on the results produced with the interferometric analysis and on the functionality of the Rheticus geo-portal. The training activities were essential for fully exploiting the results and their integration within the design phase of the intervention works. Conclusions: Currently, the Rheticus Displacement service is adopted by the Special Commissioner of Apulia Region, among the actions, to monitor the impact of the realized mitigation works continuously, guaranteeing optimal maintenance of the territory over the areas of interest.
[DAm.AIGAA2023] G. D’Ambrosio, A. Doglioni, D. O. Nitti, "The impact of very slow moving gravitative slope deformations on infrastructures: the case study of the Bridge of Ginosa", XII Convegno Nazionale Giovani Ricercatori di Geologia Applicata - Urbino, 2023, 22-24 giugno 2023.
Slow and very slow-moving landslides are quite common in Italy and in zone of recent tectonic uplift, in particular in clayey or sandy-clayey slopes. These landslides are not easy to be detected, since their extremely slow movements do not apparently produce effects. However, whereas structures or infrastructures exist and are stressed by slow landslides, their impacts can damage the structures/infrastructures. Bridges are valuable infrastructures, potentially threatened by slow moving landslides. Bridges can warp if stressed, but their resilience is limited. Therefore, the progressive and constant increasing of the stress due to slow landslides can cause failures of the bridges, and potentially collapses. In Italy, a large part of the bridges was built or rebuilt just after the WWII. These infrastructures are now aged and whereas slow moving landslides exist, they are suffering potentially dangerous stresses. This work focuses on a peculiar case study of a little bridge built between 1940 and 1947, located in south Italy, stressed and damaged by a slow-moving landslide.
This work is carried out within the project: “Analysis of the impacts on slow landslides based on remote sensing techniques”, granted by Apulian Regional Government, RIPARTI, project number 39786e0f. Rheticus® is a registered trademark of Planetek Italia srl. The authors are sincerely grate to prof. Vincenzo Simeone, for his critical review of the paper and for the constructive discussion on this subject.
[Ref.SPIE2023] A. Refice, F. Bovenga, F. P. Lovergine, L. Partipilo, D. Capolongo, R. Nutricato, and D. O. Nitti "Detection of badland erosion by exploring time series of interferometric coherence and phase", Oral Presentation at SPIE Remote Sensing 2023, DOI:10.1117/12.3007787
[Bov.Fringe2023] F. Bovenga, A. Refice, I. Argentiero, R. Nutricato, D. O. Nitti, G. Pasquariello, G. Spilotro, "Advanced Analysis Of InSAR Displacement Time Series For Hazard Monitoring", Poster Presentation, 12th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR" - FRINGE 2023, University of Leeds, Leeds, UK, 11-15/09/2023.
Multi-temporal SAR interferometry (MTInSAR), by providing both mean displacement maps and displacement time series over coherent objectson the Earth's surface, allows analysing wide areas, identifying ground displacements, and studying the phenomenon evolution on long timescales. This technique has also been proven to be very useful for detecting and monitoring instabilities affecting both terrain slopes and man-made objects. In this contest, an automatic and reliable characterization of MTInSAR displacements trends is of particular relevance as pivotalfor the detection of warning signals related to pre-failure of natural and artificial structures. Warning signals are typically characterised by highrates and non-linear kinematics, so reliable monitoring and early warning require a detailed analysis of the displacement time series looking forspecific trends. However, this detailed analysis is often hindered by the large number of coherent targets (up to millions) required to beinspected by expert users to recognize different signal components and also possible artifacts affecting the MTInSAR products, such as, forinstance, those related to phase unwrapping errors. This work concerns the development of methods able to fully exploit the content of MTInSAR products, by automatically identifying relevantchanges in displacement time series and to classify the targets on the ground according to their kinematic regime. We introduced a newstatistical test based on the Fisher distribution with the aim of evaluating the reliability of a parametric displacement model fit with a determinedstatistical confidence [1]. We also proposed a new set of rules based on the statistical characterization of displacement time series, whichallows different polynomial approximations for MTInSAR time series to be ranked. The method was applied to model warning signals. Moreover,in order to measure the degree of regularity of a given time series, an innovative index was introduced based on the fuzzy entropy, whichbasically evaluates the gain in information by comparing signal segments of different lengths [2]. This fuzzy entropy index, without postulatingany a priori model, allows highlighting time series which show interesting trends, including strong non linearities, jumps related to phaseunwrapping errors, and the so-called partially coherent scatterers. The work introduces the theoretical formulation of these two selection procedures and show their performances as evaluated by simulating timeseries with different characteristics in terms of kinematic (stepwise linear with different breakpoints and velocities), level of noise, signal lengthand temporal sampling. The proposed procedures were also experimented on real MTInSAR datasets. We show results obtained by processingboth Sentinel-1 and COSMO-SkyMed datasets acquired over Southern Italian Apennine (Basilicata region), in an area where several landslidesoccurred in the recent past [3]. The MTInSAR displacement time series were analysed by using the proposed methods, searching for nonlineartrends that are possibly related to relevant ground instabilities and, in particular, to potential early warning signals for the landslide events. Theindex based on the fuzzy entropy was able to recognize coherent targets affected by phase unwrapping errors, which should be corrected toprovide reliable displacement time series to be further analyzed. The procedure based on the Fisher distribution was used for classifying targetsaccording to the optimal degree of a polynomial function describing the displacement trend. This allowed to select targets showing nonlineardisplacement trends related to the several ground and structure instabilities. Specifically, the work presents an example of slope pre-failure monitoring on Pomarico landslide, an example of slope post-failure monitoring onMontescaglioso landslide, and few examples of structures (such as buildings and roads) affected by instability related to different causes. Ouranalysis performed on COSMO-SkyMed MTInSAR products over Pomarico was able to capture the building deformations preceding thelandslide and the collapse. This allows the understanding of the phenomenon evolution, highlighting a change in velocities that occurred twoyears before the collapse. This variation probably influenced the dynamics of the landslide leading to the collapse of an area considered to beat a medium-risk level by the regional landslide risk map. Results from the analysis performed on Sentinel-1 MTInSAR products were insteaduseful to identify post-failure signals within the Montescaglioso landslide body. The selected trends confirm the stability of the landslide areawith some local displacements due to restoration works. In this case, the value of the MTInSAR displacement time series analysis emerges inthe assessment phase of post-landslide stability, resulting in a useful support tool in the planning of safety measures in landslide areas.
[Bov.Fringe2023a] F. Bovenga, I. Argentiero, A. Belmonte, A. Refice, G. Cuozzo, M. S. Heredia, M. Callegari, C. Notarnicola, D. O. Nitti, R. Nutricato, "Assessing Rock Glacier Activity In Val Senales By Exploiting Multiband SAR Data Through Differential SAR Interferometry And Offset Tracking", Oral Presentation, 12th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR" - FRINGE 2023, University of Leeds, Leeds, UK, 11-15/09/2023. URL: https://fringe2023.esa.int/iframe-agenda/files/presentation-247.pdf
Rock glaciers are widespread in European Alps and significant for their content of Alpine permafrost. Indeed, they are characterised by a mix ofice and rock, which is related to the presence of permafrost in mountainous areas. The landslide-like behavior of rock glacier is a complexmechanism influenced by the interaction of several factors such as topographical predisposition, internal structure, debris granulometry,temperature, hydrology, and stress conditions. The external temperature is considered one of the most important factors controlling rock glacierflow variation at both inter-annual and seasonal time scales, showing mean velocities ranging from centimetres to meters per year. Hence, thetemperature rising due to climate change leads to changes in kinematics of rock glaciers that increase hazards for mountainous settlementsand infrastructures. Despite differential SAR interferometry (DInSAR) is a very effective tool for measuring ground stability, its application to rock glacier monitoringposes several critical issues. First, the steep topography may lead to unfavorable illuminating conditions in terms of either unfeasible detectionover layover and shadow areas, or low sensitivity to the ground displacement. Second, the presence of dense vegetation and changeable snowcover conditions causes DInSAR signal decorrelation. Third, displacement kinematics are characterised by both linear and non-linearcomponents and high displacement rates leading to measurements often corrupted by aliasing. This work investigates the rock glacier stabilityin Val Senales (Italian Alps) by exploiting both the interferometric phase and amplitude of SAR image stack at C-band and X-band. A multi-temporal DInSAR processing of 345 Sentinel-1 SAR images acquired between 2015 and 2022 was performed by exploiting bothpersistent and distributed scatterers through SPINUA algorithm. Ad hoc processing strategies were adopted in order to overcome both signaldecorrelation due to changeable snow cover conditions, and aliasing due to very high displacement rates. The algorithm was run by selectingspring-summer acquisitions, and forced to search for solutions corresponding to phase changes behind the aliasing limit. The resulting meanline of sight (LOS) displacement map show several areas affected by ground displacements, which lay on exactly within the borders of rockglaciers derived from inventory maps. In some cases, a lack of DInSAR coherent targes occurs just within rock glacier borders, being possiblycaused by very high displacement rates not properly measured by the MTInSAR algorithm despite ad hoc processing. These areas were furtherinvestigated by exploring maps of DInSAR phase and coherence generated from consecutive Sentinel-1 acquisitions, as well as changesoccurring in orthoimages from different years. Moreover, in order to overcome the DInSAR limitations related to high deformation rates, offset tracking techniques were experimented, whichexploit SAR amplitude instead of phase. This analysis was focused on the interesting case study of Lazaun rock glacier [1]. It is a tongue-shaped, 660 m long and 200 m wide, active rock glacier located in Senales Valley (Italy) at about 2600 m asl. Interannual and seasonaldisplacement rates up to few mm/day are reported by previous studies, which used different techniques including GNSS, inclinometers, andboth ground based and spaceborne SAR systems. Offset tracking algorithms can be used to measure displacements with a sensitivity that is afraction of the data spatial resolution. For the Lazaun case study, we adopted the intensity tracking algorithm, considering that the alternativealgorithm based on coherence tracking, is unfeasible due to the low coherence values encountered in the test area. Considering thetopography, the size of the area of interest, and the expected entity of the displacement, SAR data acquired along ascending orbits in spotlightmode are those more reliable for displacement estimation through intensity tracking. In particular, we selected six TerraSAR-X staring spotlightand six COSMO-SkyMed Second Generation (CSG), both with a pixel spacing of less than 1m, acquired in the snow free period between 2016and 2018 (TerraSAR-X) and in 2022 (CSG). These datasets were processed by optimizing the parameters according to the characteristics ofLazaun test case. The displacement maps derived along azimuth and range directions allowed to investigate both seasonal and inter-annualmovements occurring on the rock glacier. GPS field campaigns were also carried out in correspondence with some of the satellite acquisitions.A comparison of the results obtained with ground and satellite data were performed showing for the annual displacement a root mean squaredifference of 0.347 and 0.355 mm/day, with a Pearson coefficient of 0.883 and 0.895 in azimuth and range direction respectively. These resultscoming from offset tracking provide useful displacement information within the Lazaun borders, where the MTInSAR approach instead suffer oflack of coherent targets due to phase aliasing. Finally, both mean rates and displacement time series were ingested into a GIS environment together with other informative layers such asmulti-temporal mean SAR amplitude, DInSAR coherence maps, rock glacier classes (according to [2]), optical orthoimages, permafrost indexmap, and Difference Vegetation Index (NDVI). Then, the rock glacier activity was reclassified by adopting the more recent procedure proposedin [3], which is based also on the DInSAR products. This new classification was compared to that derived according to [2] showing severaldifferences. For instance, 3 out of the 6 rock glaciers classified as indefinite were reclassified as relict or translational, 6 out of the 11 rockglaciers classified as relict were reclassified as transitional, and conversely, one rock glacier classified as active was reclassified as relict.
This work was carried out in the framework of the project “CRIOSAR: Applicazioni SAR multifrequenza alla criosfera”, funded by ASI under grant agreement n.ASI N. 2021-12-U.0.
[Ref.FRINGE2023] A. Refice, G. Caporusso, R. Colacicco, D. Capolongo, R. Nutricato, D. O. Nitti, A. D'Addabbo, F. Bovenga, F. P. Lovergine, "Flood Monitoring Through Advanced Modeling of SAR Intensity and InSAR Coherence Temporal Stacks", Poster Presentation, 12th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR" - FRINGE 2023, University of Leeds, Leeds, UK, 11-15/09/2023.
Monitoring of flood events with high resolution in both the spatial and the temporal domain is becoming more and more feasible thanks to the availability of long time series of images acquired by both synthetic aperture radar (SAR) and optical sensors [1]. Many approaches have been proposed; among the most promising, those which cast the problem of flood water detection into a Bayesian probabilistic framework [2, 3] allow to treat in a flexible way a variety of heterogeneous information, and give as output a probability value for the presence of water in each considered image sample, which can be easily interpreted in terms of confidence. SAR temporal image stacks represent an ideal tool to monitor the presence of water over large areas and with high temporal frequency in a systematic way, given the relative insensitivity of microwave signals to the presence of clouds and other atmospheric phenomena, and the active nature of SAR sensors. Recent international initiatives aim at operational provision of this kind of maps globally [4]. We independently developed a procedure which exploits the high-frequency characteristics of sensors such as the European Sentinel-1 (S1) constellation to account for slow backscatter changes on land areas, based on the assumption that floods are temporally impulsive events lasting for a single, or a few consecutive acquisitions [5]. The Bayesian framework also allows to consider ancillary information such as topography and satellite acquisition geometry, which can be cast into prior probability distributions which taper to zero for locations unlikely to be flooded. In this contribution, we expand the treatment to the modeling of InSAR coherence temporal stacks. We limit our analysis to SAR interferograms obtained combining subsequent acquisitions with the shortest temporal baseline, which in the case of the S1 sensor is of 6 days for most of the sensor lifetime (thanks to the availability of the twin sensors S1-A/B from 2016 up to December 2021), or 12 days for the remaining periods. This choice allows for the maximum contrast between flooded and non-flooded areas, as on the latter temporal decorrelation is minimized. As in the analysis of backscatter intensities, we can express the posterior probability p(F|g) for the presence of floodwater (F) given the coherence g at a certain pixel and at a certain time t (assuming coherence between times t and t+1) as a function of prior absolute and conditioned probabilities, through Bayes' equation: p(F|g) = p(g|F)p(F) / (p(g|F)p(F) + p(g|NF)p(NF)), with p(F) and p(NF) = 1 - p(F) indicating the a priori probability of flood or no flood, respectively, while p(g|F) and p(g|NF) are the likelihoods for the coherence values, given the two events. The flood likelihood can be estimated over permanent water areas, whereas, to estimate the likelihood of non-permanent water areas potentially interested by flood events, we consider the residuals of the time series with respect to a temporal model trend, assumed to be a smooth function, relying on the above mentioned assumption that flood events appear as (negative) anomalies in a temporal coherence trend. Proper care must be paid in these modeling efforts to take into account the intrinsic coherence statistics, which generally differs from that of SAR intensity signals [6]. Nevertheless, S1 coherence time series have been recently shown to exhibit smooth, periodic trends over agricultural areas in southern Italy in non-flooded conditions [7]. We use Gaussian processes (GPs) [8] to fit the time series. GPs are viable alternatives to parametric models, in which the trends of the data are modeled by "learning" their stochastic behaviour through optimization of some "hyperparameters" of an assigned autocorrelation function (kernel). Residuals with respect to such model can be used to derive conditioned probabilities and thus inserted into Bayes' equation. We present some results of an analysis exploiting both SAR intensity and coherence S1 time series over an agricultural area near the town of Vercelli (Northern Italy), characterized by the presence of widespread rice paddies, and hit by at least a large flood from the Sesia river in October 2020. The test site appears particularly challenging for the temporal modeling, as rice paddies are periodically inundated for normal agricultural practices, causing variability in both SAR intensity and InSAR coherence.
Work performed in the framework of the RiPARTI project "Monitoring of extreme hydrometeorological events from high-resolution remotely sensed data (Monitoraggio di eventi estremi idrometeorologici da dati telerilevati ad alta risoluzione)", funded by Regione Puglia, Italy. Sentinel-1 data are provided by the European Space Agency.
[Col.FRINGE2023] R. Colacicco, A. Refice, A. Belmonte, F. Bovenga, F. P. Lovergine, R. Nutricato, D. O. Nitti, D. Capolongo, "SAR Interferometry To Detect Badlands Erosion", Poster Presentation, 12th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR" - FRINGE 2023, University of Leeds, Leeds, UK, 11-15/09/2023.
Monitoring of flood events with high resolution in both the spatial and the temporal domain is becoming more and more feasible thanks to the availability of long time series of images acquired by both synthetic aperture radar (SAR) and optical sensors [1]. Many approaches have been proposed; among the most promising, those which cast the problem of flood water detection into a Bayesian probabilistic framework [2, 3] allow to treat in a flexible way a variety of heterogeneous information, and give as output a probability value for the presence of water in each considered image sample, which can be easily interpreted in terms of confidence. SAR temporal image stacks represent an ideal tool to monitor the presence of water over large areas and with high temporal frequency in a systematic way, given the relative insensitivity of microwave signals to the presence of clouds and other atmospheric phenomena, and the active nature of SAR sensors. Recent international initiatives aim at operational provision of this kind of maps globally [4]. We independently developed a procedure which exploits the high-frequency characteristics of sensors such as the European Sentinel-1 (S1) constellation to account for slow backscatter changes on land areas, based on the assumption that floods are temporally impulsive events lasting for a single, or a few consecutive acquisitions [5]. The Bayesian framework also allows to consider ancillary information such as topography and satellite acquisition geometry, which can be cast into prior probability distributions which taper to zero for locations unlikely to be flooded. In this contribution, we expand the treatment to the modeling of InSAR coherence temporal stacks. We limit our analysis to SAR interferograms obtained combining subsequent acquisitions with the shortest temporal baseline, which in the case of the S1 sensor is of 6 days for most of the sensor lifetime (thanks to the availability of the twin sensors S1-A/B from 2016 up to December 2021), or 12 days for the remaining periods. This choice allows for the maximum contrast between flooded and non-flooded areas, as on the latter temporal decorrelation is minimized. As in the analysis of backscatter intensities, we can express the posterior probability p(F|g) for the presence of floodwater (F) given the coherence g at a certain pixel and at a certain time t (assuming coherence between times t and t+1) as a function of prior absolute and conditioned probabilities, through Bayes' equation: p(F|g) = p(g|F)p(F) / (p(g|F)p(F) + p(g|NF)p(NF)), with p(F) and p(NF) = 1 - p(F) indicating the a priori probability of flood or no flood, respectively, while p(g|F) and p(g|NF) are the likelihoods for the coherence values, given the two events. The flood likelihood can be estimated over permanent water areas, whereas, to estimate the likelihood of non-permanent water areas potentially interested by flood events, we consider the residuals of the time series with respect to a temporal model trend, assumed to be a smooth function, relying on the above mentioned assumption that flood events appear as (negative) anomalies in a temporal coherence trend. Proper care must be paid in these modeling efforts to take into account the intrinsic coherence statistics, which generally differs from that of SAR intensity signals [6]. Nevertheless, S1 coherence time series have been recently shown to exhibit smooth, periodic trends over agricultural areas in southern Italy in non-flooded conditions [7]. We use Gaussian processes (GPs) [8] to fit the time series. GPs are viable alternatives to parametric models, in which the trends of the data are modeled by "learning" their stochastic behaviour through optimization of some "hyperparameters" of an assigned autocorrelation function (kernel). Residuals with respect to such model can be used to derive conditioned probabilities and thus inserted into Bayes' equation. We present some results of an analysis exploiting both SAR intensity and coherence S1 time series over an agricultural area near the town of Vercelli (Northern Italy), characterized by the presence of widespread rice paddies, and hit by at least a large flood from the Sesia river in October 2020. The test site appears particularly challenging for the temporal modeling, as rice paddies are periodically inundated for normal agricultural practices, causing variability in both SAR intensity and InSAR coherence.
[Bov.RS2022] F. Bovenga, I. Argentiero, A. Refice, R. Nutricato, D.O. Nitti, G. Pasquariello, G. Spilotro, "Assessing the Potential of Long, Multi-Temporal SAR Interferometry Time Series for Slope Instability Monitoring: Two Case Studies in Southern Italy". Remote Sens. 2022, 14 (7), 1677. DOI:10.3390/rs14071677. Scopus: 2-s2.0-85128037820. WOS:000781257900001. ISSN: 2072-4292. IF(5 years):5.353 (Source: Remote Sensing, 2022).
Multi-temporal SAR interferometry (MTInSAR), by providing both mean displacement maps and displacement time series over coherent objects on the Earth’s surface, allows analyzing wide areas, identifying ground displacements, and studying the phenomenon evolution at a long time scale. This technique has also been proven to be very useful for detecting and monitoring slope instabilities. For this type of hazard, detection of velocity variations over short time intervals should be useful for early warning of damaging events. In this work, we present the results obtained by using both COSMO-SkyMed (CSK) and Sentinel-1 (S1) data for investigating the ground stability of two hilly villages located in the Southern Italian Apennines (Basilicata region), namely the towns of Montescaglioso and Pomarico. In these two municipalities, landslides occurred in the recent past (in Montescaglioso in 2013) and more recently (in Pomarico in 2019), causing damage to houses, commercial buildings, and infrastructures. SAR datasets acquired by CSK and S1 from both ascending and descending orbits were processed using the SPINUA MTInSAR algorithm. Mean velocity maps and displacement time series were analyzed, also by means of innovative ad hoc procedures, looking, in particular, for non-linear trends. Results evidenced the presence of nonlinear displacements in correspondence of some key infrastructures. In particular, the analysis of accelerations and decelerations of PS objects corresponding to structures affected by recent stabilization measures helps to shed new light in relation to known events that occurred in the area of interest.
[Amo.M2GARSS2022] N. Amoroso, R. Cilli, D. Iasillo, V. Massimi, A. Monaco, D. O. Nitti, R. Nutricato, S. Tangaro, A. Zilli, R. Bellotti, "PSInSAR monitoring of coastal cliffs at Torre a Mare, Apulia, Italy", 2022 IEEE Mediterranean and Middle-East Geoscience and Remote Sensing Symposium, M2GARSS 2022 - Proceedings, 2022, pp. 190–193. DOI:10.1109/M2GARSS52314.2022.9839778. Scopus:2-s2.0-85136367420. ISBN:978-166542795-1.
Coastal cliffs are subject to continuous erosion leading to huge morphological changes; their monitoring is therefore essential when they are in proximity of human infrastructures or densely inhabited regions as these changes could be responsible for severe infrastructural damages and pose human lives at risk. In this work, using PSInSAR we explored the time-series of coastal displacements at Torre a Mare, Apulia, Southern Italy. We developed a fully automated early-warning system based upon an unsupervised classification which analyzes terrain movements, outline anomalous patterns and detect possible regions at risk.
Research and results presented in this paper has been realized as part of the project 'SAPERE - Servizi Aerospaziali per le aree metropolitane', co-funded by Regione Puglia throught the call "AVVISO INNOLABS - Soluzioni innovative per problemi di rilevanza sociale".
[Ref.IGARSS2022] A. Refice, L. Partipilo, D. Capolongo, F. Bovenga, F.P. Lovergine, R. Nutricato, D.O. Nitti, "Remotely sensed detection of badland erosion using multitemporal InSAR", Proceedings of International Geoscience and Remote Sensing Symposium (IGARSS), 2022, 2022-July, pp. 5989–5992. eISSN: 2153-7003. ISBN: 978-166542792-0. DOI: 10.1109/IGARSS46834.2022.9883555. Scopus: 2-s2.0-85140396142
We observe relatively high InSAR mean coherence levels over badlands, i.e. clayey bare soil areas, on a test site in the Basilicata region, in southern Italy. Time series of InSAR coherences on cascaded short-baseline image pairs, obtained from 5-years stacks of Sentinel-1 SAR images, exhibit oscillating behaviour, with significant correlation with cumulated rainfall levels on badland areas, while on other areas with crops or spontaneous vegetation the correlation is lower, and a seasonal trend is instead statistically significant. These observations seem to point to the possibility of observing erosion phenomena over badland areas through InSAR coherence time series, which involves a significant step forward, in terms of spatial and temporal resolution, with respect to traditional measurements which require repeated topographic surveys at long intervals, or sparse in-field point measurements.
[Ref.IGARSS2022a] A. Refice, A. D’Addabbo, F.P. Lovergine, F. Bovenga, R. Nutricato, D.O. Nitti, "Improving flood monitoring through advanced modeling of Sentinel-1 multi-temporal stacks", Proceedings of International Geoscience and Remote Sensing Symposium (IGARSS), 2022, 2022-July, pp. 5881–5884. eISSN: 2153-7003. ISBN: 978-166542792-0. DOI: 10.1109/IGARSS46834.2022.9883943. Scopus: 2-s2.0-85140365510.
Multi-temporal remotely sensed data are a precious source of information for high spatial and temporal resolution flood mapping. We present a methodology for flood mapping through processing of long time series of Sentinel-1 SAR data, as well as ancillary information. A Bayesian framework is adopted to derive probabilistic maps of the presence of flood waters, through modeling of backscatter time series, based on the assumption that floods represent impulsive temporal anomalies. We illustrate some results over the Basilicata Region, in Southern Italy, recurrently subject to floods.
[Net.ANIDIS2022] A. Nettis, V. Massimi, R. Nutricato, D. O. Nitti, S. Samarelli, G. Uva, "On the Use of Satellite-Based Interferometry for Structural Monitoring of Bridge Portfolios". Procedia Structural Integrity (Open Access), Volume 44, Pages 1996 - 2003, 2022 19th ANIDIS Conference, Seismic Engineering in Italy, Turin, 11-15 September 2022, Code 188160. ISSN: 24523216, ISBN: 978-171387041-8, DOI: 10.1016/j.prostr.2023.01.255, Scopus: 2-s2.0-85159146192. WOS:001198136800253
Transport network management authorities need to address targeted monitoring and structural assessment on appropriately selected critical bridges to improve the serviceability and safety of the network optimising the involved financial budgets and resources. The multi-temporal satellite-based differential interferometry, commonly referred to as MTInSAR, is a remote-sensing technique aimed at detecting displacements of coherent scatterers on the terrestrial surface with centimetre-to millimetre-level accuracy. This paper applies an MTInSAR-based methodology for the portfolio-scale evaluation of deformation phenomena on bridges, suitable for addressing targeted sensor-based monitoring or on-site inspection plans. The methodology is applied toa case-study highway network in Roma (Italy)by using Sentinel-1 (C-band) and COSMO-SkyMed (X-band) satellite datasets. The interferometry products are processed to identify bridge-specific deformation scenarios. The MTInSAR products and the deformation scenarios related to some specific test bridges subjected to subsidence phenomena are analysed to highlight the advantages and disadvantages of the investigated approach.
The research presented in this paper is partially funded by the CONSORZIO FABREin the framework of the agreement named "Supporto tecnico-scientifico per lo sviluppo della metodologia per il censimento, ispezioni iniziali e individuazione delle Classi di Attenzione di un campione di ponti e viadotti gestiti da Anas Spa; prioritarizzazione delle operazioni di valutazione di livello 4; verifica della qualità e di omogeneità dei risultati".
Conference Abstracts
[Bov.EGU2022] F. Bovenga, A. Refice, I. Argentiero, R. Nutricato, D. O. Nitti, G. Pasquariello and G. Spilotro, "Detection of nonlinear kinematics in InSAR displacement time series for hazard monitoring", EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-26, DOI:10.5194/egusphere-egu22-26, 2022.
Multi-temporal SAR interferometry (MTInSAR), allows analysing wide areas, identifying critical ground instabilities, and studying the phenomenon evolution in a long time-scale. The identification of MTInSAR displacements trends showing non-linear kinematics is of particular interest since they include warning signals related to pre-failure of natural and artificial structures. Recently, the authors have introduced two innovative indexes for characterising MTInSAR time series: one relies on the fuzzy entropy and measures the disorder in a time series, the other performs a statistical test based on the Fisher distribution for selecting the polynomial model that more reliably approximate the displacement trend. This work reviews the theoretical formulation of these indexes and evaluate their performances by simulating time series with different characteristics in terms of kinematic (stepwise linear with different breakpoints and velocities), level of noise, signal length and temporal sampling. Finally, the proposed procedures are used for analysing displacement time series derived by processing Sentinel-1 and COSMO-SkyMed datasets acquired over Southern Italian Apennine (Basilicata region), in an area where several landslides occurred in the recent past. The MTInSAR displacement time series have been analysed by using the proposed methods, searching for nonlinear trends that are possibly related to relevant ground instabilities and, in particular, to potential early warning signals for the landslide events. Specifically, the work presents an example of slope pre-failure monitoring on Pomarico landslide, an example of slope post-failure monitoring on Montescaglioso landslide, and few examples of structures (such as buildings and roads) affected by instability related to different causes.
This work was supported in part by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, Programma Operativo Nazionale Ricerca e Innovazione (PON R&I) 2014–2020 under Project OT4CLIMA; and in part by Regione Puglia, POR Puglia FESR-FSE 204-2020 - Asse I - Azione 1.6 under Project DECiSION (p.n. BQS5153).
[Col.EGU2022] R. Colacicco, A. Refice, R. Nutricato, A. D'Addabbo, D. O. Nitti, D. Capolongo, "High spatial and temporal resolution flood monitoring through integration of multisensor remotely sensed data and Google Earth Engine processing", EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4403, https://doi.org/10.5194/egusphere-egu22-4403, 2022.
Climate change and anthropogenic impact are intensifying the frequency and intensity of extreme flood events. This is particularly worrying in the Mediterranean area, which is highly vulnerable and therefore subject to increased flood risk. The monitoring of flooded areas at high-resolution plays an important role in all phases of disaster management, from alert to the emergency and civil protection phase, up to damage assessment, for compensation and risk reduction purposes. This study aims at the multi-temporal analysis of remote sensing data, mainly radar data, through the implementation of a semi-automated system for the high-resolution mapping of river flooding effects. The objective is also to develop a system based on the fusion of different data sources and for different land cover types. The system includes an algorithm for the computation of multi-temporal, probabilistic flood maps, based on the analysis of amplitude series (in dB) of a stack of SAR images, acquired both in areas with permanent water and in areas with potential flooding. Exploiting a Bayesian inference framework, conditioned probabilities are estimated for the presence of water. The procedure relies on the temporal modelling of the SAR amplitudes time series, in order to account for seasonal and other slow temporal trends, and thus highlighting floods as events causing abrupt variations of the backscatter, lasting for a single or a few acquisitions. The methodology is particularly suited to data from sensors characterized by a high temporal frequency, such as the European Sentinel-1 constellation, whose two sensors acquire with the same geometrical configuration every 6 days over Europe. In parallel, a land use classification, at high resolution, is produced for each year within the period of acquisition of the satellite image stack (late 2014 to present) using Google Earth Engine [1]. This cloud-based platform makes it easy to access high-performance computing resources for processing geospatial data, allowing for the independent development of algorithms and subsequently specific applications. This supervised classification, achieved with the 'random forest' machine learning technique, is obtained through the combined use of SAR Sentinel 1 and optical Sentinel 2 images, over each entire year of interest. We show how the combination of these techniques can help gaining insight on the land cover, and on the expected changes of their appearance in the remotely sensed data in flooded conditions. This information can be used to improve the performance of the monitoring algorithm over various land cover scenarios and climatic settings. The procedure is tested over the Metaponto plain, in the Basilicata region (southern Italy). The proposed methodologies can however be used for other contexts affected by similar events, in the Mediterranean area and worldwide.
[Bov.RS2021] F. Bovenga, G. Pasquariello and Alberto Refice, "Statistically-Based Trend Analysis of MTInSAR Displacement Time Series", Remote Sens. 2021, 13, 2302. DOI: 10.3390/rs13122302
Current multi-temporal interferometric Synthetic Aperture Radar (MTInSAR) datasets cover long time periods with regular temporal sampling. This allows high-rate and non-linear trends to be observed, which typically characterize pre-failure warning signals. In order to fully exploit the content of MTInSAR products, methods are needed for the automatic identification of relevant changes along displacement time series and the classification of the targets on the ground according to their kinematic regime. This work reviews some of the classical procedures for model ranking, based on statistical indices, which are applied to the characterization of MTInSAR displacement time series, and introduces a new quality index based on the Fisher distribution. Then, we propose a procedure to recognize automatically the minimum number of parameters needed to model a given time series reliably within a predefined confidence level. The method, though general, is explored here for polynomial models, which can be used in particular to approximate satisfactorily and with computational efficiency the piecewise linear trends that are generally used to model warning signals preceding the failure of natural and artificial structures. The algorithm performance is evaluated under simulated scenarios. Finally, the proposed procedure is also demonstrated on displacement time series derived by the processing of Sentinel-1 data.
The authors thank GAP srl and Planetek Italia srl for providing MTInSAR time series through the Rheticus® platform. The Sentinel-1 data were provided through the Copernicus Program of the European Union. Finally, the authors thank M. Mottola for her support.
International Conference Proceedings
[Amo.IGARSS2021] A. Amodio, S. Samarelli, V. Massimi, A. Lorenzo-Alonso, A.U. Gonzalez, M. Foumelis, F. Provost, P. Bally, R. Nutricato, D. O. Nitti, "EO4SD-DRR Earth Observation to support the reconstruction and rehabilitation in the aftermaths of tsunami and earthquake", 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, 11-16 July 2021. DOI: 10.1109/IGARSS47720.2021.9554613. Scopus: 2-s2.0-85129880634. eISBN:978-1-6654-0369-6. eISSN: 2153-7003
The Earth Observation is proven to be extremely useful in the management of the aftermaths of tsunami and earthquakes. ESA-Disaster Risk Reduction (DRR) is a project within the Earth Observation for Sustainable Development (EO4SD) program aiming to demonstrate on large scale in developing countries the usefulness of Earth Observation to reduce disaster risks and to support the management of the post-event rehabilitation and reconstructions. Among the activities of the project, the ESA-DRR team, following the dramatic event of the Sulawesi earthquake (28 September 2018) supported the Indonesian authorities, through the cooperation with the Asian Development Bank (ADB), the reconstruction and rehabilitation of Palu area. The provided EO services are presented.
The work is funded by the EO4SD Disaster Risk Reduction project under the frame of ESA Earth Observation for Sustainable Development program.
[Can.Bids2021] L. Candela, A. Coletta, M. G. Daraio, R. Guarini, E. Lopinto, D. Tapete, M. Palandri, D. Pellegrino, M. Zavagli, A. Amodio, G. Ceriola, A. Vecoli, S. Mantovani, R. Nutricato, C. Giardino, "The Italian Thematic Platform CosteLab: from Earth Observation Big Data to products in support to coastal applications and downstream", Proc. of the 2021 conference on Big Data from Space (BiDS’21), 18-20 May 2021, pag. 117-120. DOI: 10.2760/125905. ISBN:978-92-76-37661-3. ISSN: 1831-9424
The Italian Space Agency (ASI) has promoted the development of the thematic platform costeLAB as a tool dedicated to monitoring, management and study of coastal areas (sea and land). costeLAB is being developed to run in a pre-operational context as an integrated system which exploits multi-mission and multi-sensor Earth Observation big data – particularly from Copernicus Sentinels and ASI's COSMO-SkyMed Synthetic Aperture Radar constellation and, in future, PRISMA – to generate products based on user-selected input parameters, without the need for large data volume transfers. costeLAB is interoperable with the Copernicus Open Access Hub and other data repositories and services. A portfolio of about 30 products (e.g. coastline, defense works, coastal habitat maps, flooding, hydrocarbon beaching, chlorophyll, wave, wind fields) is offered to support institutional, scientific and industrial users towards implementation of national policies and directives, as well as to study, experiment and develop new downstream pre-operational services for monitoring and management of coastal areas.
[Gra.OMC2021] "G. Graci, R. Nutricato, D. Nitti, V. Massimi, S. Samarelli, J. Wasowski, ""Operational Monitoring Procedures Based on Sentinel-1 SAR Data Processing to Support Oil Production Activities"", paper presented at the OMC Med Energy Conference and Exhibition, Ravenna, Italy, September 2021. Paper Number: OMC-2021-048. Published: September 28 2021. ISBN: 978-88946678-0-6.URL: https://onepetro.org/OMCONF/proceedings-abstract/OMC21/All-OMC21/OMC-2021-048/473155
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This work provides a detailed description of an operational service based on the processing of Sentinel-1 satellite SAR (Synthetic Aperture Radar) data aimed at monitoring the ground surface displacements in the Sauro valley, southern Italy, where oil production activities are in progress. The operational character of the service is ensured by (i) the maturity of the SAR data processing methodology used, which is based on Multi Temporal Interferometry (MTInSAR), and (ii) the availability of the Sentinel-1 SAR images acquired in a systematic way (1 image every 6 days) over the area of study. The procedures and tools here presented are of general applicability and can be used in other geographic regions. Furthermore, the proposed approach allows the integration of in-situ data based on GNSS measurements and on the use of corner reflectors thus enabling also the cross-validation of the ground surface displacement maps produced by the service. In particular, the complementary data from GNSS permanent stations installed at corner reflector sites demonstrated a very good agreement between GNSS and SAR measurements. This confirms the high potential of SAR interferometry in providing reliable wide-area displacement maps. More specifically, the application of these tools and procedures to the Tempa Rossa oilfield in the Sauro valley, Basilicata, allowed to deploy a modern and efficient monitoring process, complying with the Guidelines For Monitoring Seismicity, Ground Deformation And Pore Pressure In Subsurface Industrial Activities which recommend, among other things, the use of satellite methods to detect ground deformations using interferometric technologies with an accuracy of some millimeters/year.
We thank IMAGEO s.r.l. for their support with GNSS data.
[Gul.AERO2021] S. Gulati, R. Nutricato, D.O. Nitti and S. Samarelli, "Spaceborne SAR Interferometry Exploitation for Longitudinal Ground Deformation Monitoring", IEEE Aerospace Conference Proceedings, Volume 2021-March6, March 2021, Article number 9438536. DOI: 10.1109/AERO50100.2021.9438536. ISSN: 1095323X. ISBN: 978-172817436-5. Scopus: 2-s2.0-85111376392. WOS:000594576100001.
Multi-temporal Interferometric SAR (InSAR) is a promising modality for spaceborne analysis of ground and structure deformations for predictive alerting. With increasing deployments of highly capable commercial satellites offering high spectral and spatial resolution, global coverage and site revisit rates, predictive structural instability/integrity assessment is becoming accessible at a fraction of cost of aerial and ground based solutions. This paper presents an overview of the opportunities and challenges in affordably monitoring new and longstanding large buildings, monuments and ground infrastructure. This is necessitated by increasingly intense exploitation of environmental resources, hydrogeological instabilities and risk of natural disasters in environments perturbed by human activities that has created new risks. Planetek's Rheticus Displacement (RD) solution provides actionable, accurate assessment of land subsidence and slow changes. The underlying SPINUA (Stable Point Interferometry Even Over Unurbanized Areas) technique has already been shown to be robust in non- and scarcely urbanized areas. The talk will provide an overview of InSAR usage and multitemporal analysis processing chain to estimate ground displacement and velocity, including results from well-characterized distributed scatterers. New results are presented that combine Quantum Resonance Interferometry (QRI) SNR and SCR enhancement processing within RD computational pipeline for extending the reliability of displacement computations to complex, vegetated ground topography and reducing the number of ground fiducials. New results are presented on dataset acquired using ESA's Sentinel-l C-band InSAR instrument (with revisit time of 6 days) with high swath-width over a site in Southern Italy. QRI-enhanced displacement maps, compared in terms of the density of measured coherent targets and the precision of the estimated velocity, will be provided. The paper will discuss the utility of improved InSAR processing in all-weather, early warning land hazard monitoring satellite system.
[Bov.Fringe2021] F. Bovenga, G. Pasquariello, A. Refice, R. Nutricato, D. O. Nitti, M. T. Chiaradia, "Analysis Of Multi-Temporal SAR Interferometry Time Series For Warning Signal Detection", presented at ESA Fringe 2021, June 2021, online event.
Multi-temporal SAR interferometry (MTInSAR) techniques are able to derive displacement maps and displacement time series over coherent objects on the Earth, used for monitoring either geophysical ground deformation or structural instabilities. Nowadays, several datasets are available at different wavelengths, spatial resolutions, and revisit time, collectively covering long time periods (even more than 20 years). In particular, short revisit times (e.g. from Sentinel-1 and COSMO-SkyMed constellations), by improving the temporal sampling, make theoretically possible to catch high-rate and non-linear kinematics, which typically characterize warning signals related to, for instance, landslides or pre-failure of artificial infrastructures. However, MTInSAR algorithms generally fit the displacement signal by using a linear model, which is computationally convenient, and also, more robust than higher-order models for what concerns the errors affecting the InSAR phase. Moreover, the analysis of the MTInSAR products is often performed by only considering the mean displacement rate, computed over the monitoring period, which is the information typically displayed on the displacement maps. Therefore, in order to fully exploit the content of MTInSAR products, methods are needed for automatically identifying relevant changes along displacement time series, and, consequently, classifying the targets on the ground according to their kinematic regime. This also allows performing a more reliable ground deformation spatial analysis, by distinguishing among spatial patterns of different kinematics (linear, bi-linear, quadratic, discontinuous and periodic). Recently, approaches have been proposed to tackle this problem, which use different strategies, based on Principal Component Analysis (Chaussard et al., 2014), statistical tests (e.g., Berti et al., 2013), or more sophisticated probabilistic multiple hypotheses testing (Chang and Hanssen, 2016). Our work proposes a new set of rules based on statistical characterization of displacement time series, which allows, under certain constraints, recognising automatically different kinematic classes, and estimating the relevant parameters useful for target characterization in time. We introduce a new statistical test based on the Fisher distribution aimed at evaluating the reliability of a displacement model with a certain statistical confidence. We also studied the reliability of other tests already introduced in literature and used for comparing two different models, namely the Akaike Information Criterion, the Bayesian Information Criterion, and the Fisher test. A performance analysis has been carried out by simulating time series with different characteristics in terms of kinematic (stepwise linear with different breakpoints and velocities), level of noise, signal length and temporal sampling. The displacement estimations performed by using the different tests have been compared. Finally, a procedure for selecting the optimum displacement model has been defined according to the output of the performance analysis. The procedure has been also tested by using real datasets coming from Sentinel-1 and COSMO-SkyMED missions, and covering areas affected by non-linear displacements and slope failures.
This work was supported in part by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, Programma Operativo Nazionale Ricerca e Innovazione (PON R&I) 2014–2020 under Project OT4CLIMA; and in part by Regione Puglia, POR Puglia FESR-FSE 204-2020 - Asse I - Azione 1.6 under Project DECiSION (p.n. BQS5153).
[Bov.SPIE2021] F. Bovenga, A. Refice, G. Pasquariello, R. Nutricato, D. Nitti, "Identification and analysis of nonlinear trends in InSAR displacement time series". Proceedings Volume 11861, Microwave Remote Sensing: Data Processing and Applications; 118610G (2021). DOI: 10.1117/12.2600135 (online only)
Multi-temporal SAR interferometry (MTInSAR) allows analysing wide areas, identifying critical ground instabilities, and studying the phenomenon evolution in a long time-scale. Nowadays satellite SAR constellations provide datasets covering time periods of several years with short revisit times, which allow investigating ground displacements showing non-linear kinematics. These are particularly interesting since they include warning signals related to pre-failure of natural and artificial structures. Recently, approaches have been proposed for recognising and analysing nonlinear displacements, which use different strategies. The authors have introduced two innovative indexes for characterising MTInSAR time series: one relies on the fuzzy entropy and measures the disorder in a time series, the other performs a statistical test based on the Fisher distribution for selecting the polynomial model that more reliably approximate the displacement trend. This work reviews the theoretical formulation of these indexes and evaluate their performances by simulating time series with different characteristics in terms of kinematic, level of noise, signal length and temporal sampling. Finally, the proposed procedures are used for analysing displacement time series derived by processing real datasets acquired by both Sentinel-1 and COSMO-SkyMed constellations. In particular the hilly villages of Pomarico and Montescaglioso have been investigated, which are located in Southern Italian Apennine (Basilicata region), in an area where several landslides occurred in the recent past, causing damages to houses, commercial buildings, and infrastructures. The MTInSAR displacement time series have been analysed by using the proposed methods, searching for nonlinear trends that are possibly related to relevant ground instabilities and, in particular, to potential early warning signals for the landslide events affecting Mtescaglioso in 2013 and Pomarico in 2019.
This work was supported in part by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, Programma Operativo Nazionale Ricerca e Innovazione (PON R&I) 2014–2020 under Project OT4CLIMA.
[Was.IAEG2021] J. Wasowski, "Recent advances in Remote Sensing for use in Engineering Geology", keynote lecture at 3rd European Regional Conference of IAEG, 6-10 Oct 2021, Athens, Greece. URL: https://euroengeo2020.org/
Sentinel-1 and COSMO-SkyMed images furnished, respectively, by ESA and ASI (European and Italian Space Agencies). Raffaele Nutricato and Davide Nitti of GAPsrl (Bari, Italy) provided radar data processing through SPINUA algorithm. Thanks also to Daniele Giordan and Paolo Allasia of CNR-IRPI for feedback on drones.
[Amo.RS2020] N. Amoroso, R. Cilli, L. Bellantuono, V. Massimi, A. Monaco, D. O. Nitti, R. Nutricato, S. Samarelli, N. Taggio, S. Tangaro, A. Tateo, L. Guerriero and R. Bellotti, "PSI clustering for the assessment of underground infrastructure deterioration", Remote Sensing 2020, 12(22), pp. 1–16, 3681. DOI: 10.3390/rs12223681. Scopus: 2-s2.0-85096099755. WOS: 000594576100001. eISSN: 2072-4292. IF(5 years):5.353 (Source: WOS).
Remote sensing images find application in several different domains, such as land cover or land usage observation, environmental monitoring, and urbanization. This latter field has recently witnessed an interesting development with the use of remote sensing for infrastructural monitoring. In this work, we present an analysis of Sentinel-1 images, which were used to monitor the Italian provinces of Bologna and Modena located at the Emilia Region Apennines foothill. The goal of this study was the development of a machine learning-based detection system to monitor the deterioration of public aqueduct infrastructures based on Persistent Scatterer Interferometry (PSI). We evaluated the land deformation over a temporal range of five years; these series feed a k-means clustering algorithm to separate the pixels of the region according to different deformation patterns. Furthermore, we defined the critical areas as those areas where different patterns collided or overlapped. The proposed approach provides an informative tool for the structural health monitoring of underground infrastructures.
Authors would like to thank IT resources made available by ReCaS, a project funded by the MIUR (Italian Ministry for Education, University and Re-search) in the “PON Ricerca e Competitività 2007–2013-Azione I-Interventi di rafforzamento strutturale” PONa3_00052, Avviso 254/Ric, University of Bari. This paper has been supported by the DECiSION (Data-drivEn Customer Service InnovatiON) project co-funded by the Apulian INNONETWORK program.
[Mol.RS2020] M. G. Molfetta, M. F. Bruno, L. Pratola, A. Rinaldi, A. Morea, G. Preziosa, D. Pasquali, M. Di Risio and M. Mossa, "A Sterescopic System to Measure Water Waves in Laboratories", Remote Sensing 2020, 12(14), 2288, 16 July 2020. DOI: 10.3390/rs12142288. Scopus: 2-s2.0-85088659223. WOS:000554231200001. ISSN: 2072-4292. IF(5 years):5.001 (Source: MPDI).
A new system for estimating the synthetic parameters of sea states during physical investigations has been implemented. The technique proposed herein is based on stereographic analysis of digital images acquired with optical sensors. A series of ad hoc floating markers has been made and properly moored to the bottom of a large wave tank to estimate the synthetic parameters of generated waves. The implemented acquisition system and the proposed algorithm provide automatic recognition of all markers by a pair of optical sensors that synchronously captures their instantaneous location and tracks their movements over time. After transformation from the image to the real-world coordinates, water surface elevation time series have been obtained. Several experimental tests have been carried out to assess the feasibility and reliability of the proposed approach. The estimated wave synthetic parameters have been then compared with those obtained by employing standard resistive probes. The deviation were found to be equal to ~6% for the significant wave height and 1% for peak, mean, and significant wave periods.
New radar satellites provide global coverage and the possibility of long-term, regular frequency (days-weeks) surface displacement measurements through the application of high precision multi-temporal InSAR (Synthetic Aperture Radar Interferometry) techniques. This represents an excellent opportunity to investigate and improve our understanding of the behavior of extremely slow landslides, as well as of the long- to short-term controls of their activity. In urban settings, such landslides deserve special attention, as their cumulative movements can cause significant socio-economic damage. Here, we re-examine the case of a long-lived, deep-seated landslide in the Apennine Mountains (Italy) which was urbanized between the late 1970s and early 2000s. The case provides a rare opportunity to highlight the benefits of the integrated analysis of long-term (several years) borehole inclinometer measurements with 15 years of multi-temporal InSAR displacement data. We present evidence of the landslide composite nature and asymmetry, and draw attention to the recent period of accelerated movement that coincided with the foot failure event. This helps constraining the interpretation of the borehole and InSAR data and demonstrating the predominantly rotational landslide mechanism. We show how a detailed analysis of sparse inclinometer and more spatially continuous InSAR measurements, when combined with local rainfall records, can reveal long- to short-term patterns of temporal variability in landslide motions and allow anticipating the consequences of future landslide activity.
Sentinel-1 and ENVISAT data are provided by ESA (European Space Agency). We thank Raffaele Nutricato and Davide Oscar Nitti of GAPsrl for providing InSAR processing through SPINUA algorithm, and Fabio Bovenga, Salvatore Galicchio, Giuseppe Rampino, and Francesca Santaloia for useful discussions. Constructive comments by the editor and an anonymous reviewer are much appreciated.
Conference Abstracts
[Ref.EGU2020] A. Refice, F. Bovenga, G. Pasquariello, I. Argentiero, G. Spilotro, R. Nutricato, D. O. Nitti, and M. T. Chiaradia, "MTInSAR long-term monitoring of nonlinear slope instabilities on hilltop villages in Southern Italy", Abstracts proceedings EGU 2020, Vienna, Austria, 04-08 May 2020. Abstract ID: EGU2020-19740, eISSN: 1607-7962. URL: https://meetingorganizer.copernicus.org/EGU2020/EGU2020-18740.html, DOI: 10.5194/egusphere-egu2020-18740
Multi-temporal SAR interferometry (MTInSAR) provides mean displacement maps and displacement time series over coherent objects on the Earth surface, allowing analysis of wide areas to identify ground deformations, and studying evolution of displacement phenomena over long time scales. MTInSAR techniques have proven very useful for detecting and monitoring also slope instabilities. Nowadays, several satellite missions are available providing InSAR data at different wavelengths, spatial resolutions, and revisit times. The Italian X-Band COSMO-SkyMed constellation acquires data with spatial resolution reaching metric values, and provides revisit times of up to a few days, leading to an increase in the density of the measurable targets, thus improving the monitoring of local scale events as well as the detection of non-linear displacements. The recent Sentinel-1 Cband mission from the European Space Agency (ESA) provides a spatial resolution comparable to previous ESA SAR missions, but a nominal revisit time reduced to 6 days. By offering regular globalscale coverage, better temporal resolution and freely available imagery, Sentinel-1 improves the performance of MTInSAR for ground displacement investigations. In particular, the short revisit time allows a better time series analysis by improving the temporal sampling and thus the chances to catch pre-failure signals characterised by high rate and non-linear behaviour. Moreover, it allows collecting large data stacks in a short time periods, thus improving MTInSAR performance in emergency (post-event) scenarios. These characteristics are very promising for early warning of slope failure events and monitoring subsequent displacements trends. In this work, we present the results obtained by using both COSMO-SkyMed and Sentinel-1 data for investigating the ground stability of hilly villages located in Southern Italian Apennine (Basilicata region). In the area of interest, several landslides occurred in the recent past (e.g. Montescaglioso in 2013) and more recently (e.g. Pomarico in 2019), causing extensive damage to houses, commercial buildings, and infrastructures. SAR datasets acquired by COSMO-SkyMed and Sentinel-1 from both ascending and descending orbits have been processed by using the SPINUA MTInSAR algorithm, in order to exploit the potentials of these two satellite missions to investigate ground displacements related to slope instabilities. Mean velocity maps and displacement time series have been analysed looking, in particular, for non-linear trends that are possibly related to relevant ground instability episodes and, thanks to the high spatial resolution, useful in terms of early warning, in the case of rigid soil masses. Results are presented and discussed in relation to known events occurred in the area of interest.
Research carried out in the framework of project OT4CLIMA, funded by the Italian Ministry of Education, University and Research, D.D. 2261 del 6.9.2018, PON R&I 2014-2020 and FSC, and project DECiSION (p.n. BQS5153), funded by Regione Puglia, POR Puglia FESR-FSE 204-2020 - Asse I - Azione 1.6.
Other poster/slideshow presentations
[Pag.EngEdu2020] M. Pagano, S. Samarelli, S. Bollanos, V. Massimi, D. O. Nitti, G. Ortolano, “Geological risk monitoring of road network by use of combined Multi-Temporal InSAR and GIS-based derived information: the example of Giarre (Eastern Sicily, Italy)”, 5th Annual International Conference on Engineering Education & Teaching, 1-4 June 2020, Athens, Greece. ISBN: 978-960-598-337-6. URL: https://www.atiner.gr/2020/Pagano.pdf
The present work shows how the contribution of the satellite infrastructure monitoring performed through the Rheticus® cloud platform integrated with specific GIS based derived information tools can be useful for monitoring the geological risk in a road network. The adopted monitoring infrastructure capable of assigning a level of geological risk to the different roads of the municipal area of Giarre (eastern Sicily, Italy), was designed with the aim of creating semi-automated pre-alerting systems , able to delineate potentially risky sites. This cyber infrastructure is based on computation of vulnerability to geological, hydrological and geomorphological issues and on the occurrence of active faults, introducing successively the exposure computation as a function of the vehicles flow. The identification of the potential dangerous areas was done by collecting bibliographic data and consulting online databases such as the IFFI project (/www.progettoiffi.isprambiente.it/), the PAI cartography www.sitr.regione.sicilia.it/pai/pai/) and the Civil Protection department database (www.protezionecivile.gov.it/). The boundaries of some areas were redefined through photo interpretation process and through the harmonization of much data in a GIS project, such as geological, geomorphological and hydrogeological maps. Some derived maps have also been created: TIN model, hillshade, slope and aspect charts. These charts are important ancillary data to support the interpretation of the velocities and displacements values provided by the MTI measurements. Exposure is another fundamental parameter that significantly contributes to the risk value. In a road network, the exposure value corresponds to vehicles flow density in each road. This value was calculated by creating two models: the first one is based on a source destination matrix, built starting from demographic map and from a collection of every point of interest, weighted according to their level of attractiveness; the second one is based on Google Traffic data and takes into consideration the variability of traffic values at different times. One of the most important phases of the work concerns the processing of the Sentinel 1 images performed through the Rheticus® cloud platform that implements the SPINUA Multi Temporal InSAR (MTI) algorithm and the analysis with the additional GIS derived information. This study was carried out in collaboration with two of the leading companies in this sector, Planetek Italia S.r.l. (Bari) and Planetek Hellas E.P.E (Athens); tE.P.E (Athens); the aim is to monitor and identify the displacements of the earth"s surface and to try to prevent landslides and ground instability, which can damage infrastructures like buildings and roads. The radar interpretation process, through the analysis of Vlos anos and the displacements time series of the two different geometries (descending and ascending orbits), crossing the data with the ancillary ones described above, allowed to identify the areas in elevation and those in subsidence. So, the study was focused on the search for possible precursor elements of instability phenomena and the evaluation of the state of activity of the already recognized instability areas. In this view, the use of MTI technique represents an important contribution to redefine the dangerous areas identified in the first phase of the work, increasing the accuracy of the final risk definition for the road infrastructure.
[Bru.Sensors2019] M.F. Bruno, M.G. Molfetta, L. Pratola, M. Mossa, R. Nutricato, A. Morea, D.O. Nitti and M.T. Chiaradia, "A Combined Approach of Field Data and Earth Observation for Coastal Risk Assessment", SENSORS, Vol. 19(6), 1399. 2 March 2019. DOI: 10.3390/s19061399. Scopus: 2-s2.0-85063663135. WOS:000465520200088. ISSN: 1424-8220. IF(2018):3.031 (Source: WOS). IF(5 years):3.302 (Source: WOS).
The traditional approach for coastal monitoring consists in ground investigations that are burdensome both in terms of logistics and costs, on a national or even regional scale. Earth Observation (EO) techniques can represent a cost-effective alternative for a wide scale coastal monitoring. Thanks to the all-weather day/night radar imaging capability and to the nationwide acquisition plan named MapItaly, devised by the Italian Space Agency and active since 2010, COSMO-SkyMed (CSK) constellation is able to provide X-band images covering the Italian territory. However, any remote sensing approach must be accurately calibrated and corrected taking into account the marine conditions. Therefore, in situ data are essential for proper EO data selection, geocoding, tidal corrections and validation of EO products. A combined semi-automatic technique for coastal risk assessment and monitoring, named COSMO-Beach, is presented here, integrating ground truths with EO data, as well as its application on two different test sites in Apulia Region (South Italy). The research has shown that CSK data for coastal monitoring ensure a shoreline detection accuracy lower than image pixel resolution, and also providing several advantages: low-cost data, a short revisit period, operational continuity and a low computational time.
CSK Products of the Italian Space Agency (ASI), delivered by ASI under a license to use. This research was partially funded by the FP7 EU projects COCONET (http://www.coconet-fp7.eu).
[Ref.Landslides2019] "A. Refice, L. Spalluto, F. Bovenga, A. Fiore, M.N. Miccoli, P. Muzzicato, D.O. Nitti, R. Nutricato, G. Pasquariello, ""Integration of persistent scatterer interferometry and ground data for landslide monitoring: the Pianello landslide (Bovino, Southern Italy)"". Landslides, Vol. 16(3), 14 March 2019, Pages 447-468. DOI: 10.1007/s10346-018-01124-0. Scopus:2-s2.0-85059848014. WOS:000461573100001. ISSN: 1612-510X. eISSN: 1612-5118. IF(2018): 4.252 (Source: WOS). IF(5 years):4.667 (Source: WOS)
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We present an example of integration of persistent scatterer interferometry (PSI) and in situ measurements over a landslide in the Bovino hilltop town, in Southern Italy. First, a wide-area analysis of PSI data, derived from legacy ERS and ENVISAT SAR image time series, highlighted the presence of ongoing surface displacements over the known limits of the Pianello landslide, located at the outskirts of the Bovino municipality, in the periods 1995-1999 and 2003-2008, respectively. This prompted local authorities to install borehole inclinometers on suitable locations. Ground data collected by these sensors during the following years were then compared and integrated with more recent PSI data from a series of Sentinel-1 images, acquired from March 2014 to October 2016. The integration allows sketching a consistent qualitative model of the landslide spatial and subsurface structure, leading to a coherent interpretation of remotely sensed and ground measurements. The results were possible thanks to the synergistic operation of local authorities and remote sensing specialists, and could represent an example for best practices in environmental management and protection at the regional scale.
Copernicus Sentinel-1 data are provided by European Space Agency (ESA). ENVISAT and ERS data provided by ESA Category-1 project nos. 2653 and 5367. This work was performed in the framework of the agreement "Convenzione operativa per lo studio del dissesto del suolo nel sub-appennino dauno," CUP H38C16000050008. We thank two anonymous reviewers for their insightful comments and mostly constructive criticisms who helped in improving the manuscript. This research is funded by the Italian Ministry of University and Research (MIUR) in the framework of "APULIA SPACE" project (PON03PE_00067_6), PON Ricerca e competitività 2007–2013.
International Conference Proceedings
[Bru.Metrosea2018] M.F. Bruno, M.G. Molfetta, M. Mossa, L. Pratola, R. Nutricato, A. Morea, D.O. Nitti and M.T. Chiaradia, "Remote sensed and in situ data: An integrated approach for Coastal Risk Assessment". 2018 IEEE International Workshop on Metrology for the Sea; Learning to Measure Sea Health Parameters, MetroSea 2018 - Proceedings, 1 March 2019, Article number 8657899, Pages 13-17. DOI: 10.1109/MetroSea.2018.8657899. Scopus: 2-s2.0-85063864317. WOS:000463192900003. ISBN: 978-153867644-8.
The continuous monitoring of coastal areas is a necessary condition for a timely assessment of shoreline erosion phenomena. The traditional approach consists in ground investigations that are impractical in terms of costs and logistics, on a national or even regional scale. Earth Observation (EO) techniques can represent a cost-effective alternative for a wide-scale Coastal Zone Management. Thanks to the all-weather day/night radar imaging capability and to the nationwide acquisition plan named MapItaly, devised by the Italian Space Agency and active since 2010, COSMO-SkyMed constellation is able to provide X-band images covering the Italian territory with a best effort revisit time of 16 days. However, any remote sensing approach must be accurately calibrated and corrected for the actual meteo-marine conditions. Therefore, in situ data are essential for proper EO data selection, tidal corrections and validation of EO products. An integrated semi-automatic technique for coastal risk assessment and monitoring, named COSMO-Beach, is presented here, with a particular emphasis on the ground truths provided in input to the implemented processing chain, as well as its application on two different test sites in Apulia Region (South Italy).
[Bov.LP2019] F. Bovenga, A. Belmonte, A. Refice, G. Pasquariello, R. Nutricato, D.O. Nitti, M.T. Chiaradia, "Performance analysis of multi-temporal and multi-frequency SAR interferometry". Poster presentation, ESA Living Planet 2019, 13-17 May 2019, Milan, Italy.
Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. A new interesting opportunity is provided by Sentinel-1, which has a spatial resolution comparable to previous ESA C-band sensors, and revisit times improved up to 6 days. According to these different SAR space-borne missions, the present work discusses current and future opportunities of Multi-temporal InSAR (MTI) applications to ground instability monitoring. The mission parameters, which impact on the quality of the MTI products, are the wavelength of the SAR signal (decreasing from L, ~23 cm, to C, ~5.5 cm, to X band, ~3.1 cm), the revisit time, the spatial resolution, and the orbital tube. The figures that allow estimating the quality of the displacement maps are: the number of measurable coherent targets on the grounds (e.g. the PS density), the maximum detectable displacement velocity, the minimum number of processed images or the observation time span needed to derive reliable products, and the noise affecting both the final displacement and residual height estimation. Issues related to coherent target detection, mean velocity precision and product geo-location are addressed through a simple theoretical model assuming backscattering mechanisms related to point scatterers. In particular, a comparative analysis is carried out, aimed at addressing specific advantages and limitations of different satellite missions. This performance analysis may provide support for the SAR data selection, or for the definition of the geometrical and radiometrical configurations of future missions. For instance, high resolution data are found to increase the density of coherent targets, thus improving the monitoring of local scale events. Short X-band wavelengths improve the sensitivity to displacements. Short revisit times allow collecting large data stacks in short times, and improve the temporal sampling, thus increasing the chances to catch pre-failure signals (high-rate, nonlinear signals). The precision of the displacement rate detection depends on the number of images and on the phase noise, while the precision of the residual height depends also on the orbital tube size. These relations have been formalized in a conceptual model, by assuming typical values for target characteristics such as persistent scatterer shape and signal to clutter ratio. The model allows to derive quantitative, although indicative predictions for the performance of several missions (present and future), based on the above mentioned mission parameters. In particular, for example, Sentinel-1 (S1), which will provide SAR data for the next years with short revisit times, results able to provide reliable displacement estimations at large scale, and in quite limited observation time spans (accuracy of about 1 mm/y for time series covering 1 year). However, the narrow orbital tube size, may limit the height precision, and consequently the geo-location quality (e.g. vertical precision above 20 cm with observation time span below 12 months, assuming S1- A/B 12 days repetitivity). X-band missions as COSMO-SkyMed (CSK) or TerraSAR-X, show the best performance in terms of precision on the estimated mean velocity and height, especially for limited observation time spans (e.g. precision of 2 mm/y for velocity and 3 cm for height, with 12 months of observation time and 1 acquisition per month). By considering the forthcoming new SAR missions (e.g. SAOCOM, Tandem-L, NISAR, RADARSAT Constellation Mission, PAZ, COSMOSkyMED- SG, TerraSAR-X-NG), the resolutions and revisit times will be able to further improve the interferometric performances. The paper also presents examples of multi-sensor ground instability investigation. More than 20 years of MTI SAR data have been processed, coming from both legacy ERS and ENVISAT missions, and last-generation RADARSAT-2, COSMO-SkyMed, and Sentinel-1 sensors. Moreover, a comparison has been performed between the outcomes of the model developed for assessing the MTI product precision, and the results obtained by processing the real datasets from ERS, ENVISAT, RADARSAT-2, COSMO-SkyMed and Sentinel-1 missions available for a real test case.
Work supported by the project "APULIA SPACE" (PON03PE_00067_6), PON Ricerca e competitività 2007-2013.
[Ref.LP2019] A. Refice, F. Bovenga, G. Pasquariello, L. Spalluto, A. Fiore, N. Miccoli, P. Muzzicato, D.O. Nitti, R. Nutricato, "Towards operational integration of remotely sensed MTI SAR data and ground sensors information within environmental management best practices: the Daunia case (Southern Italy)". Poster presentation, ESA Living Planet 2019, 13-17 May 2019, Milan, Italy.
"The huge and increasing quantity of high temporal and spatial resolution remote sensing data, especially from the European Copernicus Sentinel sensor constellations, calls for a more systemic and capillary integration of remotely sensed information with knowledge of the situation on the ground. This is especially true in the case of environmental hazard, where the need to fruitfully exploit the synoptic information coming from space sensors within remedial and protection actions by local authorities is more pressing. In this direction, the promotion of interactions between remote sensing specialists and local authorities personnel, leading to good practices and operational protocols of interventions, can be considered a viable solution for virtuous environmental management.
We present an example of integration of information from multi-temporal interferometry (MTI) techniques applied to time series of synthetic aperture radar (SAR) data, and in situ measurements over landslides afflicting several small hilltop towns in the Daunia region, Southern Italy. In a first joint project in 2008, a wide-area analysis of persistent scatterers (PS), derived from legacy ESA ERS and ENVISAT SAR image time series, highlighted the presence of ongoing surface displacements over several known landslides. An example is the Pianello landslide, located at the outskirts of the Bovino municipality, where movements were detected in the periods 1995-1999 and 2003-2008, respectively. This prompted local authorities to install boreholes equipped with inclinometers and other sensors on suitable locations. Ground data collected by these sensors during the following years were then compared with more recent PSI data from series of Sentinel-1 images, available from 2014. The integration of wide area MTI surface displacement information, projected onto the sub-vertical satellite line of sight, with pointwise subsurface vector displacement profile measurements in the horizontal plane, collected by inclinometers, as well as other data such as ground water levels measured from piezometers, allows, in several cases, sketching consistent models of a landslide spatial and subsurface structure, leading to a coherent interpretation of remotely sensed and ground measurements. In the above-mentioned case of the Bovino landslide, the limits of the affected area were updated, and the trend and depth of the rupture shear surface was inferred within a coherent picture of the whole mass movement phenomenon. For what concerns the temporal dimension, the integration of ground and satellite measurements time series may allow e.g. to optimize resources to increase the precision of warnings for landslide reactivations. This ongoing collaboration between local authorities and remote sensing specialists is being extended to other town centers in the Daunia area, and could thus represent an example for best practices in environmental management and protection at the regional scale."
Part of this research was funded by the Italian Ministry of University and Research (MIUR) in the framework of the "APULIA SPACE" project (PON03PE_00067_6), PON Ricerca e competitività 2007-2013. Copernicus Sentinel-1 data are provided by European Space Agency (ENVISAT and ERS data provided by ESA Category 1 projects N 2653 and 5367 Work performed in the framework of the agreement "Convenzione operativa per lo studio del dissesto del suolo nel sub appennino dauno", CUP: H38C16000050008.
[Bov.SPIE2019] F. Bovenga, A. Refice, G. Pasquariello, G. Spilotro, R. Nutricato, D. O. Nitti, M. T. Chiaradia, I. Argentiero, R. Pellicani, "Investigating slope instabilities through SAR interferometry: examples on hilly villages in Southern Italy". To be presented at SPIE Remote Sensing 2019, Sept. 11, 2019, Strasbourg, France.
Multi-temporal SAR interferometry (MTInSAR), provides both mean displacement maps and displacement time series over coherent objects on the Earth, and it is used for detecting and monitoring slope instabilities. Nowadays, several satellite missions are available providing data at different wavelengths, spatial resolutions, and revisit time. The high-resolution X-Band COSMO-SkyMed constellation, acquires data with metric spatial resolution, and provides revisit times of up to a few days, leading to an increase in the density of the measurable targets, thus improving the monitoring of local scale events as well as the detection of non-linear displacements. The recent Sentinel-1 C-band mission from the ESA, provides a spatial resolution comparable to the previous ESA missions, but a nominal revisit time reduced to 6 days, resulting very promising for early warning of slope failure events and monitoring subsequent displacements trends. In this work, we present the results obtained by using both COSMO-SkyMed and Sentinel-1 data for investigating the ground stability of hilly villages located in Southern Italian Apennine. In the area of interest, several landslides occurred in the recent past (e.g. on Montescaglioso in 2013) and also very recently (e.g. on Pomarico in 2019), causing damages to houses, commercial buildings, and infrastructures. SAR datasets acquired by COSMO-SkyMed and Sentinel-1 from both ascending and descending orbits have been processed by using SPINUA MTInSAR algorithm, in order to exploit the potentials of these two satellite missions to investigate ground displacements related to the slope instabilities. Mean velocity maps and displacement time series have been analysed looking, in particular, to non-linear trends that are possibly related to relevant ground instabilities and, thanks to the high spatial resolution, useful in terms of early warning, in the case of rigid soil masses. Results are presented and discussed in relation to the well know events occurred in the area of interest.
[Bel.IAEG2019] A. Belmonte, F. Bovenga, A. Refice, G. Pasquariello, R. Nutricato, D. O. Nitti, M. T. Chiaradia, C. Marzo, P. Manzari, G. Spilotro, R. Pellicani, “Analisi e Monitoraggio di versanti attraverso utilizzo di piattaforme aeree senza pilota (UAV) e tecniche interferometriche PS”. Workshop “L’uso di droni e laser scanner in applicazioni ambientali e geologico-ingegneristiche”, organizzato dalla IAEG Italia, in collaborazione con il Dipartimento di Scienze della Terra e Geoambientali dell’Università degli Studi di Bari, 25 Ottobre 2019.
[Sam.SAIE2019] S. Samarelli, R. Nutricato, "Safeway: Il satellite a supporto delle verifiche di stabilità di strade e ferrovie", Convegno SAIE: "Infrastrutture e territorio, diagnosi e monitoraggio, gestione dei rischi, opere e innovazione". Bari, 24 Ottobre 2019.
[Bov.Sensors2018] F. Bovenga, A. Belmonte, A. Refice, G. Pasquariello, R. Nutricato, D.O. Nitti, M.T. Chiaradia, "Performance analysis of satellite missions for multi-temporal SAR interferometry". Sensors (Switzerland), Vol. 18(5), May 2018, Article number 1359. DOI: 10.3390/s18051359. Scopus:2-s2.0-85046150799. WOS:000435580300058. eISSN: 1424-8220. IF(2018): 3.031 (Source: WOS). IF(5 years):3.302 (Source: WOS)
Multi-temporal InSAR (MTI) applications pose challenges related to the availability of coherent scattering from the ground surface, the complexity of the ground deformations, atmospheric artifacts, and visibility problems related to ground elevation. Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. A new and interesting opportunity is provided by Sentinel-1, which has a spatial resolution comparable to that of previous ESA C-band sensors, and revisit times improved by up to 6 days. According to these different SAR space-borne missions, the present work discusses current and future opportunities of MTI applications in terms of ground instability monitoring. Issues related to coherent target detection, mean velocity precision, and product geo-location are addressed through a simple theoretical model assuming backscattering mechanisms related to point scatterers. The paper also presents an example of a multi-sensor ground instability investigation over Lesina Marina, a village in Southern Italy lying over a gypsum diapir, where a hydration process, involving the underlying anhydride, causes a smooth uplift and the formation of scattered sinkholes. More than 20 years of MTI SAR data have been processed, coming from both legacy ERS and ENVISAT missions, and latest-generation RADARSAT-2, COSMO-SkyMed, and Sentinel-1A sensors. Results confirm the presence of a rather steady uplift process, with limited to null variations throughout the whole monitored time-period.
Copernicus Sentinel data are provided by ESA. ENVISAT and ERS data provided by European Space Agency Category-1 project N. 5367, "Subsidence monitoring in Daunia and Capitanata (Puglia Region, Italy) through multi-temporal point-target DInSAR techniques". RADARSAT-2 Data and Products @ MacDonald, Dettwiler and Associates Ltd. 2014\u2014All Rights Reserved. RADARSAT is an official trademark of the Canadian Space Agency. COSMO-SkyMed data are provided by ASI (Agenzia Spaziale Italiana) in the framework of the "Sperimantazione di dati COSMO-SkyMed per lo studio di deformazioni del suolo" research project. Finally, authors thank anonymous reviewers for their fruitful comments. This research was funded by the Italian Ministry of University and Research (MIUR) in the framework of "APULIA SPACE" project (PON03PE_00067_6), PON Ricerca e competitività 2007-2013.
[Was.IIS2018] "J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti and M. T. Chiaradia, ""Advanced satellite radar interferometry for deformation monitoring
and infrastructure control in open-cast mines and oil/gas fields"", Innovative Infrastructure Solutions, (2018) 3:68. DOI: 10.1007/s41062-018-0176-x. Scopus:2-s2.0-85057853423. WOS:000445755300001. ISSN: 2364-4176 (print version). ISSN: 2364-4184 (electronic version). IF: 0.87 (Year: 2018 - Source: https://bit.ly/2Kbvy3g)
"
We focus on the use of advanced multi-temporal interferometry (MTI) for mapping and monitoring of ground deformations caused by open-cast mining and hydrocarbon production. We also show how MTI can be exploited to monitor the stability of infrastructure in adjacent areas. Open-cast mines represent a good target for MTI, because they are (1) often very large (from few to tens of km2); (2) free of or covered by sparse vegetation; (3) require long-term regular monitoring. The operational deformation monitoring via MTI can now rely on free of charge medium-resolution Sentinel-1 data, consistently and regularly acquired by the European Space Agency (ESA) since 2014. To illustrate the application potential of MTI based on Sentinel-1 data, we present the case study of the Belchatow mine (Poland), one of the largest open-cast mines in Europe. We stress that thanks to wide-area coverage; space-borne MTI represents a cost-effective approach to monitoring ground/slope instability hazards in large open pits, as well as the stability of the associated engineering structures and facilities. On-land oil and gas fields are also often huge and ground deformations induced by their exploitations can be profitably targeted by MTI. This is illustrated through an example of MTI application from the Middle East that relies on high-resolution (3 m) radar data. The example highlights the possibility of obtaining extremely dense (spatially continuous) information, which is important for monitoring complex ground deformations caused by oil field exploitation.
Sentinel-1 and TerraSAR-X data provided, respectively, by the European Space Agency (ESA) and German Space Agency (DLR).
[Ref.Springer2018] A. Refice, A. D’Addabbo, F. P. Lovergine, K. Tijani, A. Morea, R. Nutricato, F. Bovenga, and D. O. Nitti (2018) "Monitoring Flood Extent and Area Through Multisensor, Multi-temporal Remote Sensing: The Strymonas (Greece) River Flood". In: Refice A., D'Addabbo A., Capolongo D. (eds) Flood Monitoring through Remote Sensing, pp. 101-113. Springer Remote Sensing/Photogrammetry. Springer, Cham. DOI: 10.1007/978-3-319-63959-8_5. Print ISBN: 978-3-319-63958-1. Online ISBN: 978-3-319-63959-8
Satellite monitoring of flood events at high spatial and temporal resolution is considered a difficult problem, mainly due to the lack of data with sufficient acquisition frequency and timeliness. Typically, cloudy weather conditions associated with floods obstacle the propagation of e.m. waves in the optical spectral range, forbidding acquisitions by optical sensors. This problem is not present for longer wavelengths, so that radar imaging sensors are recognized as viable solutions for long-term flood event monitoring. In selected cases, however, weather conditions may remain clear for sufficient amounts of time, enabling monitoring of the evolution of flood events through long time series of satellite images, both optical and radar. In this contribution, we present a case study of long-term integrated monitoring of a flood event which affected part of the Strymonas river basin, a transboundary river with source in Bulgaria, which flows then through Greece up to the Aegean Sea. The event started at the beginning of April 2015, due to heavy rain, and the flooded areas lasted up to the beginning of September. Due to the arid climate characterizing the area in this period of the year, weather conditions were cloud-free for most of the time interval covering the event. We collected remotely sensed data, including one high-resolution, X-band, COSMO-SkyMed and several C-band, Sentinel-1 SAR, and optical Landsat 8 images of the area. The SAR backscatter and optical NDVI maps were thresholded to obtain binary flood maps for each day. Threshold values for microwave and optical data were calibrated by comparing one SAR and one optical image acquired on the same date. Results allow to draw a multi-temporal map of the flood evolution with high temporal resolution. The extension of flooded area can also be tracked in time, allowing post-flood recovery monitoring, as well as to envisage future testing of evapotranspiration/absorption models.
The work is partly supported by the Apulia Space Project (PON-REC 2007–2013, C.N. PON03PE_00067_6). Sentinel-1 imagery is provided by the European Space Agency (ESA). COSMO-SkyMed imagery is provided by the Italian Space Agency (ASI) in the framework of Project (ID 2888/5229) “Spectral and temporal coherence for vessel detection and flood monitoring.” DEM data ? Japan Aerospace Exploration Agency (JAXA).
[deMus.JMAS2018] N. M. de Musso, D. Capolongo, A. Refice, F. P. Lovergine, A. D’Addabbo and L. Pennetta (2018), "Spatial evolution of the December 2013 Metaponto plain (Basilicata, Italy) flood event using multi-source and high-resolution remotely sensed data", Journal of Maps, 14:2, 219-229, DOI: 10.1080/17445647.2018.1454349. Scopus:2-s2.0-85046629764. WOS:000429356000001. ISSN: 1744-5647. IF(2018):1.836, IF(5years):1.724 (Source:WOS).
We present a multi-layer, multi-temporal flood map of the event occurred on December 2013 in Basilicata (southern Italy), documenting the spatial evolution of the inundated areas through time, as well as some ground effects of floodwaters inferred from the imagery. The map, developed within a GIS and consisting of four, 1:20,000 scale, different layers, was prepared using image processing, visual image interpretation and field survey controls. We used two COSMO-SkyMed synthetic aperture radar (SAR) images, acquired during the event, and a Plèiades-1B High-Resolution optical image, acquired at the end of the event. We also used the information derived from the satellite imagery to update some local features of the OpenStreetMap (OSM) geospatial database, and then integrated it within the flood map. A classified multi-temporal dynamic map of inundation and flood effects has been produced in the form of a multi-layer pdf file (Main Map).
COSMO-SkyMed images are courtesy of the Italian Space Agency (ASI). The authors would like to thank Ing. L. Candela, ASI, for the support of the data acquisition. Interferometric synthetic aperture radar processing was performed by Dr. D. O. Nitti of GAP s.r.l. We thank the editor and P. Matgen, F. Yulianto and B. Cattoor for the useful comments which greatly helped in improving the manuscript and the map.
Book Chapters
[Chi.DTA2018] "M. T. Chiaradia, L. Guerriero, R. Nutricato, D. O. Nitti, K. Tijani, A. Morea, F. Ciola, G. Pasquariello,
""La missione Sentinel-1 per il monitoraggio di alluvioni e instabilità del terreno"", in:
""Ricerca, Sviluppo e Formazione in Puglia. I progetti del distretto Tecnologico Aerospaziale: dalla visione strategica ai risultati"",
a cura di G. Acierno, S. Capuzzo, M. Matarrese, A. Zilli. ISBN 978-88-943546-0-7"
Il Distretto Tecnologico Aerospaziale Pugliese ha un ruolo leader sul piano internazionale nel settore del telerilevamento satellitare grazie alla presenza sul territorio regionale di realtà scientifiche e imprenditoriali con competenze complementari pluriennali e ben integrate. Al fine di preservare un elevato livello di competitività in tale settore, GAP, in forte sinergia con i gruppi di Osservazione della Terra (OT) del Dipartimento di Fisica e del CNR-ISSIA di Bari, ha svolto nell’ambito del progetto Apulia Space attività di ricerca e sviluppo. attività di ricerca e sviluppo mirate ad analizzare ed a valorizzare le potenzialità derivanti dall’impiego innovativo di dati SAR (Synthetic Aperture Radar) di nuova generazione. Le recenti missioni satellitari Sentinel-1A e Sentinel-1B dell’ESA (Agenzia Spaziale Europea) hanno infatti introdotto importanti innovazioni non solo tecniche ma anche in termini di data policy che hanno accresciuto notevolmente il potenziale scientifico e commerciale dei servizi di monitoraggio della Terra basati sui dati SAR. La capacità dei sistemi SAR (e dei radar in genere) di operare in qualsiasi condizione meteorologica e in qualsiasi condizione di illuminazione (quindi sia di giorno che di notte) rende questi sistemi particolarmente interessanti, vantaggiosi ed utili in diversi ambiti tra i quali l’importante settore della gestione dei rischi e delle emergenze. Con riferimento a questo ambito, nel presente lavoro si illustrano i risultati riguardanti la sperimentazione di algoritmi innovativi in relazione al monitoraggio di alluvioni ed al monitoraggio della instabilità dei pendii mediante dati SAR acquisiti dalla costellazione Sentinel-1.
Pubblicazione divulgativa dei risultati del progetto Apulia Space (PON-REC 2007–2013, C.N. PON03PE_00067_6)
International Conference Proceedings
[Bov.IGARSS2018] F. Bovenga, A. Refice, A. Belmonte, R. Nutricato, D. O. Nitti, M. T. Chiaradia, S. Valkaniotis, S. Gkioni, C. Kosma, A. Ganas, P. Manunta, E. Darusman, P. Bally, "Cosmo-SkyMed and Sentinel-1 DInSAR processing for ground instability monitoring in Indonesia". Proceedings of the International Geoscience and Remote Sensing Symposium (IGARSS)Volume 2018-July, 31 October 2018, Article number 8518226, Pages 2238-224038th Annual IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018; Valencia; Spain; 22 July 2018 through 27 July 2018. DOI: 10.1109/IGARSS.2018.8518429. Scopus:2-s2.0-85063124540. WOS:000451039800122. ISBN:978-153867150-4. ISSN:2153-6996
Indonesia is periodically affected by severe volcanic eruptions and earthquakes, which are geologically coupled to the convergence of the Australian tectonic plate beneath the Sunda Plate. Multi-temporal SAR interferometry (MTI) can be used to support studying and modelling of terrain movements. This work is aimed at performing an analysis of ground displacements over Indonesian sites through MTI techniques. Two test sites in Sumatra and Java have been selected according to the availability of archived SAR data, GNSS networks, and geological data. Both COSMOSkyMed (CSK) and Senitnel-1 data-sets have been processed through MTI algorithms. The derived displacement maps have been interpreted according to the available geological and geophysical information.
Work supported by ESA project titled "Integrating SAR interferometry and GNSS for studying tectonic processes in Indonesia" (contract 4000114611/15/F/MOS), ESA ITT AO/1-7864/14/F/MOS, Alcantara Study reference 14-P16 "Alcantara Study Enhanced Tectonic Characterization for Indonesia". COSMO-SkyMed data are provided in the framework of the ESA CAT-1 Third Party Mission (TMP) proposal ID 33378.
[Sam.IGARSS2018] S. Samarelli, L. Agrimano, I. Epicoco, M. Cafaro, R. Nutricato, D. O. Nitti, F. Bovenga, "RHETICUS®: a cloud-based geo-information service for ground instabilities detection and monitoring". Proceedings of the International Geoscience and Remote Sensing Symposium (IGARSS)Volume 2018-July, 31 October 2018, Article number 8518226, Pages 2238-224038th Annual IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018; Valencia; Spain; 22 July 2018 through 27 July 2018. DOI: 10.1109/IGARSS.2018.8518226. Scopus:2-s2.0-85063152416. WOS:000451039802096. ISBN:978-153867150-4. ISSN:2153-6996
The Rheticus® cloud-based platform provides continuous monitoring services of the Earth's surface. One of the services provided by Rheticus® is the Displacement Geo-information Service, which offers monthly monitoring of millimetric displacements of the ground surface, landslide areas, the stability of infrastructures, and subsidence due to groundwater withdrawal/entry or from the excavation of mines and tunnels. To provide this information, the Rheticus® platform processes a large amount of Geospatial Big Data. In particular, Rheticus® is capable to process Synthetic Aperture Radar images acquired by the X-band COSMO-SkyMed constellation, as well as satellite Open Data provided by Copernicus Sentinels, and it is capable to integrate local INSPIRE data sources. In this paper, we summarize the main features of the Rheticus® services and we provide examples of the detection and monitoring of geohazard and infrastructure instabilities through Multi-temporal InSAR techniques. Furthermore, we outline the porting activity and the efficient implementation of the most time-consuming algorithmic kernels in the GPGPU environment.
[Chi.OCM2018] M. T. Chiaradia, K. Tijani, A. Morea, R. Nutricato, D. O. Nitti, A. Guerriero, "Exploitation of multi-temporal SAR images devoted to oil spill analysis in the ICWM for MED project", 2018 Ocean Sciences Meeting in Portland, Oregon, 11-16 Feb 2018. https://agu.confex.com/agu/os18/meetingapp.cgi/Paper/310321
The objective of the Integrated Coastal Water Monitoring for Mediterranean Sea project (ICWM for MED), is to demonstrate the benefits of an advanced approach based on the integration of Earth Observation services, Satellite Communication and Navigation solutions together with Terrestrial assets and crowdsourcing features, for the set-up of an improved coastal surveillance and water quality monitoring service in support to current practices on coastal areas for environmental monitoring and reporting. The pilot demonstration has been focused in an area of the central Tyrrhenian Sea, on the western coast of Italy, interesting part of the Naples Gulf and the Salerno Gulf, centred on Punta Campanella. This sea area includes a Protected National Park, which is part of the European network of areas of great environmental importance for the presence of particular habitats and creatures. Therefore, it adds several challenges related to the environmental protection and monitoring, but also opportunities linked to the eco-aware exploitation of its high tourist interest. This work describes the coastal surveillance activities, carried out in the project, aimed at the detection of illegal discharges and forecasting of the oil spills drift. A detailed description of the implemented processing chain is given, including details on the adopted technical solutions and some examples of application of the technique over the area of interest. Particular emphasis is given to the processing of SAR images and their high potential thanks to (i) the acquisition regularity of Sentinel-1 constellation and (ii) the short response and revisit time of COSMO-SkyMed constellation that make these two constellations particularly efficient in the management and monitoring of the maritime traffic.
Work carried out in the framework of the project funded by the European Space Agency within the Integrated Applications Promotion (IAP) ARTES 20 programme (Advanced Research in Telecommunication Systems).
[Bov.EGU2018] F. Bovenga, A. Ganas, A. Refice, A. Belmonte, R. Nutricato, D. O. Nitti, M. T. Chiaradia, S. Valkaniotis, S. Gkioni, C. Kosma, P. Manunta, E. Elizar, D. Darusman, P. Bally, "Investigating ground instability in Indonesia by using multi temporal SAR interferometry", Abstracts proceedings EGU 2018, Vienna, Austria, 08-13 April 2018. Vol. 20, Abstract ID: EGU2018-8488-1, eISSN: 1607-7962. URL: https://meetingorganizer.copernicus.org/EGU2018/EGU2018-8488-1.pdf
Indonesia is periodically affected by severe volcanic eruptions and earthquakes, which are geologically coupled to the convergence of the Australian tectonic plate beneath the Sunda Plate. This work is aimed at performing an analysis of ground displacements over Indonesian sites through Multi-temporal SAR interferometry (MTI). Two test sites, in Sumatra and Java, have been selected according to the following requirements: presence of ground instabilities, possibly related to onshore active faults or volcanoes; good expected interferometric coherence, availability of reliable archived interferometric SAR datasets, availability of ancillary geophysical data. Displacement maps have been obtained by processing COSMO-SkyMed and Sentinel-1 datasets available on the area, through SPINUA algorithm, which performs Persistent Scattering (PS) analysis. The use of datasets coming from two datasets, allows cross-validating final results. The processing of Sentinel-1 data has been more complex w.r.t. that of COSMO-SkyMed data, as standard MTI displacement maps showed strong artifacts, likely due to residual atmospheric contributions and orbital errors. In order to overcome this problem, an alternative processing scheme has been experimented. The tectonic analysis in Indonesia is difficult because the vegetation cover in the area causes lack of PS along and across the faults. Our MTI results provided useful information about the ground stability/instability within the selected test sites. In particular, concerning the tectonic activity in Sumatra, the MTI displacement analysis seems to confirm the inactivity of the Aceh fault segment, as foreseen by geodetic studies. Also, in the Java test site no displacement signal was detected related to possible activity of the faults present in the area. Besides the tectonic activity, ground displacements were also identified basically reflecting local effects. The causes of these displacements were investigated by using ancillary geological data, and in situ inspections. The subsidence phenomena are mainly related to the presence of unconsolidated coastal/alluvial sediments and groundwater pumping. An interesting example concerns a coastal area in Banda Aceh, which was overrun and completely destroyed by the 2004 tsunami. Most subsiding PS targets are positioned on port facilities structures and embankments. Extensive rebuilding and new constructions in the area add weight to the unconsolidated sediments. There is also an extensive presence of seasonally flooded crops and salt production flats. This suggests that the subsidence occurring in the area is probably related to compaction of sediments and/or recent artificial fill. A subsidence has been also revealed in Java over the Yogyakarta urban area. This local displacement is induced by groundwater exploitation and soft sediment compaction, a result of major urban expansion and human activity during the last years. The high resolution of COSMO-SkyMed data allows catching interesting details over urban structures. Finally, interesting localised subsidence rates are observed upon recent (2010) volcanic deposits at the flanks of Mt Merapi in Java, a result of compaction of the soft explosive products (pyroclastic density currents and pumice).
Work supported by ESA project “Integrating SAR interferometry and GNSS for studying tectonic processes in Indonesia” (contract 4000114611/15/F/MOS), under Alcantara Study “Enhanced Tectonic Characterization for Indonesia” (Ref. 14-P16).
[Was.EGU2018] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, and M. T. Chiaradia, "Sentinel-1 data promote a more effective and affordable use of multi-temporal interferometry in slope instability detection and landslide monitoring", Abstracts proceedings EGU 2018, Vienna, Austria, 08-13 April 2018. Vol. 20, Abstract ID: EGU2018-9748-1, eISSN: 1607-7962. URL: https://meetingorganizer.copernicus.org/EGU2018/EGU2018-9748-1.pdf
Landslides and potentially unstable slopes are present in almost every country of the globe. Moreover, the population growth, with increasing impact of humans on the environment and the urbanization of areas susceptible to slope failures implies that landslide hazard mitigation only via traditional engineering stabilization works and in situ monitoring is no longer considered economically feasible. Given the global dimension of the problem of slope instability, a sustainable way towards landslide hazard reduction seems to be via increased exploitation of affordable remote-sensing systems, with focus on early detection, long-term monitoring, and possibly early warning. In particular, satellite-based remote sensing, and especially the synthetic aperture radar (SAR), multi-temporal interferometry (MTI), has great potential thanks to the wide-area coverage of space-borne sensors, day/night image acquisitions and the capability to provide high precision (mm-cm), spatially dense (from hundreds to thousands points per km2) measurements of slow displacements of the ground surface. In this context, Sentinel-1 A/B (S-1) twin satellites of the European Space Agency (ESA), launched in 2014 and 2016, are now providing truly global capacity for innovative, research-oriented and practical MTI applications, such as mapping, characterizing and monitoring of landslides. The regularity of S-1 acquisitions, timeliness of data delivery, increased revisit frequency (days) and the resulting high coherence, as well as the availability of free imagery, facilitate a more effective and innovative use of MTI. The main aim of this work is to compare and assess the potential of MTI based on S-1 data in slope instability investigations with respect to MTI relying on the earlier C-band sensors (ERS and ENVISAT), as well as the high resolution X-band sensors (COSMO-SkyMed, TerraSAR-X). This is done by considering different areas characterized by a wide range of geomorphic, climatic, and vegetation conditions, with case study examples of local to regional scale MTI applications comprising hill slopes in the Apennine Mts. (Italy) and in the European Alps, and unstable slopes in two large open-cast mines of Central Europe. The results show that, by using S-1 data, MTI can now be more effective and affordable in long-term slope/landslide monitoring, early detection of slope instability hazard, and (in some cases) in slope failure early warning.
[Was.IGRS2018] J. Wasowski, F. Bovenga, R. Nutricato, D.O. Nitti, M.T. Chiaradia, "Detecting natural and human-made ground instability hazards via satellite multi-temporal interferometry", 6th International Geo-hazards Research Symposium, March 4-8, 2018, Dresden, Germany.
Conventional investigations and monitoring of areas prone to geological hazards are expensive and limited in terms of spatial and temporal coverage. Therefore, the use of complementary, affordable remote sensing approaches to hazard detection and assessment is desirable. Here we focus on satellite multi-temporal interferometry (MTI), an advanced technique that can facilitate the detection and monitoring hazards such as slope instability and ground subsidence/settlements. MTI provides long-term (years), regular (weekly), precise (mm) measurements of ground displacements over large areas (thousands of km2), combined with high spatial resolution (up to 1-3 m) and a possibility of multi-scale (regional to site-specific) investigations using the same series of radar images. Furthermore, the MTI applications in reconnaissance studies and long-term monitoring are now more effective and affordable thanks to the global coverage (and cost-free imagery) of Sentinel-1 (S-1), a new satellite of the European Space Agency (ESA). The monitoring efforts can benefit from the high acquisition frequency (6-12 days) of S-1 data and be complemented by high resolution MTI relying on the new generation radar sensors (e.g., COSMO-SkyMed, TerraSAR-X). Thereby valuable information is obtained for the spatial and temporal analyses of ground instability hazards. To highlight the potential of MTI, we present few case study examples, one regarding widespread landsliding in a seismically active region of SW China, and the others human-induced ground instabilities in large open-cast coal mines in Central Europe. We also show how high temporal resolution, long-term MTI monitoring can lead to early detection and warning of slope instability hazards.
Sentinel-1, COSMO-SkyMed and TerraSAR-X data provided, respectively, by ESA, Italian Space Agency (ASI) within the COSMO-SkyMed AO Project ID 1820, and German Space Agency (DLR).
[Sam.Esonda2018] "S. Samarelli, R. Nutricato, ""Monitoraggio continuo delle frane con tecnologia radar da satellite"", REMTECH ESONDA EXPO - Salone sul dissesto idrogeologico e sulla manutenzione e gestione del territorio a rischio. Ferrara, 19-21 settembre 2018
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[Dri.MUAS2018] V. Massimi, A. Aiello, D. Drimaco, D. O. Nitti, R. Nutricato, "Pinpointing Failures in Integrated Water and Sewage Networks in Urban Areas". ESA 2nd Mapping Urban Areas from Space Conference, ESA-ESRIN Frascati (Rome, Italy), 30 October 2018.
[Loc.SPIE2018] P. Locorotondo, A. Guerriero, M. T. Chiaradia, R. Nutricato, D. O. Nitti, F. Bovenga, "Preliminary assessment of side-lobe mitigation techniques for proper Coherent Targets selection in MTInSAR applications", SPIE Remote Sensing 2018, Berlin (Germany) 10-13 Sept. 2018.
"Multi-temporal Synthetic Aperture Radar Interferometry (MTInSAR) techniques allow detecting and monitoring millimetric displacements occurring on selected targets exhibiting coherent radar backscattering properties. Because of the bandwidth limitation of Synthetic Aperture Radar images, pulse responses are significantly affected by sidelobes that should be identified and masked out before the selection of coherent targets candidates. In fact, sidelobes often exhibit a coherent backscattering behavior and can be hence erroneously identified as persistent scatterers (PS). The actual large amount of Geospatial Big Data fosters the implementation of automatic tools for sidelobe detection and cancelation.
A number of algorithms have been proposed in the scientific literature for sidelobe reduction in Single-Look-Complex images, ranging from apodization methods to target extraction techniques. In this study we deal in particular with the Spatially Variant Apodization (SVA), a nonlinear filter based on cosine-on-pedestal weighting functions. This approach is attractive because it is able to achieve a total sidelobe cancelation, without degrading the original image resolution, and for its computational efficiency. However, SVA suffers from several drawbacks: (i) it modifies the statistics of speckle-dominated areas, (ii) the amplitude and phase of the original images could be distorted by the SVA filtering, thus compromising the quality of MTInSAR outcomes. Therefore, recent works propose the use of SVA for just identifying and masking out the radar coordinates of the detected side-lobes in the PS candidates position map.
In this work we apply SVA for proper PS selection in COSMO-SkyMed STRIPMAP interferometric dataset, acquired in onshore and offshore environments. In order to highlight both advantages and limitations of this technique, we analyze the performances of SVA approaches in terms of computational efficiency and robustness to focusing artifacts. We test the SVA filtering both in simulation and complex real scenarios, where sidelobes of close strong scatterers are mixed and superimposed upon each other.
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[Sam.SAIE2018] S. Samarelli, R. Nutricato, "Monitoraggio continuo delle infrastrutture con tecnologia radar da satellite", SAIE 2018, Segmento tematico INFRASTRUTTURE E TERRITORIO, Centro Servizi Bologna Fiere. Bologna, 19 OTTOBRE 2018
In multi-temporal applications of synthetic aperture radar (SAR) interferometry, differential phase contributions due to atmospheric inhomogeneities, estimated over sparse points, have to be interpolated and removed from the regular-grid interferograms in order to highlight the phase stability of more image pixels, which then add to the available data to infer useful information about terrain displacements or other phenomena of interest. Interpolation is usually done on the phase data after a phase unwrapping (PU) operation. In a previous work, we considered the alternative interpolation step applied directly to the complex phasor derived from the wrapped phase, thus bypassing the error-prone sparse PU operation. In this article, the performances of the proposed methodology are evaluated over atmospheric phase screen (APS) data estimated from a previous processing through persistent scatterers interferometry (PSI) methods. The original persistent scatterer (PS) population is reduced by thresholding their inter-image coherence values, and then further subsampled randomly in a rectangle inside a detected subsidence bowl. Both the classical and the proposed interpolation procedures are applied to the subsampled APS phase values. The interpolated fields are then removed from the rest of the PS, and the residual phase values are compared in terms of inter-image coherence. Results confirm that interpolating complex phasors, thus avoiding PU, gives results equivalent to the standard procedure in good sampling conditions. Moreover, when point sparsity induces phase aliasing, thus hindering the PU operation, the proposed method allows to better recover phase information over unsampled pixels, improving the final results of the PSI processing.
[Was.IIS2017] "J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti and M. T. Chiaradia, ""High resolution satellite multi temporal interferometry for monitoring infrastructure instability hazards"", Innovative Infrastructure Solutions, (2017) 2: 27. DOI: 10.1007/s41062-017-0077-4. Scopus:2-s2.0-85048586115. WOS:000409249800027. ISSN: 2364-4176 (print version). ISSN: 2364-4184 (electronic version).
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Advanced remote sensing techniques are now capable of delivering more rapidly high quality information that is sufficiently detailed (and cost-effective) for many engineering applications. Here we focus on synthetic aperture radar (SAR), multi-temporal interferometry (MTI). With radar satellites periodically re-visiting the same area, MTI provides information on distance changes between the on-board radar sensor and the targets on the ground (e.g., human-made structures such as buildings, roads and other infrastructure). The detected distance changes are thus interpreted as evidence of ground and/or structure instability. In settings with limited vegetation cover, MTI can deliver very precise (mm resolution), spatially dense information (from hundreds to thousands measurement points/km2) on slow (mm-cm/year) deformations affecting the ground and engineering structures. Radar satellites offer wide-area coverage (thousands km2) and, with the sensors that actively emit electromagnetic radiation and thus can "see" through the clouds, one can obtain deformation measurements even under bad weather conditions. We illustrate the potential of high resolution MTI and explain what this technique can deliver to assist in infrastructure instability hazard assessment. This is done by presenting selected examples of MTI applied to detect and monitor post-construction behavior of engineering structures. The examples are from Italy and include: an earthfill dam, an off-shore vertical breakwater built to protect an oil terminal, city buildings and a highway. We also stress that the current approach to the assessment of instability hazard can be transformed by capitalizing more on the presently underexploited advantage of the MTI technique, i.e., the capability to provide regularly spatially-dense quantitative information for large areas where engineering infrastructure may currently be unaffected by instability, but where the terrain and infrastructure history (e.g., aging) may indicate potential for future failures.
[Nit.SPIEnr2017] D. O. Nitti, A. Morea, R. Nutricato, M. T. Chiaradia, C. La Mantia, L. Agrimano, S. Samarelli, "Automatic identification of ground control points in synthetic aperture radar images", SPIE Newsroom 2017, DOI: 10.1117/2.1201609.006714. ISSN 1818-2259. IF: 0.11 (Source: https://goo.gl/dvVnC2)
This study was carried out within the framework of the 3D IMINT project (PRNM Contract 10444, 30-12-2013). CSK products, under a license from the Italian Space Agency, were used for this project.
[Bov.Catena2017] F. Bovenga, G. Pasquariello, R. Pellicani, A. Refice, G. Spilotro (2017), "Landslide monitoring for risk mitigation by using corner reflector and satellite SAR interferometry: The large landslide of Carlantino (Italy)", Catena, Volume 151, April 2017, Pages 49-62. DOI: 10.1016/j.catena.2016.12.006. Scopus:2-s2.0-85006355973. WOS:000393723300005. ISSN: 0341-8162. eISSN: 1872-6887. IF(2018):3.851, IF(5years):4.149 (Source:WOS).
The use of satellite Synthetic Aperture Radar Interferometry (InSAR) for monitoring ground instability due to landslide events, although advantageous over large spatial scales, still poses challenges related to the recurrently complex kinematics of the phenomena or to the unfavorable settings of the examined areas with respect to steep topography and vegetated land cover. This paper presents results obtained by using Multi-temporal InSAR techniques with high resolution TerraSARX (TSX) data for monitoring the Carlantino landslide, located in the Daunian Subapennine (Apulia region, southern Italy) on a slope overlooking a water reservoir, and subjected to several investigations and consolidation works. The targets detected by using Persistent Scatterer Interferometry (PSI) correspond to urban structures or peri-urban walls and guard rails, while the landslide body is almost completely devoid of stable targets, due to the widespread vegetation and variable land cover. To allow stability monitoring, a network of six Corner Reflectors (CR) was designed and deployed over the landslide test site. The TSX images were analyzed by using both the PSI processing and a procedure, based on the double difference analysis of InSAR phase values on the CR pixels. Despite residual noise and the loss of 2 CRs due to vandalism, the processing allowed verifying the stability of the upper and central part of the landslide body, and relating indirectly the movements at the toe of the landslide to the water level fluctuations of the reservoir. Finally, this experiment suggests some recommendations and guidelines in planning CR deployment in complex landslide sites.
Work supported by the Italian Ministry of Research in the framework of PRIN 2008 research (2008EW9WAM) grant "Advanced technologies in the assessment and mitigation of the landslide risk: precursors detection, previsional models and thematic mapping". Terra SAR-X data are provided by DLR under TerraSAR-X General AO Project ID MTH0432. PS map on Carlantino from TSX data was obtained by GAP srl in the framework of the Puglia Region project "FRANE PUGLIA - Rilevamento di deformazioni al suolo con tecniche satellitari avanzate". Authors thank Ing. Davide Oscar Nitti from GAP srl for supporting InSAR processing, and Ing. Pino D'Amelio for supporting the deployment activity. Finally, authors thank the anonymous reviewers for the constructive suggestions.
Book Chapters
[Was.WLF4] "Wasowski J., Bovenga F., Nutricato R., Nitti D.O., Chiaradia M.T. (2017) ""Detection and Monitoring of Slow Landslides Using Sentinel-1 Multi-temporal Interferometry Products"". In: Mikos M., Tiwari B., Yin Y., Sassa K. (eds) Advancing Culture of Living with Landslides. WLF 2017. Springer, Cham. DOI: 10.1007/978-3-319-53498-5_28. WOS:000438665000028 Print ISBN: 978-3-319-53497-8. Online ISBN: 978-3-319-53498-5
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Landslide investigations can now benefit from high quality information obtainable using multi-temporal interferometry (MTI) techniques (e.g., PSInSAR, SBAS) and images acquired by satellite synthetic aperture radars (SAR). MTI is only little affected by bad weather and can provide long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), with the possibility of exploiting the same series of radar images for regional to slope-scale investigations. Spatially dense measurements can be obtained (from hundreds to thousands data per km2). Furthermore, by offering regular global-scale coverage, improved temporal resolution (from 12 to 6 days) and free imagery, the new radar satellite mission Sentinel-1 of the European Space Agency (ESA) can now guarantee wider and more efficient application of MTI to landslide investigations. In this work we demonstrate for the first time the excellent potential of MTI based on Sentinel-1 for the detection and monitoring of slope instabilities affecting small hilltop towns in the Apennine Mountains of southern Italy. The is done by comparing the MTI results based on Sentinel-1 images with those based on ENVISAT data (ESA satellite retired few years ago). The comparison shows that by using Sentinel-1 imagery a few times higher density of radar targets (measurement points) can be obtained. Thanks to this and more frequent measurement capability of Sentinel-1, landslide detection and monitoring can be more effective.
Work supported by the Apulia Space project (PON&REC 2007-2013, Cod: PON03PE_00067_6). ENVISAT and Sentinel-1 imagery provided by the European Space Agency (ESA).
International Conference Proceedings
[Bov.SPIE2017] Bovenga F., Refice A., Belmonte A., Nutricato R., Nitti D.O., Chiaradia M.T., Valkaniotis S., Gkioni S., Kosma C., Ganas A., Manunta P., Elizar E., Darusman D., Bally P.,"Investigating ground instabilities in Indonesia through SAR interferometry", Proc. SPIE 10426, Active and Passive Microwave Remote Sensing for Environmental Monitoring, 1042602 (3 October 2017); doi: 10.1117/12.2277838. Scopus: 2-s2.0-85041279038. WOS:000425527900001. ISSN: 0277-786X. ISSN: 1996-756X (electronic). ISBN: 9781510613164. ISBN: 9781510613171 (electronic).
Indonesia is periodically affected by severe volcanic eruptions and earthquakes, which are geologically coupled to the convergence of the Australian tectonic plate beneath the Sunda Plate. Multi-Temporal SAR interferometry (MTI) can be used to support studying and modelling of terrain movements. This work is aimed at performing an analysis of ground displacements over Indonesian sites through MTI techniques. Test sites have been selected according to the availability of archived SAR data, GNSS networks, and geological data. A stack of COSMO-SkyMed data, acquired in stripmap mode between 2011 and 2015, has been selected over the Banda Aceh region in Sumatra island. Geological maps of the test sites are available, and several GNSS stations from the Continuously Operating Reference Stations Indonesian network are found in the area of interest. Both the SPINUA and the StaMPS MTI algorithms have been used for processing the data, and deriving displacement maps. The ground deformations detected on the area are interpreted according to the available geological and geophysical information. The MTI results seem to confirm the inactivity of the Aceh fault segment, while the lack of coherent targets hinders reliable displacement measurements along the Seulineum segment. MTI data additionally allowed to identify local, non-Tectonic ground instabilities: several areas are affected by subsidence due to unconsolidated coastal and alluvial sediments, deserving more investigations by local authorities. Finally, MTI results could be useful to integrate and update data from the existing GPS network.
Work supported by ESA project titled “Integrating SAR interferometry and GNSS for studying tectonic processes in Indonesia” (contract 4000114611/15/F/MOS), ESA ITT AO/1-7864/14/F/MOS, Alcantara Study reference 14-P16 “Alcantara Study Enhanced Tectonic Characterization for Indonesia”. COSMO-SkyMed data are provided in the framework of the ESA CAT-1 Third Party Mission (TMP) proposal ID 33378.
[Sam.Bids2017] S. Samarelli, V. Massimi, L. Agrimano, D. Drimaco, R. Nutricato, D. O. Nitti, M. T. Chiaradia, "RHETICUS®: A CLOUD-BASED GEO-INFORMATION SERVICE FOR GROUND INSTABILITIES DETECTION AND MONITORING BASED ON FUSION OF EARTH OBSERVATION AND INSPIRE DATA". In: P. Soille and P.G. Marchetti (Eds.), Proceedings of the 2017 conference on Big Data from Space. BIDS' 2017, EUR 28783 EN, Publications Office of the European Union, Luxembourg, 2017, ISBN 978-92-79-73527-1, ISSN 1831-9424, doi:10.2760/383579, JRC108361
The Rheticus® cloud-based platform provides continuous monitoring services of the Earth's surface. One of the services provided by Rheticus® is the Displacement Geoinformation Service, which offers monthly monitoring of millimetric displacements of the ground surface, landslide areas, the stability of infrastructures, and subsidence due to groundwater withdrawal/entry or from the excavation of mines and tunnels. To provide this information, the Rheticus® platform processes a large amount of Geospatial BigData. In particular, Rheticus® processes satellite Open Data provided by Copernicus Sentinels and it is capable to integrate local INSPIRE data sources. Rheticus® can automatically process the datasets that are compliant to the INSPIRE data specifications. We outline the automatic generation process of displacement maps and we provide examples of the detection and monitoring of geohazard and infrastructure instabilities.
Rheticus® is a registered trademark of Planetek Italia srl. Research activities carried out in the framework of the FAST4MAP project (“Fast & Advanced SAR Techniques for Monitoring & Alerting Processes”) and co-funded by the Italian Space Agency (Contract n. 2015-020-R.0). Sentinel-1A products provided by ESA. Computational work partly executed on the IT resources made available by ReCaS grid and cloud infrastructure, a project financed by the MIUR (PON R&C 2007-2013).
National Conference Proceedings
[Sam.ENEA2017] S. Samarelli, V. Massimi, C. La Mantia, L. Agrimano, D.O. Nitti, R. Nutricato, M. T. Chiaradia, "Monitoraggio continuo del territorio e delle infrastrutture con dati satellitari SAR: il servizio Rheticus® Displacement", 11mo Workshop Tematico AIT-ENEA di Telerilevamento - Osservazione della Terra: Georisorse, Risorse Produttive, Geopolitica, Calamità Naturali e Beni Culturali, 27-28 Giugno 2017, Bologna Italia. URL: http://www.enea.it/it/seguici/events/ait_27-28giu17/PlanetekMassimi_AITENEA2017.pdf
Il monitoraggio delle infrastrutture e del territorio è una attività fondamentale per garantire la incolumità delle persone, la tutela dell’ambiente e la salvaguardia degli asset in tutte le fasi del ciclo di vita delle infrastrutture: progettazione, realizzazione, gestione. L’utilizzo delle tecniche topografiche tradizionali (Stazione Totale, reti GNSS etc) per un monitoraggio periodico su aree vaste o remote, richiede generalmente notevoli risorse economiche e di tempo e risulta pertanto una soluzione di difficile applicazione su piccola/media scala. Al contrario, l’utilizzo delle tecnologie di monitoraggio satellitare sfruttando immagini o ottiche e radar permette di superare questi limiti e di disporre di informazioni frequenti, precise e sostanzialmente accessibili, grazie ad una ormai ampia disponibilità di informazioni territoriali, anche in modalità open data attraverso il programma dell’Unione Europea Copernicus. Le immagini acquisite dai satelliti Sentinel sono alla base dei servizi di monitoraggio erogati dalla piattaforma su cloud Rheticus® (www.rheticus.eu). I servizi spaziano dal monitoraggio della stabilità delle infrastrutture (edifici, strade, reti idriche, dighe, ecc.) al monitoraggio della stabilità dei versanti e della subsidenza attraverso il servizio Rheticus® Displacement, alla qualità delle acque marino costiere attraverso il servizio Rheticus® Marine, agli incendi boschivi, ai cambiamenti antropici del territorio.
Rheticus® è un marchio registrato di Planetek Italia srl. Le attività di ricerca sono state finanziate nell’ambito del progetto FAST4MAP (ASI Contract n. 2015-020-R.0). I dati Sentinel-1 sono forniti dall’Agenzia Spaziale Europea. Le immagini CSK® sono fornite in licenza d’uso dall’Agenzia Spaziale Italiana.
Conference Abstracts
[Arg.EGU2017] I. Argentiero, R. Pellicani, G. Spilotro, A. Parisi, F. Bovenga, G. Pasquariello, A. Refice, R. Nutricato, D. O. Nitti, and M. T. Chiaradia, "Enhanced SAR data processing for land instability forecast", Abstracts proceedings EGU 2018, Vienna, Austria, 23-28 April 2017. Vol. 19, Abstract ID: EGU2017-17674, eISSN: 1607-7962. URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-17674.pdf
Monitoring represents the main tool for carrying out evaluation procedures and criteria for spatial and temporal landslide forecast. The forecast of landslide behaviour depends on the possibility to identify either evidences of activity (displacement, velocity, volume of unstable mass, direction of displacement, and their temporal variation) or triggering parameters (rainfalls). Generally, traditional geotechnical landslide monitoring technologies permit to define, if correctly positioned and with adequate accuracy, the critical value of displacement and/or acceleration into landslide body. In most cases, they do not allow real time warning signs to be generated, due to environmental induced errors, and the information is related to few points on unstable area. Remote-sensing monitoring instruments are capable of inspecting an unstable slope with high spatial and temporal frequency, but allow solely measurements of superficial displacements and deformations. Among these latest technologies, the satellite Persistent Scatterer SAR Interferometry (PSInSAR) is very useful to investigate the unstable area both in terms of space and time. Indeed, this technique allows to analyse wide areas, individuate critical unstable areas, not identifiable by means detailed in situ surveys, and study the phenomenon evolution in a long time-scale. Although this technique usually adopts, as first approximation, a linear model to describe the displacement of the detected targets, also non-linear models can be used. However, the satellite revisit time, which defines the time sampling of the detected displacement signal, limits the maximum measurable velocity and acceleration. This makes it difficult to assess in the short time any acceleration indicating a loss of equilibrium and, therefore, a probable reactivation of the landslide. The recent Sentinel-1 mission from the European Space Agency (ESA), provides a spatial resolution comparable to the previous ESA missions, but a nominal revisit time reduced to 6 days. By offering regular global-scale coverage, better temporal resolution and freely available imagery, Sentinel-1 improves the performance of PSInSAR for ground displacement investigations. In particular, the short revisit time allows a better time series analysis by improving the temporal sampling and the chances to catch pre-failure signals characterised by high rate and non-linear behaviour signals. Moreover, it allows collecting large data stacks in a short time period, thus improving the PSInSAR performance in emergency (post-event) scenarios. In the present work, we propose to match satellite data with numerical analysis techniques appropriate to evidence unsteady kinematics and, thanks to the high resolution of satellite data and improved temporal sampling, to detect early stages of land instability phenomena. The test area is situated in a small town in the Southern Apennine, Basilicata region, affected by old and new huge landslides, now close to a lived outskirt.
[Chi.AGU2017] M. T. Chiaradia, S. Samarelli, V. Massimi, R. Nutricato, D. O. Nitti, A. Morea, K. Tijani, "Rheticus: a cloud-based Geo-Information Service for the Detection and Monitoring of Geohazards and Infrastructural Instabilities", AGU Fall Meeting 2017, Abstract ID:155327, Poster Presentation G23A-0878, New Orleans, USA, 11-15 December 2017. URL (abstract): https://agu.confex.com/agu/fm17/meetingapp.cgi/Paper/225023 URL (Poster): https://agu.confex.com/agu/fm17/mediafile/Handout/Paper225023/AGU2017_poster_Rheticus.pdf
Geospatial information is today essential for organizations and professionals working in several industries. More and more, huge information is collected from multiple data sources and is freely available to anyone as open data. Rheticus® is an innovative cloud-based data and services hub able to deliver Earth Observation added-value products through automatic complex processes and, if appropriate, a minimum interaction with human operators. This target is achieved by means of programmable components working as different software layers in a modern enterprise system which relies on SOA (Service-Oriented-Architecture) model. Due to its spread architecture, where every functionality is defined and encapsulated in a standalone component, Rheticus is potentially highly scalable and distributable allowing different configurations depending on the user needs. This approach makes the system very flexible with respect to the services implementation, ensuring the ability to rethink and redesign the whole process with little effort. In this work, we outline the overall cloud-based platform and focus on the "Rheticus Displacement" service, aimed at providing accurate information to monitor movements occurring across landslide features or structural instabilities that could affect buildings or infrastructures. Using Sentinel-1 (S1) open data images and Multi-Temporal SAR Interferometry techniques (MTInSAR), the service is complementary to traditional survey methods, providing a long-term solution to slope instability monitoring. Rheticus automatically browses and accesses (on a weekly basis) the products of the rolling archive of ESA S1 Scientific Data Hub. S1 data are then processed by SPINUA (Stable Point Interferometry even in Unurbanized Areas), a robust MTInSAR algorithm, which is responsible of producing displacement maps immediately usable to measure movements of point and distributed scatterers, with sub-centimetric precision. We outline the automatic generation process of displacement maps and we provide examples of the detection and monitoring of geohazard and infrastructure instabilities.
Rheticus® is a registered trademark of Planetek Italia srl. Study carried out in the framework of the FAST4MAP project (ASI Contract n. 2015-020-R.0). Sentinel-1A products provided by ESA.
[Ref.3intrisk2017] A. Refice, F. Bovenga, G. Pasquariello, R. Nutricato, D. O. Nitti, M. T. Chiaradia, I. Argentiero, R. Pellicani, G. Spilotro, A. Parisi, "Analysis of interferometric SAR data for Stigliano landslide monitoring: potentials and issues", Abstract - III International Workshop "Methods and technologies for environmental monitoring and modelling: emerging signals, risk perception and management", 14-16 Sept. 2017. URL: http://hydrogeology.ba.irpi.cnr.it/wp-content/uploads/2017/09/Workshop-Brochure-Matera.pdf
Monitoring represents the main tool for carrying out evaluation procedures and criteria for spatial and temporal landslide forecast. The forecast of landslide behaviour depends on the possibility to identify either evidences of activity (displacement, velocity, volume of unstable mass, direction of displacement, and their temporal variation) or triggering parameters (rainfalls). Generally, traditional geotechnical landslide monitoring technologies do not allow real time warning signs to be generated, due to environmental induced errors, and the information is related to few points on unstable area. Remotesensing monitoring instruments are capable of inspecting an unstable slope with high spatial and temporal frequency, but allow solely measurements of superficial displacements and deformations. Among these latest technologies, the satellite Persistent Scatterer SAR Interferometry (PSInSAR) is very useful to investigate the unstable area both in terms of space and time. Indeed, this technique allows to analyse wide areas, individuate critical unstable areas, not identifiable by means detailed in situ surveys, and study the phenomenon evolution in a long time-scale. Although this technique usually adopts, as first approximation, a linear model to describe the displacement of the detected targets, also non-linear models can be used. However, the satellite revisit time, which defines the time sampling of the detected displacement signal, limits the maximum measurable velocity and acceleration. This makes it difficult to assess in the short time any acceleration indicating a loss of equilibrium and, therefore, a probable reactivation of the landslide. The recent Sentinel-1 mission from the European Space Agency (ESA), provides a spatial resolution comparable to the previous ESA missions, but a nominal revisit time reduced to 6 days. By offering regular global-scale coverage, better temporal resolution and freely available imagery, Sentinel-1 improves the performance of PSInSAR for ground displacement investigations. In particular, the short revisit time allows a better time series analysis by improving the temporal sampling and the chances to catch pre-failure signals characterised by high rate and non-linear behaviour signals. Moreover, it allows collecting large data stacks in a short time period, thus improving the PSInSAR performance in emergency (post-event) scenarios. We presents a study focused on Stiglianto, a small town in the Southern Apennine, Basilicata region, affected by old and new huge landslides, now close to a lived outskirt. The integration of ground monitoring and Sentinel-1 PSInSAR processing has been performed. Comparisons of laser-monitored locations on the landslide perimeter with closest PS point time series shows fair agreement, hinting to possible accelerations or decelerations of different parts of the landslide. Moreover, we attempted time series analysis to discover early warnings of damaging displacements. Although several issues have to be solved and deserve more investigations, Sentinel-1 data look promising in this direction.
[Ref.EGU2017] A. Refice, K. Tijani, F. P. Lovergine, A. D’Addabbo, R. Nutricato, A. Morea, D. Capolongo, L. Stamatopoulos , F. Bovenga, M.T. Chiaradia, "Monitoring flood extent and area through multi-sensor, multi-temporal remote sensing: the Strymonas (Greece) river flood", Abstracts proceedings EGU 2018, Vienna, Austria, 23-28 April 2017. Vol. 19, Abstract ID: EGU2017-7877, eISSN: 1607-7962. URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-7877-1.pdf
Satellite monitoring of flood events at high spatial and temporal resolution is considered a difficult problem, mainly due to the lack of data with sufficient acquisition frequency and timeliness. The problem is worsened by the typically cloudy weather conditions associated to floods, which obstacle the propagation of e.m. waves in the optical spectral range, forbidding acquisitions by optical sensors. This problem is not present for longer wavelengths, so that radar imaging sensors are recognized as viable solutions for long-term flood monitoring. In selected cases, however, weather conditions may remain clear for sufficient amounts of time, enabling monitoring of the evolution of flood events through long time series of satellite images, both optical and radar. In this contribution, we present a case study of long-term integrated monitoring of a flood event which affected part of the Strymonas river basin, a transboundary river with source in Bulgaria, which flows then through Greece up to the Aegean Sea. The event, which affected the floodplain close to the river mouth, started at the beginning of April 2015, due to heavy rain, and lasted for several months, with some water pools still present at the beginning of September. Due to the arid climate characterizing the area, weather conditions were cloud-free for most of the period covering the event. We collected one high-resolution, X-band, COSMO-SkyMed, 5 C-band, Sentinel-1 SAR images, and 11 optical Landsat-8 images of the area. SAR images were calibrated, speckle-filtered and precisely geocoded; optical images were radiometrically corrected to obtain ground reflectance values from which NDVI maps were derived. The images were then thresholded to obtain binary flood maps for each day. Threshold values for microwave and optical data were calibrated by comparing one SAR and one optical image acquired on the same date. Results allow to draw a multi-temporal map of the flood evolution with high temporal resolution. The extension of flooded area can also be tracked in time, allowing to envisage testing of evapotranspiration/absoption models.
Work supported by the Apulia Space project (PON&REC 2007-2013, Cod: PON03PE_00067_6). Sentinel-1 imagery provided by the European Space Agency (ESA). COSMO-SkyMed imagery provided by ASI in the framework of Project (ID 2888/5229) “Spectral and temporal coherence for vessel detection and flood monitoring”
[Was.AGU2017] "J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, M. T. Chiaradia, K. Tijani, A. Morea, ""Forecasting slope failures from space-based synthetic aperture radar (SAR) measurements"" (Invited), AGU Fall Meeting 2017, NH42A-01, New Orleans, USA, 11-15 December 2017. URL (abstract): https://agu.confex.com/agu/fm17/meetingapp.cgi/Paper/228195
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New space-borne radar sensors enable multi-scale monitoring of potentially unstable slopes thanks to wide-area coverage (tens of thousands km2), regular long-term image acquisition schedule with increasing re-visit frequency (weekly to daily), and high measurement precision (mm). In particular, the recent radar satellite missions e.g., COSMO-SkyMed (CSK), Sentinel-1 (S-1) and improved multi-temporal interferometry (MTI) processing techniques allow timely delivery of information on slow ground surface displacements. Here we use two case study examples to show that it is possible to capture pre-failure slope strains through long-term MTI-based monitoring. The first case is a retrospective investigation of a huge ~500ML m3 landslide, which occurred in Sept. 2016 in a large, active open-cast coal mine in central Europe. We processed over 100 S-1 images acquired since Fall 2014. The MTI results showed that the slope that failed had been unstable at least since 2014. Importantly, we detected consistent displacement trends and trend changes, which can be used for slope failure forecasting. Specifically, we documented significant acceleration in slope surface displacement in the two months preceding the catastrophic failure. The second case of retrospectively captured pre-failure slope strains regards our earlier study of a small ~50 m long landslide, which occurred on Jan. 2014 and caused the derailment of a train on the railway line connecting NW Italy to France. We processed 56 CSK images acquired from Fall 2008 to Spring 2014. The MTI results revealed pre-failure displacements of the engineering structures on the slope subsequently affected by the 2014 slide. The analysis of the MTI time series further showed that the displacements had been occurring since 2009. This information could have been used to forewarn the railway authority about the slope instability hazard. The above examples indicate that more frequent and consistent image acquisitions by the new radar satellites represent the key improvement for MTI-based slope monitoring. The forecasting of potential slope failures from space is now more feasible.
We thank European (ESA) and Italian (ASI) space agencies for S-1 and CSK® Products. We also acknowledge the IT resources made available by ReCaS, a project financed by the MIUR.
[Was.EGU2017] J. Wasowski, F. Bovenga, D. O. Nitti, K. Tijani, A. Morea, R. Nutricato, M. T. Chiaradia, "Capturing pre-failure signs of slope instability using multi-temporal interferometry and Sentinel-1 data", Abstracts proceedings EGU 2018, Vienna, Austria, 23-28 April 2017. Vol. 19, Abstract ID: EGU2017-9123, eISSN: 1607-7962. URL: http://meetingorganizer.copernicus.org/EGU2017/EGU2017-9123.pdf
The shorter repeat cycle (6 days since October 2016) and regularity of acquisitions of Sentinel-1A/B with respect to earlier European Space Agency (ESA) satellites with C-band sensors (ERS1/2, ENVISAT) represent the key advantages for the research-oriented and practical applications of multi-temporal interferometry (MTI). The applicability of the Interferometric Wide Swath acquisition mode of Sentinel-1 (images covering a 250 km swath on the ground) to regional scale slope instability detection through MTI has already been demonstrated, e.g., via studies of landslide-prone areas in Italy. Here we focus on the potential of Sentinel-1 data for local (site-specific), MTI-based monitoring and capturing pre-failure signs of slope instability, by exploiting the Persistent and Distributed Scatterers processing capability of the SPINUA algorithm. In particular, we present an example of a retrospective study of a large (over 2 km long) landslide, which took place in 2016 in an active open-cast coal mine in central Europe. This seemingly sudden failure caused destruction of the mining equipment, blocked the mining operations thereby resulting in significant economic losses. For the study, we exploited over 60 Sentinel-1A/B images acquired since November 2014. The MTI results furnished a valuable overview of the ground instability/stability conditions within and around the active mine, even though considerable spatial gaps in information were encountered due to surface disturbance by mining operations. Significantly, the ground surface displacement time series revealed that the 2016 slope failure was preceded by very slow (generally 1-3 cm/yr) creep-like deformations, already present in 2014. The MTI results also indicated that the slope experienced a phase of accelerated movement several weeks prior to the landslide event. Furthermore, the spatio-temporal analysis of interferometric coherence changes in the unstable area (mapped on Sentinel-2 Bottom Of Atmosphere reflectance images processed by using the ESA Sen2Cor processor), indicated a sharp coherence loss in the last few weeks before the slope collapse. The availability of more frequent measurements represents a key improvement for MTI-based ground surface displacement monitoring and this will better support research on slope destabilization processes over time and, ultimately, on slope failure forecasting.
[Was.SPIE2017] J. Wasowski, F. Bovenga, D. O. Nitti, K. Tijani, A. Morea, R. Nutricato and M. T. Chiaradia, "Using multi-temporal interferometry and Sentinel-1 data to monitor ground instability hazards related to open-cast mining operations", Technical Summaries of SPIE Remote Sensing 2017, 11 - 14 September 2017, Warsaw, Poland. Abstract ID: 10426-2. URL: https://spie.org/Documents/ConferencesExhibitions/ERS-ESD17%20Abstracts%20lr.pdf
Surface mining represents the predominant mineral and coal exploitation method in Europe and worldwide. Different mining methods can be involved, but most often: open-cast (open-pit) mining; terrace mining; contour strip mining; quarrying. Although surface mining is considered safer than underground mining, ground instability hazards represent an ever-present concern and important problem limiting the mining operations (e.g., slope instability in high wall open-cast mines and quarries). However, given the often large extent of areas affected by surface mining and life span of mines (tens of years), long-term monitoring via traditional in-situ methods is typically impractical (economically and technically). Here we focus on the use of an advanced multi-temporal interferomery (MTI) and Sentinel-1 imagery for mapping and monitoring of ground instabilities in open-cast mines and adjacent areas. Open-cast mines represent a good target for MTI, because they are i) often very large (from few to tens of km2); ii) free of or covered by sparse vegetation; iii) require long-term regular monitoring, which can now rely on free of charge Sentinel-1 data from the European Space Agency. However, a cursory review of the recent literature (international journals) suggests that in comparison to applications to underground mines, MTI has been relatively little exploited to investigate ground instabilities related to surface mining. One reason for this is that some portions of open-cast mines can lack measurable radar targets due to rapid changes of ground surface caused by intense mining operations (e.g., overburden stripping, waste material damping). We argue that this limitation can now be mitigated by the higher frequency and regularity of acquisitions provided by Sentinel-1 (nominally every 6 days since October 2016). To illustrate the potential of MTI for detecting and monitoring ground instabilities induced by surface mining, we present case study example of the Belchatow mine (Poland), one of the largest brown coal open-cast operations in Europe (about 12 km long and 3 km wide). The Belchatow open-cast mine reaches the depth of 310 m and has been affected by a number of slope failures in the last few decades. The failures disrupted the mining operations, destroyed in part the mining machinery and resulted in high economic losses. In this study we assess the recent and current stability conditions in the mine area by exploiting several tens of medium resolution (~20 m) images acquired by Sentinel-1 since October 2014. Despite the local lack of information (areas affected by intensive surface disturbance due to ongoing mining operations), the MTI results provided a valuable synoptic overview of the ground instability/stability condition within and outside the active mine. Although it is not simple to provide short-term forewarning of the impeding slope failure on the basis of the surface displacement time series alone, our experience indicate that long-term, high frequency MTI measurements offer the following benefits: i) better anticipation of risk of failure over large areas and more rational design of ground-based monitoring networks; ii) better planning for maintenance and management of open-cast mines.
[Bel.Fringe2017] Belmonte A., Refice A., Bovenga F., Pasquariello G., Nutricato R., "Improving Atmospheric Phase Screen (APS) Removal in Multi-temporal Radar Interferometry through Complex Interpolation". In: Abstract Book of the Fringe 2017 Workshop - the 10th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR", 5-9 June 2017, Helsinki, Finland. URL: http://fringe.esa.int/files/Fringe2017_Abstract_Book_FINAL.pdf
Many applications of synthetic aperture radar differential interferometry (DInSAR) lead to a set of sparse phase measurements, e.g. in the processing of long multitemporal stacks of SAR differential interferograms through persistent scatterers interferometry (PSI) techniques. Often, sparse phase data have to be unwrapped, and then interpolated on a regular grid to be useful for subsequent processing steps. This step is necessary for instance in the reconstruction of the so-called APS (Atmospheric Phase Screen). Atmospheric artifacts superimposed on DInSAR measurements have the potential of hindering the accurate estimation of deformation signals. Indeed, sometimes the spatial frequencies of the atmospheric phase contributions can overlap those of deformation signals, so that such artifacts can be misinterpreted as deformation features. For the phase unwrapping stage, the solutions are directly dependent on the PS network density; moreover, phase aliasing, which appears when the signal sampling does not satisfy the Nyquist condition, especially in presence of noise, increases when passing from regular-grid to sparse data. This is because the phase sampling conditions get usually worse. An improvement of the APS estimation step has been proposed, by investigating from the empirical point of view an alternative procedure, which involves an interpolation of the complex field derived from the sparse phase measurements. Unlike traditional approaches, the proposed method allows to bypass the PU step and obtain a regular-grid complex field, from which a wrapped phase field can be extracted. Under general conditions, this smooth phase field can be shown to be a good approximation of the original phase without noise. Moreover, the interpolated, wrapped phase field can be fed to state of the art, regular grid PU algorithms, to obtain a smoother absolute phase field. The performances of this empirical approach are evaluated here over a real dataset, that is composed by 30 ascending SAR X-band COSMO-SkyMed images. The images cover the urban area and outskirts of the capital of Haiti, Port-au-Prince. The accuracy of the reconstructed phase fields is analyzed by the local value of the final inter-image phase coherence (?int), a quality figure related to the residual phase noise after subtraction of all modeled contributions. Its values are taken on points (PS) not used in the interpolation, using different spatial densities and random subsampling patterns in a test area characterized by a strong subsidence bowl. The obtained results may be applied into a broader context than the one specific to the PSI technique, considering the few assumptions on the initial phase field, i.e. its smoothness and good sampling conditions.
[Bov.Fringe2017] Bovenga F., Refice A., Belmonte A., Nutricato Raffaele (2), Nitti D. O., Chiaradia M. T., Ganas A., Manunta P., Elizar E., Bally P., "Investigating ground instabilities in Sumatra and Java islands by integrating SAR Interferometry and GNSS".In: Abstract Book of the Fringe 2017 Workshop - the 10th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR", 5-9 June 2017, Helsinki, Finland. URL: http://fringe.esa.int/files/Fringe2017_Abstract_Book_FINAL.pdf
Indonesia is periodically affected by severe volcanic eruptions and earthquakes, which are geologically coupled to the convergence of the Australian tectonic plate beneath the Sunda Plate. SAR interferometry (InSAR) can be used to support studying and modeling of terrain movements such as tectonic motions associated with faults. Multi-temporal InSAR (MTI) techniques provide both mean displacement maps and displacement time series over selected, stable objects on the Earth surface. Nowadays, historical SAR data acquired in different bands and from several satellite missions are available, and the launch of Sentinel-1A/B guarantees data for the next future. The study of tectonic phenomena requires large-scale spatial analysis that poses challenges in MTI processing. A reliable modeling needs additional information coming e.g. from geodetic data, such as those provided by GNSS networks. This work is aimed at performing an analysis of ground displacements over Indonesian sites through MTI techniques. Test sites have been selected according to the availability of archived SAR data, GNSS networks, and geological data. Based on the existence of i) onshore active faults, ii) undergoing deformation as from GPS data, iii) foreseen good interferometric coherence, iv) availability of SAR imagery, two stacks of COSMO-SkyMed data, both acquired in stripmap mode between 2011 and 2015 , have been selected, one on the capital Banda Aceh (descending geometry, mean incident angle of 32.2°) and a second one on the city of Yogyakarta (ascending geometry, mean incident angle of 29.3°). Geological maps of the Banda Aceh and Yogyakarta test sites are available, and several GNSS stations from the Continuously Operating Reference Stations (CORS) Indonesian network are found to be located in the areas of interest: 24 in Banda Aceh and 36 in Yogyakarta. For each station, horizontal velocity values and displacement time series are available. Sentinel-1 data are also available, even though their number is quite limited (between 20 and 30) because of the reduced acquisition frequency. Nevertheless, Sentinel-1 acquisition geometries on the two test sites are complementary to those of the COSMO-SkyMed data, thus allowing in principle the combination of InSAR-based displacement maps derived from different viewing geometries. Both the SPINUA and the StaMPS algorithms have been used to process the data. The former is well suited for scarcely urbanized areas and high resolution local scale analysis, while the latter has been proven effective for studying both volcanic deformations and fault slips. This processing strategy also allows us to cross-validate MTI results. Integration of Java and Aceh province observations from SAR satellites with ground-based GNSS observations has been attempted, with the aim of producing a uniform product, improving on the existing, low-resolution global strain rate map (http://gsrm.unavco.org/) derived from GNSS alone. The work describes the MTI processing adopted, and the procedure developed to integrate the MTI deformation maps with the records derived from GNSS observations. The ground deformations undergoing on the area of interest are then modeled according to these integrated products.
Work supported by ESA project titled “Integrating SAR interferometry and GNSS for studying tectonic processes in Indonesia” (contract 4000114611/15/F/MOS), ESA ITT AO/1-7864/14/F/MOS, Alcantara Study reference 14-P16 -163- “Alcantara Study Enhanced Tectonic Characterization for Indonesia”. COSMO-SkyMed data are provided in the framework of the ESA CAT-1 Third Party Mission (TMP) proposal ID 33378.
[Bov.Fringe2017b] Bovenga F., Refice A., Belmonte A., Pasquariello G., Nutricato R., Nitti D. O., "Performance analysis of recent SAR satellite missions for multi-temporal SAR interferometry.". In: Abstract Book of the Fringe 2017 Workshop - the 10th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR", 5-9 June 2017, Helsinki, Finland. URL: http://fringe.esa.int/files/Fringe2017_Abstract_Book_FINAL.pdf
Multi-temporal InSAR (MTI) applications pose challenges related to the availability of coherent scattering from the ground surface, the complexity of the ground deformations, presence of atmospheric artifacts, and visibility problems related to the ground elevation. Nowadays, several satellite missions are available, providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit times. High-resolution X-Band SAR sensors, such as the COSMO-SkyMed constellation, acquire data with spatial resolution reaching metric values, and revisit time up to a few days, leading to an increase in the density of usable targets, as well as to an improved detection of non linear movements. Medium resolution C-band SAR data have been thoroughly exploited in the last two decades, thanks to the ERS-1/2 and ENVISAT-ASAR missions, and Radarsat-1/2. A new interesting opportunity is provided by the Sentinel-1 mission, which has a spatial resolution comparable to previous ESA C-band missions, and a revisit time reduced to 12 and 6 days, by considering, respectively, one or two satellites. It is envisioned that, by offering regular, global scale coverage, improved temporal resolution and freely available imagery, Sentinel-1 will guarantee an increasing use of MTI for ground displacement investigations. The present work discusses opportunities of MTI applications to ground instability monitoring by assessing the performance of the different available satellite missions, according to acquisition parameters such as wavelength, spatial resolution, revisit time and orbital tube size. This performance analysis allows to foresee the quality of displacement maps estimated through MTI according to mission characteristics, and thus to support SAR data selection. In particular, a comparative analysis is carried out, aimed at addressing specific advantages of different satellite missions in L-, C- and X-band. For instance, high resolution data increase the density of coherent targets, thus improving the monitoring of local scale events. Short (X-band) wavelengths improve the sensitivity to displacements. Short revisit times allow collecting large data stacks in short times, and improve the temporal sampling, thus increasing the chances to catch pre-failure signals (high-rate, nonlinear signals). The precision of the displacement rate detection depends on the number of images and on the phase noise, while the precision of the residual height error estimation depends also on the orbital tube size. Sentinel-1 will provide data for the next years with short revisit time, and it is thus likely to provide reliable displacement estimations at large scale, and in quite limited observation time spans. However, due to its narrow orbital tube size, it has a limited height precision, which leads to poor geo-location quality. An example of multi-sensor ground instability investigation is also presented concerning the site of Marina di Lesina, in Southern Italy, where several SAR datasets are available acquired from ERS, ENVISAT, Radarsat-2, COSMO-SkyMed and Sentinel-1, covering more than 20 years with varying ground resolutions, frequency bands and repeat times. The site is affected by sinkholes and uplifting caused by the interaction between the water coming from an artificial canal and the underground soil where gypsum with residual anhydride is present. The data at C-band and medium resolution from ERS and ENVISAT are able to catch the large scale uplift pattern, since the available observation time span is suitable to provide the required velocity precision. Radarsat-2 data improve the spatial density of detected targets, while, as foreseen by the model, Sentinel-1 improves the C-band performance, by providing, in a limited time span, precise estimation of the displacement rates. Finally, as expected, high resolution data from COSMO-SkyMed lead to a considerable increase of the PS spatial density, which allows to improve the delineation of the spatial -370- deformation pattern. High resolution / short revisit time data are also very promising for detecting small precursory terrain movements related to the sinkholes.
Work supported by the project “APULIA SPACE” (PON03PE_00067_6), PON Ricerca e competitività 2007-2013.
[Ref.Fringe2017] Refice A., Bovenga F., Belmonte A., D'Addabbo A., Pasquariello G., Nutricato R., Nitti D. O., "Estimating and modeling coherence on multi-temporal, short-revisit, long stacks of SAR data". In: Abstract Book of the Fringe 2017 Workshop - the 10th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR", 5-9 June 2017, Helsinki, Finland. URL: http://fringe.esa.int/files/Fringe2017_Abstract_Book_FINAL.pdf
The recent availability of large amounts of remotely sensed data requires setting up efficient paradigms for the extraction of information from long series of multi-temporal, often multi-sensor, datasets. In this field, monitoring of terrain instabilities is currently performed through algorithms which estimate millimetric displacements of stable (coherent) objects, through analysis of stacks of SAR images acquired in interferometric mode. The result is generally a decomposition of at least part of the complete complex covariance matrix obtained from all possible pairwise combinations of the images in the stack, separating its spatially- and temporally-correlated parts. The same SAR temporal data stacks can be used to apply change detection algorithms, to reveal, over potentially huge spatial scales and with high resolution, terrain surface changes due to e.g. environmental hazards (floods, fires, earthquakes). In this case, again, the temporal covariance matrix contains in practice all the information related to the environmental changes. The covariance matrix, or its normalized version, known as coherence matrix, expresses thus all the information content related to a time series of remotely sensed, coherent data. In the case of SAR data, this kind of representation offers a unified framework for the study of phenomena linked either to the presence of “periods” of persistent scattering characteristics, or to changes of backscattering patterns, hinting to variations in the terrain characteristics. The average operation, involved in the definition of the above-mentioned covariance and coherence matrices, has to be performed necessarily over “homogeneous” pixel sets. This homogeneity criterion can be intended in various ways, including the one connected to the covariance definition itself, thus leading to a sort of recursive estimation process. Moreover, such homogeneity measures are often used as a substitute for the classical Euclidean distance in nonlocal estimate implementation frameworks, used for instance in the design of effective SAR speckle filters. The coherence matrix highlights the role of the interferometric phase. After having suitably modeled various phase contributions, due to topography, atmosphere, etc., it is possible to detect periods in which a target remains stable, and can thus be used as a benchmark for estimating ground deformations or other effects related to the variations of the signal optical path. From the above discussion, it appears that a thorough, physically based modeling of the coherence over such long times series of SAR data constitutes a priority for efficient data exploitation. We illustrate some of the inference which can be made starting from a time series of more than a hundred COSMO-SkyMed (CSK) images acquired in InSAR mode over the Haiti capital of Port-Au-Prince, spanning a period of almost 3 years with short repeat times. Such tight acquisition schedule can be obtained nowadays with latest-generation SAR constellations such as CSK or (at lower resolutions) Sentinel-1A/B. On the mentioned CSK dataset, some recently proposed models for coherence have been tested over selected regions of interest, covering different terrain types, from forest, to cultivations, to man-made smooth surfaces such as tarmac lanes, to built-up areas. Coherences are estimated over homogeneous pixel sets determined through a nonlocal criterion. Results may help shed some light on the nature of constant, decaying and periodic components of the InSAR coherence.
Work supported by the Italian project “APULIA SPACE” (PON03PE_00067_6), PON Ricerca e competitività 2007-2013.
[Was.Fringe2017] Wasowski J., Bovenga F., Nutricato R., Nitti D. O., Chiaradia M. T., "Sentinel-1 Data Help Capture Pre-failure Signatures of Slope Instability – Toward Forecasting of the Temporal Occurrence of Landslides with the Aid of Multi-temporal Interferometry". In: Abstract Book of the Fringe 2017 Workshop - the 10th International Workshop on "Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR", 5-9 June 2017, Helsinki, Finland. URL: http://fringe.esa.int/files/Fringe2017_Abstract_Book_FINAL.pdf
The regularity and higher frequency of acquisitions of Sentinel-1A/B (S-1) with respect to earlier ESA’s satellite C-band sensors (ERS1/2, ENVISAT) represent clear advantages for users of multi-temporal interferometry (MTI) products. The utility of the IW acquisition mode of S-1 for regional scale slope instability detection through MTI has already been demonstrated, e.g., via studies of landslide-prone areas in Italy. In this work, we explore the potential of S-1 data for local (site-specific) scale landslide monitoring and capturing pre-failure signs of slope instability. This is done by using examples of two unstable slopes from different environmental settings and MTI through the Persistent and Distributed Scatterers processing capability of the SPINUA algorithm. The first case regards a hilltop town in the Apennine Mts., whose stability is threatened by a large (~600 x 300 m2), slow moving deep landslide. We processed over 50 S-1A images acquired since October 2014. The comparison of the MTI results with those based on ERS and ENVISAT imagery shows that a much higher number of radar targets is obtained from S-1A data (e.g., from ~2 to 5 times higher, respectively on the landslide and in the overall area of interest, including also the town and peri-urban areas). With more targets, we can better depict the spatial movement pattern and local velocity gradients, which is important for geotechnical assessment. Furthermore, the lateral boundaries of the landslide can now be delimited in more detail, overcoming the mapping uncertainties typical in cases of very slow, deep landslides affecting urbanized areas. This offers invaluable information for local inhabitants/property owners and for engineering scale hazard assessment. Importantly, the MTI from S-1A data also revealed an accelerating trend with a nearly doubled velocity of the displacements with respect to those in the earlier period covered by ERS-ENVISAT data. The higher frequency of S-1A acquisitions (about 30/year in this case) helped highlighting the non-linearity of surface deformations within the faster displacement phase, whose timing was consistent with the increase in landslide movements detected through subsurface inclinometer monitoring and field observations. The latter demonstrated that this faster movement phase coincided with (or was preceded by) a failure of the landslide toe, which occurred in the inhabited area. The second case represents an example of a retrospective investigation of a huge (over 2 km long, few tens of m deep) landslide, which occurred in 2016 in an important open-cast coal mine in central Europe. The apparently sudden failure disrupted the mining operations, destroyed in part the mining machinery and resulted in high economic losses. In this case, we exploited over 60 S-1A/B images acquired since November 2015. Despite the presence of spatial gaps in information (due to intensive surface disturbance by mining operations), the MTI results provided a good overview of the ground instability/stability condition within and outside the active mine. Furthermore, it was shown that the 2016 slope failure was preceded by very slow (generally 1-3 cm/yr) creep-like deformations, already detectable in 2014. Although it would not have been simple to issue a short-term warning of the impeding failure based on the displacement time series, the MTI results showed that the slope had been in the critical instability state some months prior to the landslide event. Furthermore, the spatio-temporal mapping of coherence changes in the unstable area indicated a sharp coherence loss in the last few weeks before the slope collapse. The above examples demonstrate that by securing long-term, regular, high-frequency acquisitions over wide-areas, the Sentinel-1 mission facilitates a more effective use of MTI in slope hazard assessment. We note further improvement thanks to the availability of S-1B data (e.g., more frequent measurements to forewarn potential instability hazards). This has practical impacts on landslide monitoring activities and will aid future research on slope failure forecasting. Thanks to this and free imagery, the site-specific investigations relying on MTI will become even more feasible and cost-effective for non-scientific users (e.g., engineering geology/geotechnical consulting) and commercial services (e.g., Rheticus®).
We thank ESA for ERS, ENVISAT and Sentinel-1 & Sentinel-2 data.
Other poster/slideshow presentations
[Bol.RSCYS2017] Stelios Bollanos, Yiota Spastra, Ilias Ioannou, Vicky Avgikou, Claudio Lamantia, Vincenzo Massimi, Paolo Manunta, Vito De Pasquale, Cristoforo Abbattista, Leonardo Amoruso, Luigi Agrimano, Sergio Samarelli, Mauro Casaburi, Raffaele Nutricato, Alberto Morea, Khalid Tijani, Davide Oscar Nitti, Maria Teresa Chiaradia, "RHETICUS: GEO-ANALYTICS INFORMATION BY SUBSCRIPTION BASED ON FUSION OF EARTH OBSERVATION AND INSPIRE DATA FOR MONITORING CRITICAL INFRASTRUCTURE AND THE ENVIRONMENT", Fifth International Conference on Remote Sensing and Geoinformation of Environment (RSCY2017) - CYPRUS - March 20-23, 2017
Rheticus® is the Planetek cloud-based data and services hub able to process radar and optical data from multiple open-data satellite constellations designed to continuously deliver updated geoanalytics information through complex automatic processes and minimum interaction with human beings. Among the peculiarities of Rheticus, there is the capability to integrate, in the processing algorithms, ancillary data, gathered in different ways from different data sources and channels, either for validation purposes or for increasing the information resolution enabled by the EO data used. “Rheticus displacement” represents a revolutionary model concept (through subscription) in monitoring Critical Infrastructure (dams, pipelines, bridges etc) with the use of SAR data and the Persistent Scatterers technique (PS), designed for users with high expectations in the value of information and its user friendliness provision. A further characteristic of Rheticus is the ability to act as an interoperable service node offering processing capabilities within a wider Big Data infrastructure. This concept is applied in the on-going ESA project CTEP (Coastal Thematic Exploitation Platform), which is addressing the coastal theme in the context of the Thematic Exploitation Platform initiative, whose purpose is to exploit EO big data for the provision of a set of data and tools for thematic communities of users. This objective is achieved by means of a widely distributed architecture, which envisages the cooperation among the mother CTEP platform, and the children CTEPs. In the overall architecture, Rheticus plays the role of child CTEP serving specific needs of the Mediterranean users’ community. In this paper is described how Rheticus applies the Big Data concepts through the fusion of EO and ancillary data – with a particular attention to INSPIRE data – operated through a Big Data infrastructure. This infrastructure supports the batch processing of a continuously increasing volume of data for the generation of actionable knowledge based on geoanalytics indexes and graphs provided through user friendly dynamic reports.
Rheticus® is a registered trademark of Planetek Italia srl. The research is partly co-funded in the framework of the FAST4MAP project (ASI Contract n. 2015-020-R.0). Sentinel-1A products provided by ESA. CSK® Products provided by ASI under a license to use.
[Bov.CSK_WS2017] F. Bovenga, A. Refice, G. Pasquariello, A. Belmonte, R. Nutricato, D. O. Nitti, M. T. Chiaradia, "Exploitation of multi-temporal and multifrequency potential of COSMO-SkyMed". COSMO-SkyMed Workshop, 13-15 November 2017, ASI – Roma.
[Pas.SIGEA2017] G. Pasquariello, "Sistemi da Satellite per il Monitoraggio dei Fenomeni Franosi", Convegno SIGEA "Analisi e attività di mitigazione del dissesto idrogeologico", Foggia, martedì 6 giugno 2017.
Attività svolte da A. Belmonte, F. Bovenga, G. Pasquariello, A. Refice, D.O. Nitti, R. Nutricato, M. T.Chiaradia,L. Guerriero, J. Wasowsky, R. Pellicani, G. Spilotro. Work supported by: Convenzione AdB-Puglia – ISSIA Studio dei fenomeni di subsidenza nel subappennino Dauno e Capitanata tramite interferometria radar multitemporale (2006); PRIN2008 METODOLOGIE AVANZATE NELLA VALUTAZIONE E MITIGAZIONE DEL RISCHIO DA FRANA, "APULIA SPACE" (PON03PE_00067_6), PON Ricerca e competitività 2013-2016. The CSK imagery for the Zhouqu site, China was provided by the ASI within the COSMO-SkyMed AO Project ID 1820. ENVISAT and CSK data for Assisi (Italy) were provided respectively by the European Space Agency (ESA) and ASI in the framework of the MORFEO project funded by ASI (Contract no. I/045/07/0). Marina di Andora results were obtained in the framework of projects "CAR-SLIDE - Mapping and monitoring system for landslides forecast" (PON R&C 2007-2013) and "ADF - Archiving Data Fusion". CSK products processed under a license of ASI "Original COSMO-SkyMed Product - Agenzia Spaziale Italiana - (2013-2014). All rights reserved".
[Bru.ICS2016] Bruno, M. F., Molfetta, M. G., Mossa, M., Nutricato, R., Morea A. and Chiaradia, M. T., "Coastal observation through COSMO-SkyMed high-resolution SAR images," In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Volume 1, Special Issue 75, pp. 795–799. Coconut Creek (Florida), Print ISSN: 0749-0208. Online ISSN: 1551-5036. Scopus: 2-s2.0-84987719053. WOS:000373241300014 DOI: http://dx.doi.org/10.2112/SI75-160.1 IF: 0.915 (Year: 2016 - Source: https://goo.gl/Xcc3cT)
The study deals with the application and further improvement of an advanced Earth Observation system, named COSMO-Beach, developed for semi-automatic shoreline extraction and coastal morphology identification. The system exploits SAR Single-Look-Complex data acquired by the COSMO-SkyMed constellation, which is able to provide X-band images with a short revisiting time. The implemented procedures have been tested over a very popular beach in Apulia Region (Italy), affected by erosion problems induced by human activities. The outcomes of the COSMO-Beach system are presented and discussed.
[Ref.EES2016] A. Refice, G. Pasquariello, F. Bovenga, V. Festa, P. Acquafredda, G. Spilotro, "Investigating uplift in Lesina Marina (Southern Italy) with the aid of persistent scatterers SAR interferometry and in situ measurements". Environmental Earth Sciences (2016) 75:243. DOI:10.1007/s12665-015-4979-1. Scopus:2-s2.0-84955457462. WOS:000370241400065. ISSN: 1866-6280. eISSN: 1866-6299. IF(2018):1.871; IF(5years):2.032 (Source:WOS).
We apply persistent scatterer interferometry (PSI) techniques to synthetic aperture radar (SAR) data from ERS and ENVISAT satellites on the Lesina Marina area, a coastal tourist village in Apulia, Southern Italy, where the excavation of a canal exposed grey micro- and meso-crystalline gypsum which is now showing a high density of cavities and sinkholes due to gravitational collapse processes. We observe PS objects undergoing displacements, along the sensor line of sight, forming the same relatively smooth pattern in all the processed data stacks. Vertical displacement rates, derived through integration of ascending and descending geometries, reach about 4 mm/year on locations adjacent to the canal, gently decreasing towards the western end of the built-up area. High-precision leveling measurements, performed in 1999 and 2010, reveal a substantial agreement with the ENVISAT PSI data, taking into account a small bias due to the choice of the leveling reference point. The dataset, thus validated, suggests the presence of an uplift phenomenon going on steadily for the entire timespan covered by the SAR observations (1992\u20132009). These observations, supported by petrographic data and in situ investigations, seem only in part compatible with a residual diapirism, and hint instead to more complex processes, such as a combination of diapirism and the hydration of the residual anhydrite in the core of the gypsum mass. These results confirm the importance of the integration between in situ, geologic and geophysical, remotely sensed investigations, as the latter often represent an essential tool to infer whether a given phenomenon, which can be hypothesized by the former, is presently under development.
"Research funded through the Italian Ministry of
Research—PRIN 2008 research grant ‘‘Advanced technologies in the
assessment and mitigation of the landslide risk: precursors detection,
previsional models and thematic mapping’’. ENVISAT and ERS data
are copyright of European Space Agency—provided under Category-
1 project N. 5367, ‘‘Subsidence monitoring in Daunia and Capitanata
(Puglia Region, Italy) through multi-temporal point-target DInSAR
techniques’’. GAP srl personnel is acknowledged for aid in InSAR
processing."
International Conference Proceedings
[Bru.EESMS2016] M. F. Bruno, M. G. Molfetta, M. Mossa, R. Nutricato, D. O. Nitti, L. Guerriero, A. Morea, M. T. Chiaradia, A. Coletta, "Integration of Multitemporal SAR/InSAR Techniques and NWM for Coastal Structures Monitoring: Outline of the software system and of an operational service with COSMO-SkyMed data," Proc. of 2016 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems (EESMS), Bari (Italy), 13-14 June 2016, p.186-191 (2016). Scopus: 2-s2.0-84980349560. ISBN: 978-1-5090-2369-1. DOI: 10.1109/EESMS.2016.7504837. IF: 1.06 (Year: 2015 - Source: ResearchGate - https://goo.gl/ouCTJE)
Continuous monitoring of coastal areas is a necessary condition for proper coastal activities regulation. Coastal area alterations, even in the short term, in fact, may lead to a significant social change in the development of economic activities and lifestyle in populations living in coastal regions. This paper deals with the development of an integrated operational Earth Observation system aimed to provide a complete monitoring system for both natural and built coastal environments. Three different software engines have been coupled to fully exploit the COSMO-SkyMed images using SAR and InSAR techniques (SPINUA and COSMO-Beach modules) providing also APD corrections computed using numerical weather simulations (NWM module). This allows to automate the entire radar image process chain to obtain a complete picture of the most important phenomena for large and small scale. The implemented system has been widely tested on COSMO-SkyMed images taken within the Map Italy program over two different Italian sites and results are presented and discussed.
[Tij.EESMS2016] K. Tijani, A. Morea, M. T. Chiaradia, R. Nutricato, L. Guerriero, "Prototype of a multi-platform remote sensing service for fishing forecasting", Proc. of 2016 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems, p.237-242 (2016). Scopus: 2-s2.0-84980370560. ISBN: 978-1-5090-2369-1. DOI: 10.1109/EESMS.2016.7504846.
The present work concerns the development of an automatic Fishing Forecasting System (FiFoS) where satellite observations, ancillary data and in situ measurements (Catch Per Unit Effort) are used to set up, calibrate and validate a fishing forecasting model. Multi-temporal and multi-sensor data fusion techniques are applied to multi-spectral data in order to detect chlorophyll and sea temperature fronts that according to physical models of the upwelling phenomena are related to areas rich of phytoplankton nutrients where a high concentration of pelagic fish is expected.
Work partly supported in the framework of the project “Sustainable Fishery", funded by Apulia Region – Italy (FEP 2007-2013 - Measure 3.1) aimed at the development of a near-real-time fishery forecasting system in the Adriatic Sea based on satellite data. In-situ data of the 2013 and 2014 fishing seasons were provided by FEDERPESCA (Federazione Nazionale delle Imprese di Pesca). The authors wish to thank Dr. Luigi Giannini of FEDERPESCA and Guido Pasquariello of CNR ISSIA for interesting discussions that further stimulated the improvement of the FiFoS system.
[Nit.SPIE2016] D. O. Nitti, A. Morea, R. Nutricato, M. T. Chiaradia, C. La Mantia, L. Agrimano, S. Samarelli, "Automatic GCP extraction with high resolution COSMO-SkyMed products", Proc. SPIE 10003, SAR Image Analysis, Modeling, and Techniques XVI, 1000302 (October 18, 2016), 12 pages; Scopus: 2-s2.0-85010842041. WOS:000391442000001. ISBN:978-1-5106-0411-7. ISSN: 0277-786X. doi:10.1117/12.2241281
High-resolution Synthetic Aperture Radar (SAR) data represent an essential resource for the extraction of Ground Control Points (GCP) with sub-metric accuracy without in situ measurement campaigns. Conceptually, SAR-based GCP extraction consists of the following two steps: (i) identification of the same local feature on more SAR images and determination of their range/azimuth coordinates; (ii) spatial 3D positioning retrieval from the 2D radar coordinates, through spatial triangulation (stereo analysis) and inversion methods. In order to boost the geolocation accuracy, SAR images must be acquired from different line of sights, with intersection angles typically wider than 10 degrees, or even in opposite looking directions. In the present study, we present an algorithm specifically designed for ensuring robustness and accuracy in the fully automatic detection of bright isolated targets (steel light poles or towers) even when dealing with opposite looking data takes. In particular, the popular Harris algorithm has been selected as detector because it is the most stable and robust-to-noise algorithm for corners detection on SAR images. We outline the designed algorithmic solution and discusses the results derived over the urban area of Pisa (Italy), where more than ten COSMO-SkyMed Enhanced Spotlight (ES) stereo images are available, thus resulting an optimal test site for an assessment of the performances of the processing chain. The experimental analysis proofs that, assumed timing has been properly recalibrated, we are capable to automatically extract GCP from CSK ES data takes consisting in a very limited number of images.
[Nut.SPIE2016] R. Nutricato, A. Morea, D. O. Nitti, C. La Mantia, L. Agrimano, S. Samarelli, M. T. Chiaradia, "Automatic SAR/optical cross-matching for GCP monograph generation", Proc. SPIE 10003, SAR Image Analysis, Modeling, and Techniques XVI, 1000303 (October 18, 2016), 8 pages; Scopus: 2-s2.0-85010868614. WOS:000391442000002. ISBN:978-1-5106-0411-7. ISSN: 0277-786X. doi:10.1117/12.2241284
Ground Control Points (GCP), automatically extracted from Synthetic Aperture Radar (SAR) images through 3D stereo analysis, can be effectively exploited for an automatic orthorectification of optical imagery if they can be robustly located in the basic optical images. The present study outlines a SAR/Optical cross-matching procedure that allows a robust alignment of radar and optical images, and consequently to derive automatically the corresponding sub-pixel position of the GCPs in the optical image in input, expressed as fractional pixel/line image coordinates. The cross-matching in performed in two subsequent steps, in order to gradually gather a better precision. The first step is based on the Mutual Information (MI) maximization between optical and SAR chips while the last one uses the Normalized Cross-Correlation as similarity metric. This work outlines the designed algorithmic solution and discusses the results derived over the urban area of Pisa (Italy), where more than ten COSMO-SkyMed Enhanced Spotlight stereo images with different beams and passes are available. The experimental analysis involves different satellite images, in order to evaluate the performances of the algorithm w.r.t. the optical spatial resolution. An assessment of the performances of the algorithm has been carried out, and errors are computed by measuring the distance between the GCP pixel/line position in the optical image, automatically estimated by the tool, and the “true” position of the GCP, visually identified by an expert user in the optical images.
[Sam.SPIE2016] S. Samarelli, A. P. Lorusso, L. Agrimano, R. Nutricato, F. Bovenga, D. O. Nitti, M. T. Chiaradia, "Rheticus: an automatic cloud-based geo-information service platform for territorial monitoring", Proc. SPIE 10003, SAR Image Analysis, Modeling, and Techniques XVI, 100030M (October 18, 2016), 7 pages. Scopus: 2-s2.0-85010911799. WOS:000391442000014. ISBN:978-1-5106-0411-7. ISSN: 0277-786X. doi: 10.1117/12.2241285
Rheticus® is an innovative cloud-based data and services hub able to deliver Earth Observation added-value products through automatic complex processes and, if appropriate, a minimum interaction with human operators. In this paper, we outlines the capabilities of the “Rheticus® Displacement” service, designed for geohazard and infrastructure monitoring through Multi-Temporal SAR Interferometry techniques.
[Dad.EESMS2016] A. D’Addabbo, A. Refice, G. Pasquariello, F. Lovergine, S. Manfreda, "Following Flood Dynamics by SAR/Optical Data Fusion", Proceedings of the 2016 IEEE Workshop on Environmental, Energy, and Structural Monitoring Systems (EESMS). DOI:10.1109/EESMS.2016.7504848. Scopus:2-s2.0-84980360416. WOS:000386794700045. Electronic ISBN: 978-1-5090-2370-7. Print on Demand(PoD) ISBN:978-1-5090-2371-4.
Synthetic aperture radar (SAR) acquisitions are particularly useful to produce flood maps thanks to their all-weather and day-night capabilities. However, repetition intervals of radar instruments are in the order of several days for routine operations, reaching daily or higher frequencies only in tasked conditions. Therefore, to follow flood dynamics, images acquired by different sensors at different times may be beneficial. In the present work, multi-temporal SAR intensity, InSAR coherence and optical data are considered to describe a flood event occurred in the Basilicata region (southern Italy) on December 2013. In this case study, optical data have a twofold role: they allow to follow the flood dynamics (because SAR and optical data have been acquired in different dates during the inundation event), and they add information concerning the land cover of the analyzed area. The data fusion approach is based on Bayesian Networks (BNs). It is shown that the synergetic use of different information layers can help detect more precisely the areas affected by the flood, reducing false alarms and missed identifications which may affect algorithms based on data from a single source. The produced flood maps are compared to reference maps, independently obtained; the comparison indicates that the proposed methodology is able to reliably follow the temporal evolution of the phenomenon, assigning high probability to areas most likely to be flooded, reaching accuracies of up to 89%.
COSMO-SkyMed images are courtesy of Italian Space Agency. Ing. L. Candela, ASI, is kindly acknowledged for support in data acquisition. InSAR processing was performed by Dr. D. O. Nitti of GAP s.r.l.
Conference Abstracts
[Was.EGU2016] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, M. T. Chiaradia, A. Refice and G. Pasquariello, "Exploring the potential of Sentinel-1 data for regional scale slope instability detection using multi-temporal interferometry", Abstracts proceedings EGU 2016, Vienna, Austria, 17-22 April 2016. Abstract ID-No: EGU2016-12505. Vol. 18, eISSN: 1607-7962. URL: http://meetingorganizer.copernicus.org/EGU2016/EGU2016-12505.pdf
Launched in 2014, the European Space Agency (ESA) Sentinel-1 satellite carrying a medium resolution (20 m) C-Band Synthetic Aperture Radar (SAR) sensor holds much promise for new applications of multi-temporal interferometry (MTI) in landslide assessment. Specifically, the regularity of acquisitions, timeliness of data delivery, shorter repeat cycle (currently 12 days with Sentinel-1A sensor), and flexible incidence angle geometry, all imply better practical utility of MTI relying on Sentinel-1 with respect to MTI based on data from earlier ESA’s satellite radar C-band sensors (ERS1/2, ENVISAT). Furthermore, the upcoming launch of Sentinel-1B will cut down the repeat cycle to 6 days, thereby further improving temporal coherence and quality and coverage of MTI products. Taking advantage of the Interferometric Wide (IW) Swath acquisition mode of Sentinel-1 (images covering a 250 km swath on the ground), in this work we test the potential of such data for regional scale slope instability detection through MTI. Our test area includes the landslide-prone Apennine Mountains of Southern Italy. We rely on over 30 Sentinel-1 images, most of which acquired in 2015, and MTI processing through the SPINUA algorithm (Stable Points INterferometry in Un-urbanized Areas). The potential of MTI results based on Sentinel-1 data is assessed by comparing the detected ground surface displacements with the MTI results obtained for the same test area using the C-Band data acquired by ERS1/2 and ENVISAT in 1990s and 2000s. Although the initial results are encouraging, it seems evident that longer-term (few years) acquisitions of Sentinel-1 are necessary to reliably detect some extremely slow movements, which were observed in the last two decades and are likely to be still present in peri-urban areas of many hilltop towns in the Apennine Mts. The MTI results obtained from Sentinel-1 data are also locally compared with the MTI outcomes based on the high resolution (3 m) TerraSAR-X imagery. Again, even though there is lack of temporal overlap in the two datasets, the comparison shows some potential benefits of the exploitation different resolution sensor datasets. For example, when considering the costs of MTI applications, an effective approach to slope hazard assessment could rely on the use of coarser imagery MTI to secure long-term wide-area coverage, to be integrated by higher resolution MTI with more focus on urbanized or greater value areas (cf., Wasowski and Bovenga et al., 2014a,b). Now these approaches are facilitated by the regular global coverage and free medium resolution imagery guaranteed by the background satellite radar mission of Sentinel-1.
Study carried out in the framework of the Apulia Space project (PON&REC 2007-2013, Cod: PON03PE_00067_6). We also thank ESA and the German Space Agency (DLR) for providing us radar data.
[Chi.AGU2016] M. T. Chiaradia, S. Samarelli, L. Agrimano, A. P. Lorusso, R. Nutricato, D. O. Nitti, A. Morea, K. Tijani, "Rheticus Displacement: an Automatic Geo-Information Service Platform for Ground Instabilities Detection and Monitoring", AGU Fall Meeting 2016, Abstract ID:155327, Poster Presentation G23A-1039, San Francisco, California, USA, 12-16 December 2016. URL (abstract): https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/155327 URL (Poster): https://agu.confex.com/agu/fm16/mediafile/Handout/Paper155327/AGU2016_poster_Rheticus_v3.pdf
Rheticus® is an innovative cloud-based data and services hub able to deliver Earth Observation added-value products through automatic complex processes and a minimum interaction with human operators. This target is achieved by means of programmable components working as different software layers in a modern enterprise system which relies on SOA (service-oriented-architecture) model. Due to its architecture, where every functionality is well defined and encapsulated in a standalone component, Rheticus is potentially highly scalable and distributable allowing different configurations depending on the user needs. Rheticus offers a portfolio of services, ranging from the detection and monitoring of geohazards and infrastructural instabilities, to marine water quality monitoring, wildfires detection or land cover monitoring. In this work, we outline the overall cloud-based platform and focus on the “Rheticus Displacement” service, aimed at providing accurate information to monitor movements occurring across landslide features or structural instabilities that could affect buildings or infrastructures. Using Sentinel-1 (S1) open data images and Multi-Temporal SAR Interferometry techniques (i.e., SPINUA), the service is complementary to traditional survey methods, providing a long-term solution to slope instability monitoring. Rheticus automatically browses and accesses (on a weekly basis) the products of the rolling archive of ESA S1 Scientific Data Hub; S1 data are then handled by a mature running processing chain, which is responsible of producing displacement maps immediately usable to measure with sub-centimetric precision movements of coherent points. Examples are provided, concerning the automatic displacement map generation process, as well as the integration of point and distributed scatterers, the integration of multi-sensors displacement maps (e.g., Sentinel-1 IW and COSMO-SkyMed HIMAGE), the combination of displacement rate maps acquired along both ascending and descending passes.
[Bov.LSP2016] F. Bovenga, A. Refice, G. Pasquariello, R. Nutricato, D. O. Nitti, J. Wasowski, "Requirements and prospects of landslide analysis through SAR interferometry and recent satellite missions", 2016 European Space Agency Living Planet Symposium, Prague, Czech Republic, 9-13 May 2016. Poster: Paper ID 496. URL: http://lps16.esa.int/files/Contribution496.pdf
Thanks to the all-weather, day-night capability to detect and measure small ground surface deformations, multi-temporal Synthetic Aperture Radar (SAR) Interferometry (InSAR) techniques are attractive for landslide investigations. This Multi-temporal InSAR (MTI) application poses challenges related to the limited spatial extent of the phenomenon, the complexity of the ground deformations, and the occurrence in mountainous and vegetated areas that cause visibility problems. Nowadays, several satellite missions are available providing interferometric SAR data at different wavelengths, spatial resolutions, and revisit time. High-resolution X-Band SAR sensors, such as the COSMO-SkyMed constellation, have recently provided data with spatial resolution reaching metric values, and revisit time up to few days leading to increase the density of the measurable targets as well as to improve the detection of non linear movement. Medium resolution C-band SAR data have been thoroughly exploited in the last two decades thanks to the ERS-1/2, ENVISAT-ASAR and Radarsat missions. A new interesting opportunity is recently provided by Sentinel-1 mission, which has just started to deliver data to the user community. Although the spatial resolution is comparable to previous ESA C-band missions the revisit time is reduced to 12 and 6 days, by considering, respectively, one or two satellites. It is envisioned that by offering regular globe-scale coverage, improved temporal resolution and freely available imagery, Sentinel-1 will guarantee an increasing use of MTI in landslide investigations. These background missions are necessary for long-term, systematic mapping of unstable unstable slopes and regional scale assessment of landslide processes. According to these different SAR space-borne missions, the present work discusses current and future opportunities of MTI applications to slope instability monitoring by addressing, through a simple theoretical model, issues related to slope visibility, sensitivity to ground displacement, coherent target detection, mean velocity precision. In particular a comparative analysis is carried out aimed at investigating specific advantages of different satellite missions with respect to wavelength, resolution, revisit time, and clutter backscatter. According to this analysis, we show that a reliable estimates of the displacement rates are possible in a narrower time span by using X-band than C-band, but Sentinel-1 constellation will improve the performance of C-band. Moreover, for a certain time span the expected velocity STD is better for X-band than for C-band but, again, the Sentinel-1 constellation will improve the performance of C-band. This impacts on the monitoring capabilities in high risk situations by providing results in a shorter time, and allows monitoring mountainous areas during short period avoiding snow coverage, thus maximizing the chance to detect coherent targets. Finally, the work provides examples of multi-sensor and multi-scale slope instability investigations obtained by processing real data from both C-band medium resolution and X-band high resolution SAR data. In particular, the differences between displacement maps in terms number of images, observation time span, number of coherent targets, and estimated displacement precision, are used to support the outcomes of previous model.
[Tij.PhDXXVII] K. Tijani, "Models and Algorithms for Data Fusion of Oceanographic Multi-Source data: application for a sustainable Fishery service". PhD Thesis, Scuola Dottorato di Ricerca in Fisica XXVII Ciclo, Dipartimento Interateneo di Fisica "M. Merlin", Università degli Studi di Bari Aldo Moro. Tutor: Prof.ssa M.T. Chiaradia (DIF-BA). Coordinatore: Prof. G. Scamarcio (DIF-BA). SSD: FIS/01
By mapping the concentration of chlorophyll (CHL) and the temperature of the sea surface (SST), satellite images reveal the complex dynamics of marine waters and prove to be a very powerful tool when used to detect potential fishing areas, significantly reducing the time of the search, the fuel consumption and the human effort, and simultaneously increasing the CPUE (catch per unit effort). In the present PhD work, various techniques of multi-sensor, multi-resolution and multitemporal data fusion are applied to multi- spectral satellite image data of MODIS-AQUA, MODIS-TERRA and VIIRS sensors, in order to detect "fronts" of chlorophyll concentration and temperature on the sea surface. According to the physical model of the phenomena, these fronts are generated by the upwelling of cold waters rich in nutrients (phytoplankton) which correspond to areas with a high concentration of pelagic fish and are characterized by high values of local gradients of SST and CHL with anti-parallel orientation. Therefore, the organization of thesis follows the processing levels of satellite raw data, for the evaluation of geophysical parameter and the main procedure step to identify areas of high abundance of fish. Chapter 1 focuses on the general description of the research issue and the objectives of this research. Chapter 2 gives a literature review on data fusion techniques and pixel-based average. Chapter 3 discusses the state of the art of ocean color and temperature from satellite remote sensing. The description of the study area, the imagery and in situ data, used in this research, is given in Chapter 4. Chapter 5 discusses the algorithms for geophysical parameters retrieval. Chapter 6 describes the multi-scale edge detection methodology and a procedure for its parameters optimization. The upwelling phenomenon and its implementation in the model are detailed in Chapter 7, and summarize the main achieved results. Finally, the conclusions obtained from this study. Recommendations for further studies are also presented in this section.
[Con.PhDXXVI] D. Conte, "Caratterizzazione di bersagli non cooperanti e misure di quota di precisione mediante tecniche interferometriche e radargrammetriche multitemporali con immagini satellitari acquisite dalla costellazione COSMO-SkyMed". PhD Thesis, Scuola Dottorato di Ricerca in Fisica XXVI Ciclo, Dipartimento Interateneo di Fisica "M. Merlin", Università degli Studi di Bari Aldo Moro. Tutor: Prof.ssa M.T. Chiaradia (DIF-BA). Co-Tutor: dott. F. Nirchio (ASI). Coordinatore: Prof. G. Scamarcio (DIF-BA). SSD: FIS/01
"Il lavoro di tesi è dedicato all’estrazione di valori di quota da dati SAR mediante tecniche di visione stereo, quali la radargrammetria (StereoSAR) e l’interferometria (InSAR), e all’analisi dei risultati realizzata per mezzo di dati di riferimento a copertura globale, come i DEM (Digital Elevation Model) e locale, quali i dati GPS ed i PS (Persistent Scatterers), con l’obiettivo di confrontare le prestazioni delle tecniche e le loro potenzialità, relativamente alla generazione di mappe topografiche da acquisizioni con sensori radar di ultima generazione. Il progetto, finanziato dall’ASI (Agenzia Spaziale Italiana), ha fatto uso di immagini COSMO-SkyMed (COstellation of small Satellites for Mediterranean basin Observation) in modalità di acquisizione SPOTLIGHT ed è stato condotto sull’area di Parkfield, una cittadina della California che sorge sulla faglia di San Andreas a cavallo della placca Nordamericana lungo quella del Pacifico. L’area risulta uno dei luoghi più monitorati al mondo per l’intensa attività sismica, per i suoi effetti e per i segni premonitori. Nell’ambito del primo Announcement of Opportunity, l’Agenzia Spaziale Italiana ha individuato Parkfield come sito benchmark, e pertanto conta attualmente di un elevatissimo numero di acquisizioni CSK. Oltre alla quantità di immagini disponibili, il sito offre i seguenti vantaggi relativi al mapping topografico quali: la notevole escursione dei valori di quota ortometrica, compresa dai circa 400m ad un massimo di circa 1300m in un raggio di 10km dall’abitato di Parkfield; orografia del terreno con pendenze locali comunque contenute (inferiori ai 20° su quasi tutta l’area di interesse) con conseguente estensione delle aree occultate per effetto delle distorsioni SAR (quali layover e shadow) trascurabile nelle diverse acquisizioni disponibili. Ricordiamo che la costellazione COSMO-SkyMED è composta da 4 satelliti (CSK) di medie dimensioni denominati, specificando il numero del sensore, da CSK-S1, …, fino a CSK-S4, ognuno dei quali equipaggiato di un radar ad apertura sintetica (SAR) a microonde con alta risoluzione in banda X. Maggiori informazioni sulla geometria della costellazione, sulle modalità di acquisizione di ogni singolo sensore e sui prodotti standard e di alto livello forniti sono reperibili nei documenti. COSMO-SkyMED è stato concepito come un sistema multi-missione in grado di acquisire fino a 1800 immagini al giorno e di integrarsi con altri sistemi spaziali allo scopo di soddisfare le esigenze di una vasta comunità di utenze. Grazie alla possibilità di illuminare la medesima area di interesse al suolo da differenti direzioni di puntamento (left/right looking), con differenti angoli di incidenza (multi-beam capability) e lungo passaggi sia ascendenti che discendenti, il sistema COSMO-SkyMED mostra di possedere notevolissime potenzialità nel monitoraggio del territorio ed in particolare nel campo del topographic mapping. Il sistema consente la copertura globale del nostro pianeta operando in qualsiasi condizione meteorologica ""all-weather"" e di illuminazione ""night-day"" e fornisce immagini in tre diverse modalità: SCANSAR a più bassa risoluzione, STRIPMAP ed ENHANCED SPOTLIGHT IMAGE a più elevata risoluzione spaziale. I tempi di risposta sono molto contenuti, a seconda della modalità operativa (routine, crisi, emergenza). È opportuno sottolineare che la missione CSK non ha come specifico obiettivo la produzione di DEM, essendo maggiormente indirizzata alla osservazione del suolo sia in ambito militare (per operazioni di intelligence in aree critiche), sia per scopi civili nella prevenzione ambientale. Si è però voluto sperimentare la propensione di questi dati ad ottenere mappe di quota che fossero confrontabili con le più alte specifiche di qualità dei DEM.
La tesi si compone di cinque Capitoli sinteticamente descritti di seguito. Il Capitolo 1 descrive le caratteristiche di un modello digitale del suolo (DEM) con particolare riferimento alle unità di misura normalmente utilizzate e alle diverse specifiche di qualità, quali l’accuratezza, la risoluzione geometrica, nonché i contributi di errore riferiti alle coordinate planimetriche e alla quota. Nel Capitolo 2 vengono descritti i principali parametri geometrici di acquisizione SAR, e viene studiata in dettaglio la radiometria e la statistica del segnale SAR prodotto da un unico sensore e da una coppia di sensori in configurazione stereo. Tale analisi conduce a definire i limiti di errore legati alla radiometria secondo l’analisi di Cramer-Rao. In particolare è stato condotto il calcolo della disuguaglianza di Cramer-Rao in modalità rigorosa a partire dalla distribuzione congiunta delle variabili aleatorie in gioco per una configurazione interferometrica. La generazione di DEM per mezzo di una visione stereo di una stessa scena a suolo, realizzata per mezzo di sensori attivi può realizzarsi attraverso il segnale di fase (Interferometria SAR) o di ampiezza (radargrammetria). L’interferometria SAR usa direttamente il differente cammino ottico della radiazione elettromagnetica nelle 2 acquisizioni, che viene misurato per mezzo della fase interferometrica a valle del phase unwrapping. La radargrammetria usa lo spostamento relativo apparente dei pixel di un’immagine SAR, definito rispetto ad un riferimento comune (parallasse), chiamato disparità che risulta proporzionale alla quota relativa dei punti associati. Il Capitolo 3 esamina entrambe le configurazioni, fornendo una comparazione delle prestazioni e degli errori peculiari per ciascun sistema. Il Capitolo 4 è il primo dei capitoli dedicati all’analisi sperimentale compiuta sui dati provenienti dalla costellazione COSMO-SkyMed; dopo una breve descrizione del sistema, viene motivata la scelta del sito di indagine (Parkfield - California). Su tale area sono stati selezionati i dataset di immagini per generare i diversi prodotti di quota e le informazioni associate quali mappe di coerenza, di correlazione, e mappe di Persistent Scatterers necessarie per l’analisi di qualità dei DEM. Infine l’ultimo Capitolo presenta le valutazioni sui prodotti ottenuti. A tale scopo sono state condotte analisi comparative sia con dati storici (ottenuti da altre missioni) che con dati appositamente generati tramite tecniche interferometriche multitemporali ad alta precisione.
Le immagini sono state scelte consultando il catalogo E-Geos; la scelta ha tenuto conto delle caratteristiche geometriche delle acquisizioni (angoli di look, e direzione di propagazione), della data di acquisizione, dell’area comune ricoperta dalle acquisizioni. I software usati sono differenti per i due approcci radargrammetrico e interferometrico. Per quanto concerne la radargrammetria, i prodotti sono stati realizzati mediante l’uso di “Erdas Imagine” con il quale sono stati generati due DEM radargrammetrici, insieme alle mappe di correlazione e di disparità; queste ultime, inizialmente in coordinate SAR, sono state riportate nella stessa geometria del DEM. Per i prodotti interferometrici si è fatto uso di SPINUA (Stable Point INterferometry over Un-urbanised Areas), software progettato dal gruppo di telerilevamento del Dipartimento di Fisica di Bari. Il DEM e la mappa di coerenza, inizialmente riferiti su griglia sparsa, sono stati riportati su griglia regolare per mezzo di procedure Matlab. Matlab è stato utilizzato anche per l’analisi di qualità sui prodotti che sono stati testati in forma globale, facendo uso di DEM di riferimento per una analisi sull’accuratezza della quota in funzione delle pendenze e in forma locale con una analisi fatta con i PS sull’accuratezza della quota. Le immagini COSMO-SkyMed usate per questo lavoro sono stati forniti da ASI nell’ambito dei seguenti progetti: (i) processing interferometrico e interferometrico differenziale: progetto ID-1467 ""Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation"" - ASI Contract I/063/09/0; (ii) processing radargrammetrico: richieste appositamente la tesi di dottorato."
Desidero ringraziare tutti coloro che mi hanno aiutato a svolgere questo lavoro. Innanzi tutto il mio grazie va ai tutori: la Prof.ssa Maria Teresa Chiaradia e il Dott. Francesco Nirchio dell’Agenzia Spaziale Italiana, per il loro prezioso sostegno e la disponibilità mostrata. Ringrazio il gruppo di Telerilevamento di Bari, in particolare il Prof. Luciano Guerriero, il Dott. Davide Nitti e l’Ing. Raffaele Nutricato per aver fornito lo stack di immagini interferometriche e per il supporto nel trattamento dei dati interferometrici. Un sentito ringraziamento va al CNR/ISSIA per l’ospitalità nei laboratori e per aver messo a disposizione le risorse finalizzate al trattamento dei dati radargrammetrici; in particolare sono grato al Dott. Alberto Refice, al Dott. Fabio Bovenga e al Dott. Guido Pasquariello, per gli utili consigli, i fruttuosi confronti e le idee che ne sono scaturite. In ultimo ma non ultimi desidero esprimere la mia riconoscenza a Giovanni Preziosa e Antonio Mongelli per l’amicizia e la disponibilità a sostenere e partecipare a questa mia avventura. A mia moglie e ai miei genitori per l’inesauribile pazienza.
Peer-Reviewed Journal Articles
[Nit.Sensors2015] D. O. Nitti, F. Bovenga, M. T. Chiaradia, M. Greco and G. Pinelli, "Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation", Sensors 2015, vol. 15, pp. 18334-18359; EISSN 1424-8220. Scopus: 2-s2.0-84938267144. doi:10.3390/s150818334. IF: 2.80 (Year: 2015 - Source: https://goo.gl/iI4kfI)
This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.
The authors acknowledge the support of the SARINA project A-0932-RT-GC, which is coordinated by the European Defence Agency (EDA) and partially funded by 10 contributing Members (Cyprus, France, Germany, Greece, Hungary, Italy, Norway, Poland, Slovakia, Slovenia and Spain) in the framework of the Joint Investment Programme on Innovative Concepts and Emerging Technologies (JIP-ICET).
Book Chapters
[Was.IAEG2014] J. Wasowski, F. Bovenga, A. Refice, D. O. Nitti, R. Nutricato, "High Resolution PSI For Mapping Ground Deformations And Infrastructure Instability". Proceedings of the IAEG XII congress, Turin, Italy, 15-19 September 2014. In Book: G. Lollino et al. (eds.), Engineering Geology for Society and Territory – Volume 2, Springer International Publishing Switzerland 2015. ISBN:978-3-319-09057-3; 978-3-319-09056-6. Scopus: 2-s2.0-84944618574. WOS:000358988100063. DOI: 10.1007/978-3-319-09057-3_63.
Persistent scatterers interferometry (PSI) techniques based on space-borne radar data can provide thousands km2 coverage and precise (mm resolution), spatially dense measurements (from hundreds to over thousands points/km2) on ground surface deformations and infrastructure instability. Furthermore, the practical applicability of PSI is now improved thanks to the increased data availability from ra-dar satellites and the better capabilities of the new space radar sensors (Cosmo-SkyMed, TerraSAR-X) in terms of resolution (from ~3 to 1 m) and revisit time (from 11 to 4 days). Here we compare results from medium and high resolution PSI investigations of subsidence, slope and associated infrastructure instability in two areas with different geo-environmental characteristics in order to illustrate i) the potential in providing valuable site-specific information, ii) the advantages in using high resolution radar data. We also focus on significant technical and interpretation issues in PSI applications and offer specific user guidelines, with emphasis on the benefits resulting from the exploitation of new generation radar sensors.
ERS-1/2 and TSX data over Wieliczka provided, respectively, by the European Space Agency (ESA) under ALOS ADEN 3595 project and by DLR under TerraSAR-X General AO Project ID MTH0432. CSK images over Haiti provided by the Italian Space Agency (ASI) in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS) of Haiti and the Department of Physics (DIF) of the University of Bari, Italy. CSK images over Calabria region provided by ASI in the framework of the project “Landslide Monitoring and Mapping System - CAR-SLIDE” (PON 01 00536). ENVISAT and TSX data over Pietramontecorvino provided, respectively, by ESA under CAT-1 project ID 2653 and by DLR under TerraSAR-X General AO Project ID MTH0432. Optical images provided by GoogleEarthTM.
International Conference Proceedings
[Gue.EESMS2015] A. Guerriero, F. Giuliani, D. O. Nitti, "Crowdsourcing And Mobile Device For Wide Areas Monitoring", Proceedings of the 2015 IEEE Workshop on Environmental, Energy and Structural Monitoring Systems, 9-10 July 2015, Trento, Italy. Electronic ISBN: 978-1-4799-8215-8. CD-ROM ISBN: 978-1-4799-8214-1. Scopus: 2-s2.0-84950983172. DOI: 10.1109/EESMS.2015.7175847
This paper presents the architecture of an extended areas monitoring system based on crowdsourcing and mobile devices. In particular areas (i.e. very large historical site) it can be difficult or impossible to install fixed cameras due mainly to the huge number of candidate points of interest (POI) to monitoring or to the significant impact on site (i.e. cameras or other sensors could be too invasive towards historic walls or ancient materials). For these sites we propose a system based on a distribute architecture, a server that runs change detection algorithms and clients that run on visitors’ smartphones and assists the acquisition of new pictures comparable to reference photos of the monitored areas. Server contains geo-referenced images of the POI and can automatically add new images of the same POI under partly different observation conditions (like angle of view or light or shadows distribution). The client section, the app on the mobile devices, shows all the POI in the neighboring area of the user, provides a map to reach a selected POI, compares in real time the reference photo of the POI provided by the server with the live view of the smartphone camera and supplies the user directions to obtain the correct overlap of the images.
[Gue.IGARSS2015] A. Guerriero, V. W. Anelli, A. Pagliara, R. Nutricato, D. O. Nitti, "Efficient implementation of InSAR time-consuming algorithm kernels on GPU environment", Proceedings of 2015 IGARSS - International Geoscience and Remote Sensing Symposium, Milano, Italia, 26-31 July 2015 . Electronic ISBN: 978-1-4799-7929-5. USB ISBN: 978-1-4799-7928-8. Print ISSN: 2153-6996. Electronic ISSN: 2153-7003. Scopus: 2-s2.0-84962599944. WOS:000371696704087. DOI: 10.1109/IGARSS.2015.7326768
Satellite remote sensing radar technologies provide powerful tools for geohazard monitoring and risk management at synoptic scale. In particular, advanced Multi-Temporal SAR Interferometric algorithms are capable to detect ground deformations and structural instabilities with millimetric precision, but impose strong requirements in terms of hardware re-sources. Recent advances in GPU computing and programming hold promise for time efficient implementation of imaging algorithms, thus enhancing the development of advanced Emergency Management Services based on Earth Observation technologies. In this study, a preliminary assessment of the potentials of GPU processing is carried out, by comparing CPU (single- and multi-thread) and GPU implementations of InSAR time-consuming algorithm kernels. In particular, it is focused on the fine coregistration of SAR interferometric pairs, a crucial step in the interferogram generation process. Experimental results are discussed.
ASAR images made freely available by ESA (dataset SAR Italy EQ April 2009). The authors thank Ferrara Fabio, Lippolis Paola and Saponaro Pierpaolo for their contribution on the OpenMP implementation.
[Nit.SPIE2015] D. O. Nitti, R. Nutricato, R. Lorusso, N. Lombardi, F. Bovenga, M. F. Bruno, M. T. Chiaradia, G. Milillo, "On the geolocation accuracy of COSMO-SkyMed products", Proc. SPIE 9642, SAR Image Analysis, Modeling, and Techniques XV, 96420D (15 October 2015); ISBN: 9781628418521. Scopus: 2-s2.0-84961653912. DOI: 10.1117/12.2196870
Many factors impact on the geolocation accuracy of Synthetic Aperture Radar (SAR) products. The improper Atmospheric Path Delay (APD), orbital errors and timing inaccuracies hinder sub-pixel geolocation accuracy, in particular for radar images acquired by the high resolution X-band side-looking SAR satellite constellations, TerraSAR-X (TSX) and COSMO-SkyMED (CSK). Many scientific studies in the recent literature have demonstrated the suitability of TSX data for sub-decimetre level ranging accuracy without the use of ground control points (GCP, provided APD is properly estimated and corrected for. This is due to the high degree of orbital accuracy of the TSX satellites (the so-called science orbit is in an accuracy range of few centimetres and its very precise radar beam tracing. On the contrary, no definitive results are reported yet in the scientific literature, concerning the best performances achievable by the CSK constellation in terms of geolocation accuracy. Preliminary studies have shown that sub-metric geolocation accuracies are hardly achievable with CSK data, and that APD compensation leads unexpectedly to a worsening of the results (with geolocation errors amounting even to several meters along the slant range direction). Two possible explanations were suggested: (1) a nominal, undocumented APD correction is incorporated into the CSK delivered timing annotations during sampling window start time (SWST) bias calibration, or (2) no APD correction has been implemented in the CSK delivered data, but the annotated range SWST bias is incorrect by several meters (implying the need for re-calibration). These results are in line with the conclusions of other independent studies. The aim of the present work is to further investigate the origin of the geolocation error sources in CSK products. The area surrounding Carlantino town in Daunia region (Southern Italy), has been selected for this study, thanks to the availability of six trihedral corner reflectors (CR) recently installed in the western slope, facing the Occhito lake. The geolocation of CR phase centers is surveyed with cm-level accuracy using differential GPS. A consistent number of CSK HIMAGE stripmap and enhanced spotlight data takes is available over the area of interest. The experimental analysis includes the evaluation of the geolocation accuracy of both SCS and GTC products. Concerning SCS data, the performances of the official ASI processors are compared to those achievable by alternative promising focusing algorithms, for both stripmap and spotlight modes. APD compensation is performed by using the Regional Atmospheric Modelling System (RAMS), a Numerical Weather Prediction model already reliably used for this purpose in previous. The analysis is also extended to the cross-comparison of I-CUGS GTC products with those generated by internal geocoding tools.
[Nut.IGARSS2015] R. Nutricato, D. O. Nitti, F. Bovenga, A. Refice, J. Wasowski, M. T. Chiaradia, G. Milillo, "COSMO-SkyMED multi-temporal SAR interferometry over Liguria region for environmental monitoring and risk management", Proceedings of 2015 IGARSS - International Geoscience and Remote Sensing Symposium, Milano, Italia, 26-31 July 2015 . Electronic ISBN: 978-1-4799-7929-5. USB ISBN: 978-1-4799-7928-8. Print ISSN: 2153-6996. Electronic ISSN: 2153-7003. Scopus: 2-s2.0-84962529299. WOS:000371696701131. DOI: 10.1109/IGARSS.2015.7326040
Thanks to the technological maturity as well as to the wide availability of SAR data, Multi-temporal SAR Interferometry (MTInSAR) can be used to support systems devoted to environmental monitoring and risk management. In particular, high resolution X-band MTInSAR applications are also suitable for monitoring single man-made structures (buildings, bridges, railways and highways). The paper presents examples concerning the application of MTInSAR techniques and COSMO-SkyMed constellation for instability monitoring of infrastructures and, in particular, harbor docks and railways.
Work supported by the projects “CAR-SLIDE -Mapping and monitoring system for landslides forecast” (PON R&C 2007-2013) and “ADF - Archiving Data Fusion” (Second ASI Call dedicated to SMEs), and in the framework of the collaboration between Geophysical Applications Processing Ltd and the Physics Department of Bari with CIDOT (Centro di Eccellenza di Interpretazione Dati di Osservazione della Terra - ASI Matera). CSK products processed under a license of ASI "Original COSMOSkyMed Product - Agenzia Spaziale Italiana - (2013-2014). All rights reserved".
[Tij.IGARSS2015] K. Tijani, M. T. Chiaradia, A. Morea, R. Nutricato, L. Guerriero, G.Pasquariello, "Fishing forecasting system in Adriatic sea - a model approach based on a normalized scalar product of the SST gradient and CHL gradient vectors". Proceedings of 2015 IGARSS - International Geoscience and Remote Sensing Symposium, Milano, Italia, 26-31 July 2015 . Electronic ISBN: 978-1-4799-7929-5. USB ISBN: 978-1-4799-7928-8. Print ISSN: 2153-6996. Electronic ISSN: 2153-7003. WOS:000371696702089. Scopus: 2-s2.0-84962571879.DOI: 10.1109/IGARSS.2015.7326256
By mapping the concentration of chlorophyll-a (CHL) and the temperature of the sea surface (SST), satellite images reveal the complex dynamics of marine waters and prove to be a very powerful tool when used to detect potential fishing areas, significantly reducing the time of the search, the fuel consumption and the human effort, and simultaneously increasing the CPUE (catch per unit effort). In the present work, various techniques of multi-sensor, multi-resolution and multi-temporal data fusion are applied to multi-spectral satellite image data of MODIS-AQUA, MODIS-TERRA and VIIRS sensors, in order to detect "fronts" of chlorophyll concentration and temperature on the sea surface. According to the physical model of the phenomena, these fronts are generated by the upwelling of cold waters rich of nutrients (phytoplankton) which correspond to areas with a high concentration of pelagic fish and are characterized by high values of local gradients of SST and CHL with anti-parallel orientation. An automatic procedure has been developed to calibrate and validate the production in near-real time of daily maps of expected good fishing grounds to be provided to the FEDERPESCA fleet. The same procedure could be optimized also for other seas.
Work funded by Apulia Region, in the framework of the project "Sustainable Fishery" (FEP 2007-2013 – Measure3.1).
[Was.ARS2015] J. WASOWSKI, F. BOVENGA, R. NUTRICATO, D. O. NITTI, M. T. CHIARADIA, S. KUCAJ and B. STRATI, "High resolution satellite multi-temporal interferometry for detecting and monitoring landslide and subsidence hazards", ARS 2015 - 10th Regional Asian Conference of IAEG in Kyoto, 26-27 September 2015, Japan, Kyoto. URL: http://www.jseg.or.jp/2015ARC/data/PaperofInvited/Wasowski_et_al.pdf
With the increasing number of radar satellites and improved data processing tools, multi-temporal interferometry (MTI) can considerably enhance our capabilities of monitoring landslide and subsidence hazards. MTI provides long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), combined with high spatial resolution (up to 1-3 m) and possibility of multi-scale (regional to site-specific) investigations using the same series of radar images. To highlight the great potential of high resolution MTI we discuss application examples from two seismically active regions prone to land instability: i) Albania, including the large plain area occupied by the city of Tirana and nearby scarcely populated mountains, and ii) Haiti, including the Port-au-Prince metropolitan area, with coastal and mountain zones destabilized by the 2010 Mw 7.0 earthquake. It is shown that MTI can provide very useful results in a wide range of geomorphic, climatic and vegetation environments.
[Was.Geomorphometry2015] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, M. T. Chiaradia, L. Guerriero, "High resolution satellite SAR multi-temporal interferometry for regional scale detection of landslide and subsidence hazards", Proceedings of Geomorphometry 2015, Poznan, Poland, June 22-26, 2015. In: Geomorphometry for Geosciences, Jasiewicz J., Zwolinski Zb., Mitasova H., Hengl T. (eds), pp. 181-184, 2015. Publisher: Publisher Bogucki Wydawnictwo Naukowe, Adam Mickiewicz University in Poznan - Institute of Geoecology and Geoinformation, Poznan, Poland. ISBN: 978-83-7986-059-3. URL: http://geomorphometry.org/system/files/Wasowski2015geomorphometry.pdf
Among a number of advanced satellite-based remote sensing techniques, synthetic aperture radar (SAR) multi-temporal interferometry (MTI) appears the most promising for fostering new opportunities in landslide and subsidence hazards detection and assessment. MTI is attractive to those concerned with terrain instability hazards because it can provide very precise quantitative information on slow displacements of the ground surface over huge areas with limited vegetation cover. Although MTI is a mature technique, we are only beginning to realize the benefits of the high-resolution imagery that is currently acquired by the new generation radar satellites (e.g., COSMO-SkyMed, TerraSAR-X). In this work we demonstrate the great potential of high resolution MTI for regular, wide-area detection of ground instability hazards by presenting results from two regions characterized by different geomorphic, climatic and vegetation conditions: densely populated metropolitan area of Port-au-Prince (Haiti), with the coastal areas and local slopes destabilized by the 2010 Mw 7.0 earthquake, and the remote high mountain region of Southern Gansu Province (China) prone to large slope failures. The interpretation and widespread exploitation of high spatio-temporal resolution MTI results can be facilitated by visualizing the scientific data using Google Earth TM tools or other web-based applications.
The Italian Spatial Agency (ASI) provided CSK imagery of China (AO Project ID 1820) and of Haiti (collaboration between the Centre National dell'Information Géo-Spatiale -CNIGS, Haiti and the Department of Physics of the Politecnico di Bari, Italy). We also thank three reviewers for helpful comments.
[WAS.EGNM2015] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti and M. T. Chiaradia, "Advanced Satellite Interferometry for Monitoring Road and Railway Infrastructure in Landslide-Prone Areas", Proceedings of the International Conference on Engineering Geology in New Millennium, At Indian Institute of Technology, New Delhi, India. In Volume: Special Publication Journal of Engineering Geology, October 2015, pp. 1349-1359. ISSN: 0970-5317.
Roads and railways are exposed to instability and damage in landslide-prone areas. While conventional ground-based techniques are too costly for regular, wide-area monitoring of unstable slopes and transpor-tation infrastructure, satellite multi-temporal interferometry (MTI) can now effectively assist in hazard assessment thanks to the improved temporal (days-weeks) and spatial resolutions (1-3 m) of the new satellite radar sensors. The most important strengths of MTI are i) wide-area coverage (up to tens of thou-sands km2) combined with high spatial resolution (meters) and precision of ground surface displacement measurements (mm-cm) and ii) regular, long-term (years) data acquisition with short revisit times (weeks to days) and the availability of long time series of data (since 1992). These strengths offer flexibility to MTI applications such as the possibility of using the same series of images for various scale hazard as-sessments (from regional to local). Importantly, engineering structure response to ground motion can be investigated at high spatial-temporal resolutions over large areas by using the new radar satellites (e.g., the Italian constellation COSMO-SkyMed; the German TerraSAR-X). To highlight the potential of MTI for monitoring transportation infrastructure stability in landslide-prone areas we present regional to local scale case study examples of MTI applications in Italy.
[Was.SMPR2015] Wasowski, J., Bovenga, F., Nutricato, R., Nitti, D. O., and Chiaradia, M. T., "APPLICATIONS OF MEDIUM C-BAND AND HIGH RESOLUTION X-BAND MULTITEMPORAL INTERFEROMETRY IN LANDSLIDE INVESTIGATIONS", Proceedings of SMPR 2015 (Sensors and Models in Photogrammetry and Remote Sensing), ISPRS, 3rd International Conference on Geo-information Modeling and Environmental Monitoring, 23–25 November 2015, Kish Island, Iran. In: Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XL-1/W5, pp. 737-743, 2015. ISSN: 2194-9034. WOS:000380618200123. Scopus: 2-s2.0-84974533495. DOI:10.5194/isprsarchives-XL-1-W5-737-2015.
With the increasing quantity and quality of the imagery available from a growing number of SAR satellites and the improved processing algorithms, multi-temporal interferometry (MTI) is expected to be commonly applied in landslide studies. MTI can now provide long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), at medium (~20 m) to high (up to 1-3 m) spatial resolutions, combined with the possibility of multi-scale (regional to local) investigations, using the same series of radar images. We focus on the benefits as well as challenges of multi-sensor and multi-scale investigations by discussing MTI results regarding two landslide prone regions with distinctly different topographic, climatic and vegetation conditions (mountains in Central Albania and Southern Gansu, China), for which C-band (ERS or ENVISAT) and X-band COSMO-SkyMed (CSK) imagery was available (all in Stripmap descending mode). In both cases X-band MTI outperformed C-band MTI by providing more valuable information for the regional to local scale detection of slope deformations and landslide hazard assessment. This is related to the better spatial-temporal resolutions and more suitable incidence angles (40°-30° versus 23°) of CSK data While the use of medium resolution imagery may be appropriate and more cost-effective in reconnaissance or regional scale investigations, high resolution data could be preferentially exploited when focusing on urbanized landslides or potentially unstable slopes in urban/peri-urban areas, and slopes traversed by lifelines and other engineering structures.
[Was.EGU2015] J. Wasowski, R. Nutricato, D. O. Nitti, F. Bovenga, M. T. Chiaradia, B. E. Piard and P. Mondesir, "Using high resolution satellite multi-temporal interferometry for landslide hazard detection in tropical environments: the case of Haiti". Abstracts proceedings EGU 2015, Vienna, Austria, 12 - 17 April 2015. Abstract ID-No: EGU2015-13957. Vol. 17, eISSN: 1607-7962.
Synthetic aperture radar (SAR) multi-temporal interferometry (MTI) is one of the most promising satellite-based remote sensing techniques for fostering new opportunities in landslide hazard detection and assessment. MTI is attractive because it can provide very precise quantitative information on slow slope displacements of the ground surface over huge areas with limited vegetation cover. Although MTI is a mature technique, we are only beginning to realize the benefits of the high-resolution imagery that is currently acquired by the new generation radar satellites (e.g., COSMO-SkyMed, TerraSAR-X). In this work we demonstrate the potential of high resolution X-band MTI for wide-area detection of slope instability hazards even in tropical environments that are typically very harsh (eg. coherence loss) for differential interferometry applications. This is done by presenting an example from the island of Haiti, a tropical region characterized by dense and rapidly growing vegetation, as well as by significant climatic variability (two rainy seasons) with intense precipitation events. Despite the unfavorable setting, MTI processing of nearly 100 COSMO-SkyMed (CSK) mages (2011-2013) resulted in the identification of numerous radar targets even in some rural (inhabited) areas thanks to the high resolution (3 m) of CSK radar imagery, the adoption of a patch wise processing SPINUA approach and the presence of many man-made structures dispersed in heavily vegetated terrain. In particular, the density of the targets resulted suitable for the detection of some deep-seated and shallower landslides, as well as localized, very slow slope deformations. The interpretation and widespread exploitation of high resolution MTI data was facilitated by Google EarthTM tools with the associated high resolution optical imagery. Furthermore, our reconnaissance in situ checks confirmed that MTI results provided useful information on landslides and marginally stable slopes that can represent a considerable hazard to the local population and infrastructure. The case of Haiti suggests that in the future MTI applications can become increasingly more important in cases where little or no conventional monitoring is feasible because of limited funds.
The Italian Spatial Agency (ASI) provided CSK imagery of Haiti in the framework of a scientific collaboration between the Centre National de l’Information Géo-Spatiale (CNIGS), Haiti and the Department of Physics of the Politecnico di Bari, Italy. We also thank Aldo Giovacchini (Consorzio ITA) and Luciano Guerriero for their help with the project.
[Was.Osuwiska2015] J. Wasowski, F. Bovenga, R. Nutricato, D.O. Nitti, M.T. Chiaradia, "Zastosowanie interferometrii satelitarnej o wysokiej rozdzielczosci do monitorowania infrastruktury drogowej i kolejowej w obszarach osuwiskowych". Konferencja Osuwiskowa 2015, Wieliczce, Polska, 19-22 maja 2015.
[Was.GeoBerlin2015] J. Wasowski and F. Bovenga, "Toward better exploitation of satellite multi-temporal interferometry in landslide hazard research". In Wagner, J.; Elger, K. [Eds.] (2014) GeoBerlin2015 - Dynamic Earth from Alfred Wegener to today and beyond - Abstracts. Annual Meeting of DGGV and DMG, 4-7 October 2015. DOI: http://doi.org/10.2312/GFZ.LIS.2015.003
In situ investigations and monitoring of areas prone to landslides are expensive and limited in terms of spatial and temporal coverage. Therefore, the use of complementary cost-effective remote sensing approaches to slope hazard detection and assessment is an important issue. We solicit a widespread application of satellite multi-temporal interferometry (MTI), an advanced technique that can enhance our capabilities of detecting and monitoring slope hazards. MTI provides long-term (years), regular (weekly-monthly), precise (mm) measurements of ground displacements over large areas (thousands of km2), combined with high spatial resolution (up to 1-3 m) and a possibility of multi-scale (regional to site-specific) investigations using the same series of radar images. Further, the initial reconnaissance approaches relying on medium resolution MTI (e.g. ENVISAT, RADARSAT) can now be suitably integrated with high resolution MTI relying on the new generation radar sensors (e.g. COSMO-SkyMed, TerraSAR-X), thereby providing most valuable information for the spatial and temporal analyses of slope deformation and landslide activity. To highlight the great potential of MTI we present application examples from two seismically active regions prone to land instability. We also stress that MTI results have yet to be fully explored, in particular those based on high spatio-temporal resolution data. Some of the landslide research and application areas that may particularly benefit from MTI include: - Long-term behavior and climatic controls of large, long-lived very slow deep landslides and deep-seated gravitational slope deformations - Post-earthquake landslide activity and evolution of slopes - Early detection and warning of slope instability hazards via long-term monitoring.
COSMO-SkyMed and TSX data provided, respectively, by the Italian Spatial Agency (ASI) within the COSMO-SkyMed AO Project ID 1820, and by DLR under TerraSAR-X General AO Project ID MTH0432.
[Was.ReSyLAB2015] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, M. T. Chiaradia, "Satellite interferometry for landslide detection in the peri-Adriatic area", Conference: 2nd Regional Symposium on Landslides in the Adriatic-Balkan Region, Belgrade, Serbia, 14-16 May, 2015. Volume: Abolmasov, B. (2015): 2nd Regional Syposium on Landslides in the Adriatic-Balkan Region - Abstracts Proceedings, University of Belgrade, Faculty of Mining and Geology, Belgrade, Serbia, ISBN 978-86-7352-324-8. URL: http://resylab2015.rgf.rs/Predavanja/Invited_Lecturers/INVITED01_Wasowski.pdf
Advanced multi-temporal interferometry (MTI) techniques are being increasingly used in landslide assessment, as they can provide precise (mm-cm resolution) measurements of very slow ground surface displacements for huge areas with limited vegetation cover. We illustrate the potential of high resolution MTI for wide-area and local-scale detection of slope and associated infrastructure instability hazards in the peri-Adriatic region. This is done by presenting MTI applications to two landslide-prone mountainous areas characterized by different geomorphic, climatic and vegetation conditions, and hence by variable density and distribution of potential radar targets: the eastern-most part of the Southern Apennines and the mountains in central Albania. The results demonstrate that even in such scarcely urbanized areas MTI can provide valuable information on the presence of slope movements that locally affect small human settlements and road network. The gaps in satellite-derived information, especially evident in the more forested Albanian mountains, suggest that MTI could be most profitably exploited in the reconnaissance stage of a slope hazard assessment, to be followed by more detailed investigation and monitoring of sites at risk.
We thank the Italian (ASI) and German (DLR) space agencies for providing radar satellite imagery. We benefited from the collaboration with Dr. Spartak Kucaj of the Faculty of Geology & Mining Tirana, Albania and from the CSK imagery acquired within the project "Studio su instabilità del terreno sull’area di Tirana (Albania)”.
Other poster/slideshow presentations
[Urb.OpenGeoData] V. Urbano, A. Morea, K. Tijani, D. O. Nitti, R. Nutricato, "Open Data satellitari e Sentinel-1: servizi di osservazione della Terra su Cloud", 3° Conferenza OpenGeoData Italia 2015, Sessione "Applicazioni per la pubblicazione ed il riuso dei dati geografici aperti", Roma, 19 Febbraio 2015
[Was.Fringe2015] J. Wasowski, F. Bovenga, R. Nutricato, D. O. Nitti, M. T. Chiaradia, "PSI for landslide hazard assessment and monitoring: current issues, underexploited and future application opportunities", Fringe 2015 Workshop Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR Workshop, Frascati (Rome), Italy, 23-27 March 2015. URL: http://seom.esa.int/fringe2015/page_session24.php#39p
We discuss current and future opportunities and challenges of PSI applications to slope hazard assessment and monitoring with reference to the recent and upcoming radar satellite launches and the most recent literature (e.g. Bianchini et al., 2014; Wasowski and Bovenga, 2014a,b). In particular, it is envisioned that by offering regular globe-scale coverage, improved temporal resolution (weekly or better) and freely available imagery, new radar satellite missions such as the ESA’s Sentinel-1 will guarantee an ever increasing and more efficient use of PSI in landslide investigations. These background missions are necessary for long-term, systematic mapping of unstable or potentially unstable slopes and regional scale assessment of landslide processes. The initial wide-area (reconnaissance) approaches relying on medium resolution PSI (e.g. ENVISAT, Sentinel-1) can be suitably integrated with high resolution PSI relying on the new radar sensors (e.g. COSMO-SkyMed, TerraSAR-X, RADARSAT-2), thereby providing most valuable information for the spatial and temporal analyses of slope deformation and a sound basis for derived products ranging from individual landslide monitoring to regional hazard identification. The benefits of multi-sensor and multi-scale investigations (from regional to site-specific) are discussed by presenting PSI results concerning two regions (Central Europe and Western China) characterized by distinctly different topographic, climatic and vegetation conditions. It is shown that, with respect to the medium resolution PSI products (based on ERS and ENVISAT imagery in our case studies), the PSI products derived from high resolution imagery (Stripmap COSMO-SkyMed and TerraSAR-X) may not always lead to a significant improvement in terms of detection of unstable slopes or kinematic characterization of active landslides. Therefore, for its most effective use PSI will have to be tailored to the specific region/site conditions, landslide types, depending on the primary objectives of the investigation. For example, in case of critical facilities at risk such as dams or bridges, of urbanized landslides or potentially unstable slopes in urban/peri-urban areas, as well as of slopes traversed by critical lifelines and engineering structures, the cost of acquiring and processing high resolution radar data can easily be justified. Conversely, in wide-area regional investigations, the use of medium resolution imagery will be more appropriate and the most cost-effective. In general, thanks to the improving temporal and spatial resolutions of new generation radar sensors, significant breakthroughs are expected in detailed slope instability process modelling (e.g. kinematic and geotechnical models), as well as in the understanding of spatial and temporal patterns of landslide movement/activity and their relationships to causative or triggering factors (e.g. precipitation, seismic loading). The capability to provide, at regular intervals, long-term ground surface deformation trends offers an unprecedented opportunity for early detection and warning of potential slope instabilities, but further research is needed with focus on the integration of data from PSI and ground-based geotechnical monitoring. We consider this as one of the top applied research priorities. Finally, we stress that PSI-derived results have yet to be fully explored, in particular those based on high spatio-temporal resolution data. Some of the landslide research and application areas that may benefit more from PSI include: (i) Long-term behavior and climatic controls of very slow deeper landslides and deep-seated gravitational slope deformations; (ii) Numerical modeling of very slow persistent landslides and long term evolution of slopes; (iii) Post-earthquake landslide activity and evolution of slopes; (iv) Non-linear kinematics of landslides, maximum velocities and accumulated displacements.
ENVISAT, COSMO-SkyMed and TSX data were provided, respectively, by ESA under CAT-1 project ID 2653, by the Italian Spatial Agency (ASI) within the COSMO-SkyMed AO Project ID 1820, and by DLR under TerraSAR-X General AO Project ID MTH0432.
[Nut.Fringe2015] Nutricato R., Nitti D. O., Bovenga F., Refice A., Wasowski J., Chiaradia M. T., Milillo G., "Exploitation of Multi-Temporal SAR Interferometry for systems devoted to Environmental Monitoring and Risk Management", Fringe 2015 Workshop Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR Workshop, Frascati (Rome), Italy, 23-27 March 2015. URL: http://seom.esa.int/fringe2015/page_session28.php#82p
Multi-temporal SAR Interferometry (MTInSAR) techniques allow detecting and monitoring millimetric displacements occurring on selected point targets exhibiting coherent radar backscattering properties. Successful applications to different geophysical phenomena have been already demonstrated in literature. During the last several years new application opportunities have emerged thanks to the greater data availability offered by recent launches of radar satellites, and the improved capabilities of the new space radar sensors in terms of both resolution and revisit time. Currently, different space-borne SAR data in L-,C- and X-band are available for InSAR applications. The archived data from the European Space Agency (ESA) missions ERS-1/2 and ENVISAT (ENV) acquired in C-band (about 5 cm of wavelength), at medium resolution (5x20 m2) from 1992 to 2011 make available a large number (more than 40) of images covering more then 10 years with a minimum revisit time of 35 days, which allows performing ground instability analysis back in time almost all over the Earth. ESA Sentilnel-1 constellation will provide the continuity of the C-band SAR operational applications from October 2014. Thanks to the technological maturity as well as to the wide availability of SAR data, MTInSAR can be used to support systems devoted to environmental monitoring and risk management. This work present results obtained in the framework of two projects: the CAR-SLIDE (Mapping and monitoring system for landslides forecast) project which is funded by MIUR (PON R&C 2007-2013) and ADF (Archiving Data Fusion) project, funded by the Italian Space Agency (Second ASI Call dedicated to SMEs). CAR-SLIDE is aimed at implementing an advanced diagnostic system capable to warn of and monitor landslide events along railway networks, by integrating in situ data detected from on board sophisticated innovative measuring systems, with Earth Observation (EO) techniques. In particular SAR interferometry is used to monitor landslide events. The CAR-SLIDE system is structured in a modular way and mainly consists of the following three subsystems (S/S): (1) railway infrastructure monitoring S/S (based on video inspection sensors, georadars, vibration measurement systems and track geometry measuring devices) ; (2) Environmental Monitoring system (based on satellite SAR and optical data, and weather forecast provided by prognostic non-hydrostatic numerical mesoscale models); (3) Support Decision System (SSD). All measurements provided by the respective monitoring systems are integrated into the SSD, with the aim of improving the railway transport security management, by extending the concept of “black-box for alarm generation” to the actual idea of “telemetry for security management”. The goal of the ADF project is to design an innovative system for EO data acquisition, processing, fusion and archiving to support public institutions and private companies involved in emergency management, territorial planning and precise farming. The system has the capability to interface with many EO (SAR and optical) and traditional data sources and archives, thus enabling their selection and processing on demand, and to perform data fusion of EO data with ancillary data (INSPIRE, OpenStreetMap, etc.), with a high level of automatism. Concerning emergency management, data fusion techniques of SAR and optical data, together with land cover maps and digital terrain models are used to provide a priori estimations of Persistent Scatterers density along different line-of-sights, look sides and pass directions. We presents results obtained by processing COSMO-SkyMed satellite data acquired over Calabria region (Southern Italy) and Liguria region (Northern Italy). The first test case shows interesting results concerning the Calabria's Tyrrhenian railway line, classified as fundamental line by the Italian Rail Network and belonging to the Trans-European Transport Network. Moreover, it provides another interesting example of infrastructure monitoring concerning the “Giambarelli” viaduct along the A3 highway close to the Barritteri town. The second example consists in a retrospective analysis on the detection of precursory signals related to the landslide which occurred on January 2014 close to the town of Marina di Andora. The landslide caused the derailment of a train and the interruption of the railway line connecting north-western Italy to France. We show that a cluster of moving targets coincides with the structures (buildings and terraces) affected by the 2014 landslide. The analysis of the MTI time series further shows that the targets had been moving since 2009, and thus could have provided a forewarning signal about ongoing slope or engineering structure instability. Further examples, concerning the suitability of MTInSAR techniques and high-resolution SAR sensors for man-made structures stability over the Genoa metropolitan and surrounding areas, are also presented and discussed.
Work supported by the projects “Landslide Monitoring and Mapping System - CAR-SLIDE” (PON 01 00536) and “ADF - Archiving Data Fusion” (Second ASI Call dedicated to SMEs). CSK data are provided by ASI (Agenzia Spaziale Italiana) in the framework of CAR-SLIDE and ADF projects and the collaboration between Geophysical Applications Processing - GAP srl and CIDOT (Centro di eccellenza di Interpretazione Dati di Osservazione della Terra – ASI Matera).
[Abba.GRSG2015] C. Abbattista, I. Epicoco, F. Macchia, Francesca Mele, D. O. Nitti, R. Nutricato, "GPU4EO challenge 2015: boosting SAR interferometry", Challenges in Geological Remote Sensing, 9-11 December 2015, ESA ESRIN, Frascati, Italy. URL: https://www.grsg.org.uk/abstracts/gpu4eo-challenge-2015-boosting-sar-interferometry/
Recent advances in GPU computing and programming hold promise for time efficient implementation of imaging algorithms, thus enhancing the development of advanced Emergency Management Services based on Earth Observation technologies. In the framework of the RIESCO project, Planetek Italia Srl has promoted the GPU4EO Challenge 2015, whose goal was to stimulate the intensive use of GPUs in the field of image processing and more specifically in the field of remote sensing applications, in order to enhance the synergy between research and business. In particular, Synthetic Aperture Radar (SAR) Differential Interferometry is a powerful and consolidated technique for ground displacements detection and geohazard monitoring, but impose strong requirements in terms of hardware resources. To this end, the Delft Object-oriented Radar Interferometric Software (DORIS) was selected as target application. This open source tool, developed by the DEOS Institute of the Delft University of Technology, is specific for the interferometric processing of satellite SAR images and is composed of a number of computing processes to be optimized and ported to GPU platforms, in order to reduce the overall execution time. GPU4EO has been a sprint initiative, from April to mid-June 2015, which involved research teams coming from different Italian universities. A reference hardware platform was provided to all the participants by the ReCaS data center, based on NVIDIA K40 board, for testing the developments and assessing the performance achieved. In this presentation, the most effective results achieved by the winner team, from University of Salento, will be presented. The main issues have been the data dependency within loops, the optimal use of device memory hierarchy, the isolation of the I/O operations and the use of existent optimized numerical library for GPU like cuFFT. The results achieved within the challenge timeframe have been very encouraging, reaching more than 5x of performance improvement.
[Chi.GRSG2015] M. T. Chiaradia, A. Morea, K. Tijani, L. Guerriero, R. Nutricato, D. O. Nitti, G. Pasquariello, F. Bovenga, A. Refice, "Preliminary Analysis of Sentinel-1 IW data for Geohazard Monitoring and Mapping", Challenges in Geological Remote Sensing, 9-11 December 2015, ESA ESRIN, Frascati, Italy.
SENTINEL-1 (S1) mission has been developed by ESA for the specific priorities of the Copernicus programme. S1 is a constellation of two satellites carrying a C-Band Synthetic Aperture Radar (SAR), designed to provide enhanced revisit frequency, continuous acquisition plan, large-scale coverage (thanks to the innovative IW – Interferometric Wide swath acquisition mode, capable to cover swaths on ground up to 250 km wide), timeliness and reliability, thus enabling the development of advanced Emergency Management Services based on Earth Observation technologies. Preliminary results concerning the use of S1 IW SAR data for geohazard monitoring and mapping are presented in this study. The first example concerns the analysis of the Mexico city test site, subject to strong subsidence (up to 2.5 cm/month) due to ground water extraction from the aquifer located beneath the metropolitan area, and where around 20 VV images have been acquired on ascending passes from October 2014 to date. Ground surface displacements have been measured through the SPINUA processing chain, an advanced Multi-Temporal SAR Interferometric algorithm that has been recently upgraded to support S1 data. A second example concerns the study of an intense flood event occurred on 17 April 17 2015 in Quelimane, as reported by the Namibia Flood Dashboard, by using multi-polarized S1 data acquired just few hours after the rainfall peak. Quelimane is a seaport in Mozambique, close to the river “Rio dos Bons Sinais” and located in a region extremely prone to floods during the rainy season. The mapping of the flooded area is done by comparing the signature of flood water in both VH and VV polarized radar data. The mean backscattering signature profiles of various water bodies is analyzed to discriminate flood water from other water bodies.
Study carried out in the framework of the Apulia Space project (PON&REC 2007-2013, Cod: PON03PE_00067_6).
[Nit.RECAS2015] D. O. Nitti, "Nuove tecnologie per l'analisi di immagini da satellite", Workshop: Il DataCenter ReCaS di Bari, 9 July 2015. URL: https://goo.gl/7Y0TIu
[Ref.JSTARS2014] A. Refice, D. Capolongo, G. Pasquariello, A. D'Addabbo, F. Bovenga, R. Nutricato, F.P. Lovergine, L. Pietranera, "SAR and InSAR for Flood Monitoring: Examples With COSMO-SkyMed Data". IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, Vol. 7, Issue 10, 2014. ISSN: 1939-1404. Scopus: 2-s2.0-84906948179. WOS:000341568700002. DOI: 10.1109/JSTARS.2014.2305165. IF: 3.97 (Year: 2014 - Source: https://goo.gl/NwmoU1)
We apply high-resolution, X-band, stripmap COSMO-SkyMed data to the monitoring of flood events in the Basilicata region (Southern Italy), where multitemporal datasets are available with short spatial and temporal baselines, allowing interferometric (InSAR) processing. We show how the use of the interferometric coherence information can help to detect more precisely the areas affected by the flood, reducing false alarms and missed identifications which affect algorithms based on SAR intensity alone. The effectiveness of using the additional InSAR information layer is illustrated by RGB composites of various combinations of intensity and coherence data. Analysis of multitemporal SAR intensity and coherence trends reveals complex behavior of various field types, which we interpret through a Bayesian inference approach, based on a manual identification of representative scattering and coherence signatures of selected homogeneous fields. The approach allows to integrate external, ancillary information to derive a posteriori probabilistic maps of flood inundation accounting for different scattering responses to the presence of water. First results of this semiautomated methodology, using simple assumptions for the SAR signatures and a priori information based on the distance from river courses, show encouraging results, and open a path to improvement through use of more complex hydrologic and topo-hydrographic information.
The authors thank the editors and two anonymous reviewers for their comments and suggestions. SAR data were courtesy of e-Geos S.p.A. InSAR processing was performed by Dr. D.O. Nitti of GAP s.r.l.
[Was.EngGeo2014] Wasowski J., Bovenga F. 2014. Investigating landslides and unstable slopes with satellite Multi Temporal Interferometry: Current issues and future perspectives. Engineering Geology 174: 103–138. DOI:10.1016/j.enggeo.2014.03.003. Scopus:2-s2.0-84898447338. WOS:000335630500009. ISSN:0013-7952. eISSN:1872-6917. IF(2018):3.909, IF(5years):4.42 (Source:WOS).
"Multi Temporal Interferometry (MTI) stands for advanced synthetic aperture radar differential interferometry (DInSAR) techniques, which include Permanent/Persistent Scatterers Interferometry - PSInSAR\u2122/PSI and similar methods, as well as Small Baseline Subset - SBAS and related/hybrid approaches. These techniques are capable to provide wide-area coverage (thousands of km2) and precise (mm-cm resolution), spatially dense information (from hundreds to thousands of measurement points/km2) on ground surface deformations. New MTI application opportunities are emerging thanks to i) greater data availability from radar satellites, and ii) improved capabilities of the new space radar sensors (X-band Cosmo-SkyMed, C-band RADARSAT-2, TerraSAR-X) in terms of resolution (from 3 to 1m) and revisit time (from 11 to 4days for X-band acquisitions). This implies greater quantity and quality information about ground surface displacements and hence improved landslide detection and monitoring capabilities. Even though the applicability of MTI to regional and local-scale investigations of slow landslides has already been demonstrated, the awareness of the MTI utility and its technical limitations among landslide scientists and practitioners is still rather low. By referring to recent works on radar remote sensing, many regional and local scale MTI application examples from the geoscience literature and our own studies, we present an up-to-date overview of current opportunities and challenges in this field. We discuss relevant technical constraints and data interpretation issues that hamper the use of MTI in landslide assessment. Then guidelines on how to mitigate MTI technical limitations and avoid erroneous interpretations of radar-derived slope surface deformations are presented for the benefit of users lacking advanced knowledge in SAR applications. Finally, in view of the upcoming radar satellite launches, future perspectives on MTI applications are outlined and recommendations for applied research priorities are suggested. We foresee that with regular globe-scale coverage, improved temporal resolution (weekly or better) and freely available imagery, new radar satellite background missions such as the European Space Agency's Sentinel-1 will guarantee ever increasing and more efficient use of MTI in landslide investigations. Furthermore, thanks to the improved temporal and spatial resolutions of the new generation radar sensors, significant breakthroughs are expected in detailed slope instability process modeling (e.g. kinematic and geotechnical models), as well as in the understanding of spatial and temporal patterns of landslide movement/activity and their relationships to causative or triggering factors (e.g. precipitation, seismic loading).
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The CSK imagery for the Zhouqu site, China was provided by the Italian Spatial Agency (ASI) within the COSMO-SkyMed AO Project ID 1820. ENVISAT and CSK data for St. Moritz (Switzerland), Madesimo, Bindo and Assisi (Italy) were provided respectively by the European Space Agency (ESA) and ASI in the framework of the MORFEO project funded by ASI (Contract no. I/045/07/0). CSK imagery for the test site in Calabria Region (Italy) provided by ASI (Agenzia Spaziale Italiana) in the framework of the project “Landslide Monitoring and Mapping System — CAR-SLIDE” (PON 01 00536). ENVISAT data for Volturino site provided by ESA under CAT-1 project ID 2653 in the framework of Puglia Region project “FRANE PUGLIA — Rilevamento di deformazioni al suolo con tecniche satellitari avanzate”. We thank Raffaele Nutricato and Davide Oscar Nitti of GAP srl for providing MTI processing through SPINUA algorithm. Comments by two anonymous reviewers and suggestions by the journal's EditorHsein Juang helped us improve thiswork.We also thank Qu Shannon (ELS-BEI) for soliciting this review article.
Book Chapters
[Was.WLF2014] J. Wasowski, F. Bovenga, T. Dijkstra, X. Meng, R. Nutricato, and M. T. Chiaradia, "Persistent Scatterers Interferometry provides insight on slope deformations and landslide activity in the mountains of Zhouqu, Gansu, China", World Landslide Forum 2014 (Bejing), in "Landslide Science for a Safer Geoenvironment", K. Sassa et al. (eds.), Vol. 2, pp 359-364. Springer International Publishing Switzerland 2014 ISBN: 978-3-319-05049-2 (Print) 978-3-319-05050-8 (Online). Scopus: 2-s2.0-84905398788. DOI 10.1007/978-3-319-05050-8_56. Proceedings of Third World Landslide Forum (WLF3), Beijing, China, 2–6 June 2014.
We present the results of Persistent Scatterers Interferometry (PSI) applied to investigate slope instabilities in a remote high mountain region of Southern Gansu, known to be prone to large magnitude (M7-8) earthquakes and catastrophic slope failures. The PSI processing of high resolution (~3 m) COSMO/SkyMed (CSK) satellite images produced spatially dense information (more than 1,000 PS/km2) on ground surface displacements in the area of Zhouqu, a town located in the Bailong River valley. A substantial portion of the radar targets showed significant displacements (from few to over 50 mm/year), denoting widespread occurrence of slope instabilities. In particular, the PSI results provided valuable information on the activity of some very large, apparently slow landslides that represent a persistent hazard to the local population and infrastructure. Monitoring movements of large long-lived landslides is important especially when, as in the case of the Bailong valley, they are known to undergo periods of increased activity resulting in river damming and disastrous flooding. Given the general lack of monitoring data on large landslides at Zhouqu and on other similar major failures that are common in Southern Gansu, the PSI derived displacements offer unique information, which, following expert judgment, can be used for preliminary wide-area assessments of hazards linked to landslide activity. Furthermore, this study shows that with the high resolution CSK data resulting in high radar target density, PSI can also assist in slope/landslide-specific assessments.
Work supported in part by the Italian Spatial Agency (ASI) - COSMO-SkyMed AO Project ID 1820. COSMO imagery provided by ASI. Special thanks to Dr Jie Gong and Lanzhou University students (Peng Guo, Guan Chen, Yajun Li, Runqiang Zeng, Liang Qiao, Wei Zhou, Haixiao Zhang, Xiaobin Yang) for valuable assistance with fieldwork.
[Was.Shroder2014] Wasowski J., Bovenga F. "Remote Sensing of Landslide Motion with Emphasis on Satellite Multitemporal Interferometry Applications: An Overview". Chapter 11 of Book: Landslide Hazards, Risks and Disasters, 2015, Pages 345-403. DOI:10.1016/B978-0-12-396452-6.00011-2. Scopus:2-s2.0-84942114404. ISBN:978-0-12-396452-6.
Landslide hazard reduction can benefit from increased exploitation of affordable remote sensing systems, with a focus on early detection of ground deformations, long-term monitoring, and possibly early warning of catastrophic failure. Among several innovative space-based remote-sensing techniques, synthetic aperture radar (SAR) and multitemporal interferometry (MTI) hold the most promise, because of its capacities and strengths: (1) wide-area coverage (tens of thousands of square kilometers) combined with a high spatial resolution (up to 1 m for the new generation of radar sensors) and hence the possibility of conducting multiscale investigations with the same data sets (from regional to slope-specific); (2) systematic, high-frequency (from a few days to weeks) measurements over long periods (years); (3) a high precision of surface displacement measurements (millimeters–centimeters) only marginally affected by poor weather conditions; (4) cost effectiveness, especially in the case of long-term, large-area investigations (catchment to regional scale); and (5) integration of landslide monitoring (based on new satellite imagery) with retrospective studies (archived imagery) to investigate slope failure history or landslide reactivation/acceleration processes. We illustrate the potential of MTI and explain how it can be used to detect and monitor landslide motion by considering applications in areas with a broad range of geomorphic, climatic, and vegetation conditions. The chosen examples of local-to-catchment-scale MTI case studies focus on unstable hill slopes and landslides in the Apennines (Italy), the European Alps, and on the island of Haiti. The potential of MTI is further assessed by also considering the strengths and limitations of other innovative applications of remote sensing in landslide monitoring, which rely on several recent or emerging techniques: Corner Reflector SAR interferometry, which exploits artificial targets installed on the ground and radar satellite imagery; ground-based InSAR; air- and ground-borne Light Detection And Ranging (LiDAR); and air/space-borne image matching. These applications, however, typically focus on single failed slopes and their use for regular, wide-area mapping of ground surface changes is at present economically prohibitive. We foresee that MTI will make landslide monitoring more effective and more affordable in more situations, and will become increasingly more important in cases where little or no conventional monitoring is feasible (e.g., remote locations and limited funds). We also expect that the role of prevention in slope hazard management can be enhanced by capitalizing more on the presently underexploited advantage of MTI, that is, its ability to regularly provide vast amounts of quantitative information on slope/ground stability conditions in large areas currently unaffected (or thought to be unaffected) by landslides, but where the terrain geomorphology and geology may indicate potential for future failures. Finally, we stress that high spatial and temporal resolution satellite remote sensing of ground deformations open new possibilities for landslide research and for more timely and detailed slope hazard assessment.
ENVISAT and CSK data for Garzeno, and Madesimo (Italy) were provided, respectively, by the European Space Agency (ESA) and by ASI in the framework of the MORFEO project funded by ASI (Contract n. I/045/07/0). ENVISAT data for Volturino site were provided by ESA under CAT-1 project ID 2653 in the framework of Puglia Region project "FRANE PUGLIA - Rilevamento di deformazioni al suolo con tecniche satellitari avanzate." We thank Raffaele Nutricato and Davide Oscar Nitti of GAP srl for providing MTI processing through SPINUA algorithm. We are grateful to Alessandro Ferretti and his colleagues at TRE srl (Milan, Italy) for sharing with us the results of SqueeSAR processing for the Madesimo study area. We also thank Giovanni Nico (CNR-IAC, Bari) and his colleagues at DIAN srl (Matera, Italy) for providing the example of GBInSAR application. Finally, we are indebted to this Volume Editor Tim Davies for his help and suggestions.
International Conference Proceedings
[Nit.EUSAR2014] D. O. Nitti, F. Bovenga, R. Nutricato, A. Refice, M. F. Bruno, A. F. Petrillo, M. T. Chiaradia, "On the use of Numerical Weather Models for improving SAR geolocation accuracy". Proceedings of EuSAR 2014 - 10th European Conference on Synthetic Aperture Radar, Berlin, Germany, 03-05 June 2014, VDE edt., ISBN: 978-3-8007-3607-2. ISSN: 2197-4403. Scopus: 2-s2.0-84994571247. URL: https://www.vde-verlag.de/proceedings-en/453607109.html
In order to ensure sub-pixel accuracy of geocoded SAR products, accurate estimation and correction of the Atmospheric Path Delay (APD) is needed, in particular for the new generation of high resolution satellite SAR sensors (TerraSAR-X, COSMO/SkyMED). The present work aims at assessing the performances of operational Numerical Weather Models (NWM) as tools for estimating the APD along the SAR signal acquisition geometry. The Regional Atmospheric Modeling System (RAMS) has been selected for this purpose. In order to guarantee an accurate knowledge of both the satellite orbit and target position, TerraSAR-X data and corner reflectors have been used for the experiment.
TSX data are provided by DLR (TSX General AO Project MTH0432). CSK data provided by ASI (AO-COSMO Project ID-1462). This work has been partially funded by MIUR (CARSLIDE project, PON01_00536).
[Dad.IGARSS2014] A. D’addabbo, A. Refice, G. Pasquariello, F. Bovenga, M. T. Chiaradia, D.O. Nitti, "A Bayesian Network for Flood Detection". Proceedings of 2014 IGARSS - International Geoscience and Remote Sensing Symposium, Québec, Canada, 13-18 July 2014 . ISSN: 2153-6996. eISSN: 2153-7003 . Scopus: 2-s2.0-84911416044. WOS:000349688105041. DOI: 10.1109/IGARSS.2014.6947260
We apply a Bayesian Network (BN) paradigm to the problem of monitoring flood events through synthetic aperture radar (SAR) and interferometric SAR (InSAR) data. BNs are well-founded statistical tools which help formalizing the information coming from heterogeneous sources, such as remotely sensed images, LiDAR data, and topography. The approach is tested on the fluvial floodplains of the Basilicata region (southern Italy), which have been subject to recurrent flooding events in the last years. Results show maps efficiently representing the different scattering/coherence classes with high accuracy, and also allowing separating the multitemporal dimension of the data, where available. The BN approach proves thus helpful to gain insight into the complex phenomena related to floods, possibly also with respect to comparisons with modeling data.
[Bov.SPIE2014] F. Bovenga, A. Refice, G. Pasquariello, D. O. Nitti, R. Nutricato, "Corner reflectors and multi-temporal SAR inteferometry for landslide monitoring". Proc. SPIE 9243, SAR Image Analysis, Modeling, and Techniques XIV, 92430I (October 21, 2014). Scopus: 2-s2.0-84922682392. WOS:000349373200015. DOI: 10.1117/12.2066833. ISSN 0277-786X.
The application of Persistent Scatterer Interferometry (PSI) to slope instability monitoring poses challenges related to the complex kinematics of the phenomenon, as well as to the unfavourable settings of the area affected by landslides, often occurring on sites of limited extension, characterized by steep topography and variable vegetation cover. New-generation SAR sensors, such as TerraSAR-X (TSX) thanks to their higher spatial resolution, make PSI applications very promising for monitoring areas with low density man-made. Nevertheless, the application of techniques still remains problematic or impossible in rural and mountainous areas. This is the case, for instance, for the Municipality of Carlantino, in Southern Italy. Both medium resolution SAR data from ESA satellites, and X-band high resolution SAR data from the TSX satellite, were processed through the PSI algorithm SPINUA. Despite the higher spatial density of PS from TSX, the landslide body is lacking coherent targets, due to vegetation and variable land cover. To allow stability monitoring, a network of six CRs was designed and deployed over the landslide test site. Twenty-six TSX stripmap images were processed by using both PSI and an ad hoc procedure based on double-difference analysis of DInSAR phase values on the CR pixels, constrained by the accurate CR height measurements provided by DGPS. Despite the residual noise due to the sub-optimal CR network and the strong atmospheric signal, displacement estimation on the CRs allows to propagate the PSI results downslope, proving the stability of the landslide area subjected to consolidation works.
Work supported by the Italian Ministry of Research in the framework of PRIN 2008 research grant "Advanced technologies in the assessment and mitigation of the landslide risk: precursors detection, previsional models and thematic mapping". TerraSAR-X data are provided by DLR under TerraSAR-X General AO Project ID MTH0432. PS map on Carlantino from TSX data was obtained by GAP srl in the framework of the Puglia Region project "FRANE PUGLIA - Rilevamento di deformazioni al suolo con tecniche satellitari avanzate". Authors thanks Ing. Pino d’Amelio for supporting the deployment activity.
[Con.SPIE2014] D. Conte, F. Bovenga, A. Refice, D. O. Nitti, R. Nutricato, M. T. Chiaradia, "Suitability of COSMO-SkyMed constellation for radargrammetric DEM generation". Proc. SPIE 9243, SAR Image Analysis, Modeling, and Techniques XIV, 924302 (October 21, 2014). DOI: 10.1117/12.2066846. Scopus: 2-s2.0-84922623255. WOS:000349373200001. ISSN 0277-786X.
The COSMO-SkyMed (CSK) constellation acquires data from its four SAR X-band satellites in several imaging modes, providing in particular different view angles. The present work investigates the potential of CSK constellation for ground elevation measurement through SAR radargrammetry. We selected an area around Parkfield (California), where several CSK acquisitions are available. We used for radargrammetric processing 2 CSK spotlight image pairs acquired at 1 day of separation, in Same Side Viewing configuration, with baselines of 350 km. Furthermore, a dataset of 33 spotlight images were selected to derive height measurements through both persistent scatterers interferometry(PSI) and interferometric processing of 5 1-day separated pairs included in the dataset. We first predict how the errors in the geometrical parameters and the correlation level between the images impact on the height accuracy. Then, two DEMs were derived by processing the radargrammetric CSK pairs. According to the outcomes of the feasibility analysis, processing parameters were chosen in order to guarantee nominal values of height accuracy within the HRTI Level 3 specifications. The products have a final resolution of 3 m. In order to assess the accuracy of these radargrammetric DEMs, we used the height values provided by the PSI, and an interferometric DEM derived from the CSK tandem-like pairs.
COSMO/SkyMed data used for SAR interferometry are provided by the Italian Space Agency (ASI) in the framework of the AO-COSMO Project ID-1462 "Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation" - ASI Contract I/063/09/0. COSMO/SkyMed data used for radargrammetry are provided by ASI in the framework of D. Conte's PhD research project “Caratterizzazione di bersagli non cooperanti e misure di quota di precisione mediante tecniche interferometriche e radargrammetriche multitemporali con immagini satellitari acquisite dalla costellazione COSMO/SkyMed”. Authors thank Dr. Francesco Nirchio from ASI for his support.
[Nut.SPIE2014] R. Nutricato, D. O. Nitti, F. Bovenga, A. Refice, M. T. Chiaradia, "Exploitation of a large COSMO-SkyMed interferometric dataset". Proc. SPIE 9243, SAR Image Analysis, Modeling, and Techniques XIV, 92430C (October 21, 2014). DOI: 10.1117/12.2067156. Scopus: 2-s2.0-84922671767. WOS:000349373200010. ISSN 0277-786X.
In this work we explored a dataset made by more than 100 images acquired by COSMO-SkyMed (CSK) constellation over the Port-au-Prince (Haiti) metropolitan and surrounding areas that were severely hit by the January 12th, 2010 earthquake. The images were acquired along ascending pass by all the four sensors of the constellation with a mean rate of 1 acquisition/week. This consistent CSK dataset was fully exploited by using the Persistent Scatterer Interferometry algorithm SPINUA with the aim of: i) providing a displacement map of the area; ii) assessing the use of CSK and PSI for ground elevation measurements; iii) exploring the CSK satellite orbital tube in terms of both precision and size. In particular, significant subsidence phenomena were detected affecting river deltas and coastal areas of the Port-au-Prince and Carrefour region, as well as very slow slope movements and local ground instabilities. Ground elevation was also measured on PS targets with resolution of 3m. The density of these measurable targets depends on the ground coverage, and reaches values higher than 4000 PS/km2 over urban areas, while it drops over vegetated areas or along slopes affected by layover and shadow. Heights values were compared with LIDAR data at 1m of resolution collected soon after the 2010 earthquake. Furthermore, by using geocoding procedures and the precise LIDAR data as reference, the orbital errors affecting CSK records were investigated. The results are in line with other recent studies.
COSMO/SkyMed data provided by the Italian Space Agency (ASI) in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS) of Haiti and the Department of Physics (DIF) of the University of Bari, Italy. LIDAR data were acquired by Rochester Institute of Technology and Kucera International, under sub-contract to ImageCat Inc. and funded by the Global Facility for Disaster Reduction and Recovery (GFDRR) hosted at The World Bank (DOI:10.5069/G96Q1V50). This study was partly funded by the HALL project (“Plasma propulsion system for the growth of Apulian Aerospace Industry”), in the framework of the PO FESR Apulia 2007/2013, Line 1.2, Action 1.2.4.
National Conference Proceedings
[Chi.SCORE2014] M. T. Chiaradia, R. Nutricato, D. O. Nitti, K. Tijani, L. Guerriero, F. Ciola, F. Intini, F. Bovenga, A. Refice, G. Pasquariello, J. Wasowski, G. Milillo, "CAR-SLIDE project: integration of EO technologies and diagnostic systems for advanced transport infrastructure monitoring". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2964-6.
CAR-SLIDE is a MIUR project (PON RandC 2007-2013) aimed to implement an advanced diagnostic system capable to monitor landslide and flood events along the national rail networks, by integrating in situ data detected from on board sophisticated innovative measuring systems, with Earth Observation techniques (based on weather forecast, SAR and optical data). In order to highlight the potential of COSMO/SkyMed satellite data for geohazard detection and mapping, two test cases are presented in this work. The first one consists in the application of multitemporal SAR/InSAR techniques for monitoring recent flood events in the Basilicata region, causing rail service interruptions. The second example consists in a retrospective analysis on the detection of precursory signals related to the landslide which occurred on January 2014 close to the town of Marina di Andora. The landslide caused the derailment of a train and the interruption of the railway line connecting north-western Italy to France.
Work funded by MIUR (CARSLIDE project, PON01_00536)
[Chi.SCORE2014b] M. T. Chiaradia, A. Morea, D. Conte, K. Tijani, G. Preziosa, L. Guerriero, R. Nutricato, D. O. Nitti, F. Ciola, F. Intini, F. Bovenga, A. Refice, G. Pasquariello, J. Wasowski, "Outline of Ongoing Research Activities of the Remote Sensing Group at the Physics Department of Bari". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2965-3.
The paper outlines the ongoing research activities of the Remote Sensing Group at the Physics Department of Bari in the field of image processing and Earth Observation, and related SW/HW technologies. In the framework of projects founded by national and international space agencies (ASI, ESA, NASA) and the European Community, the group is working in close collaboration with the ISSIA and IRPI institutes of the National Council of Research, in Bari, and Geophysical Applications Processing srl, a POLIBA spinoff company founded in 2006 that represents a valuable example of knowledge transfer from research institutions to industries. Research themes include: (1)development of advanced Multi-Temporal InSAR algorithms for geohazard detection and infrastructure stability analysis; (2)VIS/NIR remote sensing for the health monitoring of marine ecosystems or the detection of fish catch lines; (3)high resolution forecast services using non-hydrostatic NWP models for environmental risk prevention.
[Bru.SCORE2014] M. F. Bruno, B. Nobile, R. Francioso, R. Nutricato, D. O. Nitti, "Effective Coastal Areas Monitoring through COSMO-SkyMed high-resolution radar acquisitions". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2966-0.
Growing urbanization, human activities and climate changes are worsening shoreline erosion phenomena all around the Italian coasts. This requires a continuous monitoring activity, that is impractical in terms of costs and logistics through traditional in situ investigations over wide scale. Thanks to the all-weather day/night radar imaging capability and to the nationwide acquisition plan named MapItaly, devised by the Italian Space Agency and active since 2010, COSMO-SkyMed constellation is able to provide X-band images covering the Italian territory with a best effort revisit time of 16 days, thus enhancing Integrated Coastal Zone Management through Earth Observation (EO) techniques. The study is focused on the advanced EO system, named COSMO-Beach, designed for semi-automatic shoreline and coastal morphology identification. System features and performances are presented, together with its application on the coastal stretch between towns of Torre Canne and Savelletri (Apulia Region).
[Gue.SCORE2014] A. Guerriero, V. W. Anelli, A. Pagliara, R. Nutricato, D. O. Nitti, "High performance GPU implementation of InSAR time-consuming algorithm kernels". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2967-7.
Satellite remote sensing radar technologies provide powerful tools for geohazard monitoring and risk management at synoptic scale. In particular, advanced Multi-Temporal Interferometric processing algorithms are capable to detect ground deformations and structural instabilities with millimetric precision, but impose strong requirements in terms of hardware resources. Recent advances in GPU computing and programming hold promise for time efficient implementation of imaging algorithms, thus enhancing the development of advanced Emergency Management Services based on Earth Observation technologies. In this study, a preliminary assessment of the potentials of GPU processing is carried out, by comparing CPU (single- and multi-thread) and GPU implementations of InSAR time-consuming algorithm kernels. In particular, it is focused on the fine coregistration of SAR interferometric pairs, a crucial step in the interferogram generation process. Experimental results are presented and discussed.
The ENVISAT satellite images were made freely available by ESA (dataset SAR Italy earthquake April 2009).
[Chi.SCORE2014t] M. T. Chiaradia, D. Conte, F. Bovenga, A. Refice, L. Guerriero, F. Nirchio, "COSMO-SkyMed constellation capabilities for DEM generation". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2965-3.
The COSMO/SkyMed (CSK) constellation acquires data from its four SAR X-band satellites in several imaging modes and different view angles. The paper investigates its capabilities for ground elevation measurement through both radargrammetric and interferometric techniques, and evaluates the impact of the improved spatial resolution with respect to the previous SAR sensors. Parkfield (California, USA) has been selected as test site thanks to the availability of consistent dataset of CSK images acquired in both stripmap and spotlight modes. The interferometric analysis shows that, under proper conditions, tandem-like pairs with normal baselines higher than 300 m allow to derive interferometric DEMs fulfilling the HRTI Level 3 standard. SAR radargrammetry is less accurate but more robust than interferometric methods, which can be strongly affected by coherence losses, atmospheric artifacts and phase unwrapping errors. Persistent Scatterers are used as GCPs for the performance assessment.
This work has been partly funded by the Italian Space Agency in the context of the CRESP project (Cosmo Radar Expert System of Processing), in the framework of the second thematic announcement on "Earth Observation" reserved to SME.
[Chi.SCORE2014q] M. T. Chiaradia, L. Guerriero, K. Tijani, A. Morea, F. Ciola, G.Pasquariello, "Fishing Grounds Detection by Satellite Remote Sensing Techniques". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2967-7.
Quick detection of fishing grounds using satellite based remote sensing techniques can significantly reduce the searching time, the usage of fuel and the human effort and increase the CPUE (Catch per unit effort). Multi-temporal and multi-sensor data fusion techniques have been applied to MODIS-AQUA, MODIS-TERRA and VIIRS multi-spectral data to detect chlorophyll and temperature fronts in the low Adriatic and in the Ionian seas. These fronts are generated by the upwelling of cold waters rich of phytoplankton nutrients where an high concentration of pelagic fish is expected. CPUE data have been provided by the FEDERPESCA fleet relative to the 2013 and 2014 fishing campaigns conducted in the areas of interest. An automatic procedure has been developed to calibrate and validate the production in near-real time of daily maps of expected good fishing grounds to be provided to the FEDERPESCA fleet. The same procedure could be optimized also for other seas.
Work funded by Apulia Region, in the framework of the project "Sustainable Fishery" (FEP 2007-2013 – Measure 3.1)
[Mol.SCORE2014] M. G. Molfetta, A. Morea, G. Preziosa, "A new approach for measuring short water waves through stereo image sequences and artificial markers". First WORKSHOP on the State of the art and Challenges Of Research Efforts @POLIBA (SCORE@POLIBA), December 3-5, 2014, Politecnico di Bari, Italy. ISBN: 978-88-492-2966-0.
We present an innovative approach to obtain, with a single instrument, measurements of several wave motion parameters of interest in physical models of marine hydraulics. The system, realized and tested in a laboratory environment, is based on stereo computer-vision techniques. A number of colored floating markers with low inertia are evenly distributed in the field of view of two synchronized movie-cameras, whose frame cover large portions of the hydraulic model. Specific computer-vision procedures are implemented to analyze acquired data. The system captures wave data simultaneously in a high number of points of the wave field and overcomes some limitations of the commonly used probes, limited in numbers, more intrusive and in need of frequent calibration. The system achieved good measurement’s accuracy within 5% in terms of significant wave height and 1% in terms of frequency spectrum, in comparison to the traditional calibration probes.
[Was.IGU2014] J. Wasowski, F. Bovenga, R. Nutricato, D.O. Nitti, M.T. Chiaradia, "Satellite multi-temporal interferometry for local and regional scale slope instability and subsidence hazard assessment". 2014 International Geographical Union Regional Conference, Kraków, Poland, 18-22 August 2014. Abstracts IGU2014–0964. http://www.igu2014.org/programme_detailed/pdf/12_gh1/Wasowski_Satellite.pdf
Satellite multi-temporal interferometry (MTI) is appealing to scientists and end users concerned with ground instability hazards because it can provide very precise information on slow ground surface displacements over vast areas with limited vegetation cover. The outstanding capacities and advantages of MTI applications include: (1) Wide-area coverage (tens of thousands of km2) combined with high spatial resolution (up to 1 m for the new generation radar sensors) and hence the possibility of conducting multi-scale investigations with the same datasets (from regional to site-specific); (2) Systematic, high frequency (from few days to weeks) measurements over long periods (years); (3) High precision of surface displacement measurements (mm-cm resolution) only marginally affected by bad weather conditions; (4) Cost-effective, especially in case of long-term, large area investigations (catchment to regional scale); (5) Integration of monitoring based on new satellite imagery with retrospective studies (using archived imagery) to investigate ground failure history and long-term instability processes (e.g. post-mining subsidence, landslide reactivation); (6) Regional scale, regular update on the persistence (or not) of ground stability conditions in inhabited areas or those to be urbanized (prevention and land use planning). Considering the advantages listed above, we foresee a possibility of future massive exploitation of MTI technology in ground instability hazard assessment. It is also expected that MTI applications could become increasingly more important in cases where little or no conventional monitoring is feasible (e.g. remote locations and limited funds). The main purpose of this work is to illustrate the potential of MTI and explain what kind of information this remote sensing technique can deliver. This is done by presenting case study examples of local to catchment scale MTI applications regarding slope instability and subsidence hazards in areas characterized by a wide range of geomorphic, climatic and vegetation conditions (China, Haiti, Italy and Poland).
The work has been in part supported by the MORFEO project funded by the Italian Spatial Agency(ASI) (Contract n. I/045/07/0). ASI also provided COSMO-SkyMed imagery of China under AO Project ID 1820, as well as imagery of Haiti in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS), Haiti and the Department of Physics (DIF) of the University of Bari, Italy. ENVISAT and TerraSAR-X data were provided, respectively, by the European Space Agency (ESA) under project ID 2653 and by the German Space Agency (DLR) under TerraSAR General AO Project ID MTH0432.
[Was.AGU2014] J. Wasowski, M. T. Chiaradia, F. Bovenga, R. Nutricato, D. O. Nitti, G. Milillo, "Exploiting COSMO-Skymed Data and Multi-Temporal Interferometry for Early Detection of Landslide Hazard: A Case of Slope Failure and Train Derailment Near Marina Di Andora, Italy". AGU Fall Meeting 2014, Abstract ID:6747, Poster Presentation NH11B-3703, San Francisco, California, USA, 15-19 December 2014.
The improving temporal and spatial resolutions of new generation space-borne X-Band SAR sensors such as COSMO-SkyMed (CSK) constellation, and therefore their better monitoring capabilities, will guarantee increasing and more efficient use of multi-temporal interferometry (MTI) in landslide investigations. Thanks to their finer spatial resolution with respect to data, X-band InSAR applications are very promising also for monitoring smaller landslides and single engineering structures sited on potentially unstable slopes. This work is focused on the detection of precursory signals of an impending slope failure from MTI time series of ground deformations obtained by exploiting 3 m resolution CSK data. We show the case of retrospectively captured pre-failure strains related to the landslide which occurred on January 2014 close to the town of Marina di Andora. The landslide caused the derailment of a train and the interruption of the railway line connecting north-western Italy to France. A dataset of 56 images acquired in STRIPMAP HIMAGE mode by CSK constellation from October 2008 to May 2014 was processed through SPINUA algorithm to derive the ground surface deformation map and the time series of displacement rates for each coherent radar target. We show that a cluster of moving targets coincides with the structures (buildings and terraces) affected by the 2014 landslide. The analysis of the MTI time series further shows that the targets had been moving since 2009, and thus could have provided a forewarning signal about ongoing slope or engineering structure instability. Although temporal landslide prediction remains difficult even via in situ monitoring, the presented case study indicates that MTI relying on high resolution radars such as CSK can provide very useful information for slope hazard mapping and possibly for early warning. Acknowledgments: DIF provided contribution to data analysis within the framework of CAR-SLIDE project funded by MIUR (PON01_00536).
DIF provided contribution to data analysis within the framework of CAR-SLIDE project funded by MIUR (PON01_00536).
[Was.AGU2014b] J. Wasowski, F. Bovenga, D. O. Nitti, R. Nutricato, M. T. Chiaradia, "High resolution satellite multi-temporal interferometry for landslide and subsidence hazard assessment: An overview". AGU Fall Meeting 2014, Abstract ID:3759, Oral Presentation NH14A-02 (Invited), San Francisco, California, USA, 15-19 December 2014.
The new and planned satellite missions can not only provide global capacity for research-oriented and practical applications such as mapping, characterizing and monitoring of areas affected by slope and subsidence hazards, but also offer a possibility to push the research frontier and prompt innovative detailed-scale studies on ground movement dynamics and processes. Among a number of emerging space-based remote sensing techniques, synthetic aperture radar (SAR), multi-temporal interferometry (MTI) seems the most promising for important innovation in landslide and subsidence hazards assessment and monitoring. MTI is appealing to those concerned with terrain instability hazards because it can provide very precise information on slow displacements of the ground surface over vast areas with limited vegetation cover. Although MTI techniques are considered to have already reached the operational level, it is apparent that in both research and practice we are at present only beginning to benefit from the high-resolution imagery that is currently acquired by the new generation radar satellites (e.g. COSMO-SkyMed, TerraSAR-X). In this overview we illustrate the great potential of high resolution MTI and explain what this technique can deliver in terms of detection and monitoring of slope and subsidence hazards. This is done by considering different areas characterized by a wide range of geomorphic, climatic and vegetation conditions, and presenting selected case study examples of local to regional scale MTI applications from Europe, China and Haiti. We envision that the current approach to assessment of hazard can be transformed by capitalizing more on the presently underexploited advantage of the MTI technique, i.e. the capability to provide regularly spatially-dense quantitative information for large areas currently unaffected by instabilities, but where the terrain geomorphology and geology may indicate potential for future ground failures.
[Chi.AGU2014] M.T. Chiaradia, K. Tijani, A. Morea, R. Nutricato, L. Guerriero, L. Giannini, L. Nannucci, "Multi-platform Chlorophyll and Sea Surface Temperature data fusion for Potential Fishing Zone detection using MODIS/VIIRS and ancillary data". AGU Fall Meeting 2014, Abstract ID:16210, Poster Presentation OS34B-08, San Francisco, California, USA, 15-19 December 2014.
Satellite remote sensing data are being successfully used in several countries to localize potential fishing zones (PFZ). Oceanographic conditions related to water temperature and nutrient distribution strongly influence natural concentration of fish stocks and can be identified as oceanic upwelling fronts using information about Sea Surface Temperature (SST) and Chlorophyll Concentration (CHL) obtained from satellite data. In this context, the present work illustrates a satellite-based near-real time fishery forecasting system tuned for the Adriatic Sea in order to help fishermen in saving fuel and ship time. More specifically, we developed an innovative multi-mission, multi-sensor and multi-temporal data fusion technique for the automatic identification of the upwelling fronts from the geometry of the distribution of the SST and CHL and of their gradients, using observations from the ocean color MODIS sensors of Terra and Aqua NASA satellites in conjunction with appropriate data from the VIIRS sensor on the Suomi/NPP satellite. To this aim, precision geo-referencing and masking procedures were used to allow automatic selection of good quality pixels. A time stack of the final maps has been obtained as three-day running average with one-day step, taking into account the average local duration of the upwelling fronts. Finally, a gradient-based edge detection algorithm using the Canny filter has been applied to each of the three-day composite maps, based on the distribution of the SST and CHL and of their gradients, for the determination of the fronts as potential fishing zones. The procedure is being validated using the geographic information of categorized fish Catch Per Unit Effort (CPUE) of the 2013 fishing campaigns of the FEDERPESCA fleet, as part of the project "Sustainable Fishery", funded by Apulia Region, in Southern Italy (FEP 2007-2013 – Measure 3.1 ), for the development of a satellite-based near-real time fishery forecasting system to be used in the Adriatic Sea. The results of this study will be presented and commented. Moreover, our results show that data fusion applied to information obtained from different platforms and instruments, although with not overlapping wavebands and different spectral sensitivity, can give important contribution.
Work funded by Apulia Region, in the framework of the project "Sustainable Fishery" (FEP 2007-2013 – Measure 3.1)
[Tij.EGU2014] K. Tijani, A. Morea, M.T. Chiaradia, L. Guerriero, G. Pasquariello, R. Nutricato, "The retrieval of the Potential Fishing Zone (PFZ) information using satellite based chlorophyll and sea surface temperature along the north of Adriatic sea". Abstracts proceedings EGU 2014, Vienna, Austria, 27 April - 02 May 2014. Abstract ID-No: EGU2014-13684. Vol. 16 eISSN: 1607-7962.
Relevant oceanographic conditions, such as sea surface temperature (SST), chlorophyll concentration (CHL) and oceanic fronts, which strongly influence natural fluctuations of fish stocks, can be observed and measured by remote sensors on satellites and aircraft. The high spatiotemporal frequency of MODIS data (twice per day, 500m resolution) are provided in near-real time to help fishermen save fuel and ship time during their search for fish located along the Adriatic Sea. The purpose of this work is the integration of CHL and SST to generate potential fishing zones (PFZs) using an gradient-based edge detection algorithm [1]. The position of the fronts is detected by a Canny filter [2] were applied to gradient of CHL and SST images; the potential edges were subsequently validated statistically [3] and then were compared in terms of categorized fish catch per unit effort (CPUE, total catch divided by actual fishing hours). The results of this study will be presented and commented.
Work funded by Apulia Region, in the framework of the project "Sustainable Fishery" (FEP 2007-2013 – Measure 3.1)
[Was.EGU2014] J. Wasowski, F. Bovenga, T. Dijkstra, X. Meng, R. Nutricato, and M. T. Chiaradia, " Towards widespread exploitation of high resolution multi-temporal interferometry for monitoring landslide activity: a case-study of Southern Gansu, China". Abstracts proceedings EGU 2014, Vienna, Austria, 27 April - 02 May 2014. Abstract ID-No: EGU2014-14995. Vol. 16 eISSN: 1607-7962.
Although Multi-Temporal Interferometry (MTI) techniques are considered to have already reached the operational level, it is apparent that, in both research and practice, we are only just beginning to benefit from the high resolution imagery that is currently acquired by the new generation of radar satellites. MTI techniques are not applicable in any environment, but, nonetheless, we foresee a strong possibility that in the future these techniques will see widespread exploitation in support of slope hazard assessments. MTI applications will become increasingly important in cases where little or no conventional monitoring is feasible (e.g. remote locations and limited funds). The tremendous potential of MTI is illustrated using selected examples of applications ranging from local to catchment scales. A particular focus is on the use of MTI for the investigation of slope instability in the remote high mountain region of Zhouqu, Southern Gansu, known to be affected by large magnitude (M7-8) earthquakes and catastrophic mass movements. The MTI processing of high resolution (3 m) COSMO/SkyMed (CSK) satellite images produced spatially dense information (more than 1000 radar targets/km2) on ground surface displacements. A substantial portion of the radar targets showed significant displacements (from few to over 100 mm/yr), denoting widespread slope instability. In particular, the MTI results provided valuable information on the activity of some very large, apparently slow moving landslides that represent a persistent hazard to the local population and infrastructure, particularly as these landslides are known to undergo periods of increased activity resulting in river damming and disastrous flooding. Given the general lack of field monitoring data on slope instability in Southern Gansu, the MTI-derived displacements offer a unique form of remote displacement monitoring that provides valuable information to experts tasked with formulating strategies for hazard management in these difficult terrains. Furthermore, this study shows that high resolution CSK imagery results in high radar target density, so that MTI can also assist with site specific scale assessments of slope deformation hazards.
[Nit.NEREUS2014] D. O. Nitti, "Monitoring of Transport Infrastructures by Using Synthetic Aperture Radar Satellites". NEREUS International Conference "Space4You - Space, a driver for Competitiveness and Growth", Bari,27-28 February 2014. http://www.nereus-regions.eu/sites/all/events/BARI/PPT/NEREUS_Space4You_Nitti_27Feb2014.v3.pdf
[Bov.IJRS2013] F. Bovenga, D. O. Nitti, G. Fornaro, F. Radicioni, A. Stoppini, R. Brigante, "Using C/X-band SAR interferometry and GNSS measurements for the Assisi landslide analysis". International Journal of Remote Sensing, vol. 34(11), pp. 4083-4104, 2013. DOI:10.1080/01431161.2013.772310. ISSN 0143-1161 (Print), 1366-5901 (Online). Scopus: 2-s2.0-84874595989. IF: 1.14 (Year: 2012 - Source: ResearchGate - http://is.gd/ZyQELr)
This work presents an analysis of the applicability of synthetic aperture radar (SAR) interferometry to landslide monitoring. This analysis was carried out by using differ- ent interferometric approaches, different spaceborne SAR data (both in the and in the X-band), and in situ global navigation satellite system (GNSS) measurements. In particular, we investigated both the reliability of displacement monitoring and the issues of the cross-comparison and validation of the interferometric synthetic aperture radar (InSAR) results. The work was focused on the slow-moving landslide that affects a relevant part of the urban area of the historical town of Assisi (Italy). A ENVISAT advanced synthetic aperture radar (ENVISAT ASAR) dataset acquired between 2003 and 2010 was processed by using two different interferometric techniques, to allow cross-comparison of the obtained displacement maps. Good corre- spondence between the results was found, and a deeper analysis of the movement field was possible. Results were further compared to a set of GNSS measurements with a 7 year overlap with SAR data. A comparison was made for each GNSS marker with the surrounding SAR scatterers, trying to take into account local topological effects, when possible. Further, the high-resolution X-band acquired on both ascending and descending tracks by the COSMO-SkyMed (CSK) constellation was processed. The resultant dis- placement fields show good agreement with and GNSS measurements and sensible increase in the density of measurements.
ENVISAT and COSMO-SkyMed data were provided, respectively, by ESA and ASI in the framework of the MORFEO project (ASI contract no. I/045/07/0). We thank the Provveditorato alle Opere Pubbliche per la Toscana e l’Umbria for funding the GNSS monitoring activity on the Assisi landslide.
[Nit.EUJRS2013] D. O. Nitti, F. Bovenga, R. Nutricato, F. Intini, M. T. Chiaradia, “On the use of COSMO/SkyMed data and Weather Models for interferometric DEM generation”. European Journal of Remote Sensing, vol. 46, pp.250-271, 2013. DOI: 10.5721/EuJRS20134614. ISSN: 2279-7254. WOS:000318651700014. Scopus: 2-s2.0-84875201169. IF: 0.33 (Year: 2012 - Source: ResearchGate - http://is.gd/a1YHlW)
This work experiments the potentialities of COSMO/SkyMed (CSK) data in providing interferometric Digital Elevation Model (DEM). We processed a stack of CSK data for measuring with meter accuracy the ground elevation on the available coherent targets, and used these values to check the accuracy of DEMs derived from 5 tandem-like CSK pairs. In order to suppress the atmospheric signal we experimented a classical spatial filtering of the differential phase as well as the use of numerical weather prediction (NWP) model RAMS. Tandem-like pairs with normal baselines higher than 300 m allows to derive DEMs fulfilling the HRTI Level 3 specifications on the relative vertical accuracy, while the use of NWP models still seems unfeasible especially for X-band.
Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the project “AO-COSMO Project ID-1462 - Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation - ASI Contract I/063/09/0”.
[Ref.EUJRS2013] A. Refice, A. Belmonte, F. Bovenga, G. Pasquariello, R. Nutricato, “On the interpolation of sparse-grid InSAR data without need of phase unwrapping". European Journal of Remote Sensing, vol. 46, pp.807-821, 2013. DOI: 10.5721/EuJRS20134648. Scopus: 2-s2.0-84890397441. WOS:000328277100010. Online ISSN: 2279-7254. IF: 1.31 (Year: 2013 - Source: https://goo.gl/x5icVo)
Sparse phase measurements often need to be interpolated on regular grids, to extend the information to unsampled locations. Typical cases involve the removal of atmospheric phase screen information from Interferometric Synthetic Aperture Radar (InSAR) stacks, or the retrieval of displacement information over extended areas in Persistent Scatterers Interferometry (PSI) applications, when sufficient point densities are available. This operation is usually done after a phase unwrapping (PU) of the sparse measurements to remove the sharp phase discontinuities due to the wrap operation. PU is a difficult and error-prone operation, especially for sparse data. In this work, we investigate from the empirical point of view an alternative procedure, which involves an interpolation of the complex field derived from the sparse phase measurements. Unlike traditional approaches, our method allows to bypass the PU step and obtain a regular-grid complex field from which a wrapped phase field can be extracted. Under general conditions, this can be shown to be a good approximation of the original phase without noise. Moreover, the interpolated, wrapped phase field can be fed to state-of-the-art, regular-grid PU algorithms, to obtain an improved absolute phase field, compared to the canonical method consisting of first unwrapping the sparse-grid data. We evaluate the performance of the method in simulation, comparing it to the classical methodology described above, as well as to an alternative procedure, recently proposed, to reduce a sparse PU problem to a regular-grid one, through a nearest-neighbor interpolation step. Results confirm the increased robustness of the proposed method with respect to the effects of noise and undersampling.
[Nut.WLF2book2013] R. Nutricato, J. Wasowski, F. Bovenga, A. Refice, G. Pasquariello, D. O. Nitti, M. T. Chiaradia, "C/X-band SAR interferometry used to monitor slope instability in Daunia, Italy". Proceeding of the the Second World Landslide Forum, published in Volume 2 "Early warning, instrumentation and monitoring" of the Springer Book Series for WLF2 "Landslide science and practice", pp. 423-430, Springer-Verlag Berlin Heidelberg 2013. ISBN 978-3-642-31444-5. DOI: 10.1007/978-3-642-31445-2_55. Scopus: 2-s2.0-84898064174.
We apply multi-temporal Persistent Scatterer Interferometry (PSI) analysis to investigate slope instability in the Daunia region in the Southern Apennine Mountains. Daunia includes many small hill-top towns affected by landslides and is of particular interest for the Civil Protection – Regione Puglia Authority, one of the end users of the PSI deformation maps. The SPINUA algorithm is used to perform interferometric analysis and detect, with mm precision, the presence of ground surface movements. Consistent results on very slow displacements are obtained using the radar imagery acquired between 2002 and 2010 by the ENVISAT ESA satellite (, medium spatial resolution sensor) and the images acquired between 2010-2011 by the X-band high resolution sensor onboard the TerraSAR-X satellite. Thanks to the finer spatial resolution the X-band PSI applications are very promising for monitoring single man-made structures and slope/ground instability in areas where PS density is low.
Work supported by Puglia Region in the framework of the project “FRANE PUGLIA - Rilevamento di deformazioni al suolo con tecniche satellitari avanzate”. ENVISAT data are provided by ESA under CAT-1 project ID 2653. TerraSAR-X data are provided by DLR under TerraSAR-X General AO Project ID MTH0432.
[For.WLF2book2013] G. Fornaro, D. O. Nitti, R. Nutricato, F. Bovenga, D. Peduto, L. Cascini, "Methodological and Technological Advances in the Application of Spaceborne DInSAR for Landslide Monitoring". Proceeding of the the Second World Landslide Forum, published in Volume 2 "Early warning, instrumentation and monitoring" of the Springer Book Series for WLF2 "Landslide science and practice", pp. 379-384, Springer-Verlag Berlin Heidelberg 2013. ISBN 978-3-642-31444-5. DOI: 10.1007/978-3-642-31445-2_49. Scopus: 2-s2.0-84898059923.
Differential Interferometry Synthetic Aperture Radar is a mature remote sensing technique broadly used for the measurement of slow deformations with major application in several fields. In the last years, the application to slow moving landslides has grown quickly and several examples of the monitoring capability can be found in the literature. Main goal of this work is the description of the advances in terms of products that can be achieved from both an innovative methodological approach to DInSAR data analysis and the technological improvements related to the last generation of sensors.
ENVISAT and COSMO-SkyMED images on Ivancich test case were provided respectively by ESA and ASI in the framework of the MORFEO project (ASI Contract n. I/045/07/0).
[Was.EUROCK2013] J. Wasowski, F. Bovenga, D. Nitti, R. Nutricato, "Monitoring unstable slopes using Persistent Scatterers Interferometry: opportunities and challenges". Proceedings of Eurock 2013 ISRM International Symposium, Wroclaw, Poland, September 21-26, 2013. In book: Rock Mechanics for Resources, Energy and Environment - Kwasniewski and Lydzba (eds), pp. 713-717, (c) 2013 Taylor and Francis Group, London, ISBN 978-1-138-00080-3.
Advanced space-borne Persistent Scatterers Interferometry (PSI) can provide wide-area coverage (thousands km2) and precise (mm-cm resolution), spatially dense information (from hundreds to over thousand measurement points/km2) on ground surface deformations. Furthermore, new application opportunities are emerging thanks to i) the greater data availability offered by recent launches of radar satellites, ii) the improved capabilities of the new space radar sensors (Cosmo-SkyMed, TerraSAR-X) in terms of resolution (from 3 to 1 m) and revisit time (from 11 to 4 days). Although, the applicability of radar interferometry to regional and local-scale investigations of slope instability have been demonstrated in several studies, more progress is needed in the integration of PSI results with ground data and in their validation in order to foster a more profitable use of this technique. It is also expected that numerical modeling slope deformations detected by radar satellites should help to constrain the data interpretation.
Work supported in part by the Italian Space Agency (ASI) - COSMO-SkyMed AO Project ID 1820. ENVISAT and COSMO-SkyMed data were provided, respectively, by the European Space Agency (ESA) under CAT-1 project ID 2653 and by ASI.
[Bov.IGARSS2013] F. Bovenga, F. Rana A. Refice, D.O. Nitti, N. Veneziani, "Frequency coherent vs. temporally coherent targets". IEEE International Geoscience and Remote Sensing Symposium, July 21-26, 2013, Melbourne (Australia). ISSN 2153-6996. Print ISBN: 978-1-4799-1114-1. DOI: 10.1109/IGARSS.2013.6721103. SCOPUS: 2-s2.0-84894235469
The Multi-Chromatic Analysis (MCA) uses interferometric pairs of SAR images processed at range sub-bands and explores the phase trend of each pixel as a function of the different central carrier frequencies. The MCA technique introduces the concept of targets exhibiting stable radar returns across the frequency domain (PSfd). In this work we compare this stability along frequencies with the temporal stability which is at the base of persistent scatterers interferometry (PSI) techniques. Different populations of PSfd and “temporal” PS were derived by using COSMOSkyMed SAR data. An ad hoc processing scheme was developed to derive PSI products by processing the same range sub-bandwidth used by the MCA in order to guarantee the same scattering conditions. The populations of PSfd and “temporal” PS were compared and preliminary considerations provided concerning the scattering properties of the targets selected by the two criteria.
Work supported by both ASI Contr. N I/047/09/0, and ESA ESTEC Contr. N. 21319/07/NL/HE. COSMO/SkyMed data provided by ASI under the AO-COSMO Project ID-1820.
[Nut.SPIE2013] R. Nutricato, D. O. Nitti, F. Bovenga, A. Refice, J. Wasowski, M. T. Chiaradia, "C/X-band SAR interferometry applied to ground monitoring: examples and new potentials". Proc. SPIE 8891, SAR Image Analysis, Modeling, and Techniques XIII, 88910C (October 17, 2013); doi:10.1117/12.2029096. ISSN: 0277-786X. ISBN: 9780819497604. Scopus: 2-s2.0-84889063441. WOS:000327079900009
Classical applications of the MTInSAR techniques have been carried out in the past on medium resolution data acquired by the ERS, Envisat (ENV) and Radarsat sensors. The new generation of high-resolution X-Band SAR sensors, such as TerraSAR-X (TSX) and the COSMO-SkyMed (CSK) constellation allows acquiring data with spatial resolution reaching metric/submetric values. Thanks to the finer spatial resolution with respect to data, X-band InSAR applications result very promising for monitoring single man-made structures (buildings, bridges, railways and highways), as well as landslides. This is particularly relevant where data show low density of coherent scatterers. Moreover, thanks again to the higher resolution, it is possible to infer reliable estimates of the displacement rates with a number of SAR scenes significantly lower than in within the same time span or by using more images acquired in a narrower time span. We present examples of the application of a Persistent Scatterers Interferometry technique, namely the SPINUA algorithm, to data acquired by ENV, TSX and CSK on selected number of sites. Different cases are considered concerning monitoring of both instable slopes and infrastructure. Results are compared and commented with particular attention paid to the advantages provided by the new generation of X-band high resolution space-borne SAR sensors.
Work supported by the project “Landslide Monitoring and Mapping System - CAR-SLIDE” (PON 01 00536). TerraSAR-X data are provided by DLR in the frame of the TerraSAR-X General AO Projects MTH0432. CSK data are provided by ASI (Agenzia Spaziale Italiana) in the framework of the CAR-SLIDE (PON 01 00536) project. ENVISAT data are provided by ESA under CAT-1 project ID 2653.
[Nit.SPIE2013] D. O. Nitti, F. Bovenga, R. Nutricato, F. Intini, M. T. Chiaradia, "DEM generation by using COSMO-SkyMed tandem pairs and Weather Models". Proc. SPIE 8891, SAR Image Analysis, Modeling, and Techniques XIII, 88910E (October 17, 2013); doi:10.1117/12.2048902. ISSN: 0277-786X. ISBN: 9780819497604. Scopus: 2-s2.0-84889031791. WOS:000327079900011
The paper investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement through conventional and multi-temporal SAR Interferometry (InSAR), with particular attention devoted to the impact of the improved spatial resolution with respect to the previous SAR sensors. The Atmospheric Phase Screen (APS) is wellknown to be the main source of errors for accurate topographic mapping through SAR interferometry, in case of monostatic sensors. Different strategies can be adopted to filter out this signal, ranging from the exploitation of the wellknown spatial and temporal statistics of the APS to the estimation of independent APS measurements through Numerical Weather Prediction (NWP) models. Their feasibility and the achievable accuracies are discussed here.
Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the project “AO- COSMO Project ID-1462 - Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation - ASI Contract I/063/09/0”. Authors would like to thank Rosa Pacione (eGEOS/ASI-CGS) and Francesco Vespe (ASI/CGS) for the fruitful collaboration and GPS Zenith Total Delay (ZTD) data provided.
[Bar.EWRA2013] E. Barca, G. Passarella, M. Vurro, A. Morea, "Optimal redesign of groundwater monitoring networks: a data-driven, multi-approach software". Proceedings of 8th International Conference of EWRA "Water Resources Management in an Interdisciplinary and Changing Context", Porto, Portugal, 26th-29th June 2013. ISBN: 978-989-95557-8-5
Within recent WFD and the modification introduced into national water related legislation, monitoring assumes great importance in the frame of territorial managerial activities. Recently, a number of public environmental agencies invested resources in planning improvements on existing monitoring networks. A lot of reasons justify the optimal redesign of a monitoring network. In fact, a modest or sparse coverage of the monitored area or redundancies and clustering of monitoring locations often make impossible to provide the manager with a sufficient knowledge for decision-making processes. These are typical cases requiring an optimal redesign of the whole network; particular emphasis shall be devoted to quality groundwater monitoring network. Using reliable stochastic or deterministic methods, it is possible to rearrange the existing network by eliminating, adding or moving monitoring locations producing the most uniform arrangement among any possible. In this paper, some spatial optimization methods have been selected as more effective among those reported in literature and implemented in a software able to carry out a complete redesign of an existing monitoring network. Both stochastic and deterministic methods have been embedded in the software with the option of choosing, case by case, the most suitable with regard to the available information. Finally, an application to the existing regional groundwater level monitoring network of the aquifer of Tavoliere located in Apulia (South Italy) is presented.
[Ref.Earsel2013] A. Refice, G. Pasquariello, A. D’Addabbo, F. Bovenga, R. Nutricato, D. Capolongo, A. Lepera, L. Pietranera, S. Manfreda, A. Cantisani, A. Sole, "Inundation monitoring through high-resolution SAR/InSAR data and 2D hydraulic simulations". Proceedings of 33th EARSeL Symposium, Towards Horizon 2020: Earth Observation and Social Perspectives, Matera (Italy), 3 - 6 June 2013, pp. 15-22. Editors: R. Lasaponara, N. Masini, M. Biscione, CNR, Italy. ISBN: 978-88-89693-34-6.
In the present paper, COSMO-SkyMed high-resolution data acquired on the southern Basilicata region (Italy) are used for flood hazard monitoring. We concentrate on the flood event of Nov. 2-4, 2010, for which multi-temporal SAR data were available over the Bradano River downstream area in the same acquisition geometry, which allows interferometric processing. SAR intensity data analysis of two acquisitions dated 3 and 4 Nov., performed through optimized thresholding algorithms, shows good results, highlighting the temporal evolution of the flood throughout the two days, as also confirmed by a comparison with the results of a 2D hydraulic simulation of the same event. Additional use of the one-day co-event coherence channel, and then of more intensity and coherence data layers in the multi-temporal dataset, through automated clustering procedures, helps discriminating in more detail some uncertain cases regarding inundated fields, and suggest procedures to shed light on the spatio-temporal backscattering patterns of flood-prone areas.
COSMO-SkyMed data were courtesy of e-Geos s.p.a. The authors thank Dr. Ing. D. O. Nitti, of Geophysical Application Processing s.r.l., for the InSAR data processing.
Conference Abstracts
[Nit.AGU2013] D. O. Nitti, M. T. Chiaradia, R. Nutricato, F. Bovenga, A. Refice, M. F. Bruno, E. Ciracì, A. F. Petrillo, L. Guerriero, "On the use of Numerical Weather Models for improving SAR geolocation accuracy (ID: 1795652)". AGU Fall Meeting 2013 Abstract, G31A-0935, San Francisco, California, USA, 9-13 Dec. 2013. http://abstractsearch.agu.org/meetings/2013/FM/sections/G/sessions/G31A/abstracts/G31A-0935
Precise estimation and correction of the Atmospheric Path Delay (APD) is needed to ensure sub-pixel accuracy of geocoded Synthetic Aperture Radar (SAR) products, in particular for the new generation of high resolution side-looking SAR satellite sensors (TerraSAR-X, COSMO/SkyMED). The present work aims to assess the performances of operational Numerical Weather Prediction (NWP) Models as tools to routinely estimate the APD contribution, according to the specific acquisition beam of the SAR sensor for the selected scene on ground. The Regional Atmospheric Modeling System (RAMS) has been selected for this purpose. It is a finite-difference, primitive equation, three-dimensional non-hydrostatic mesoscale model, originally developed at Colorado State University [1]. In order to appreciate the improvement in target geolocation when accounting for APD, we need to rely on the SAR sensor orbital information. In particular, TerraSAR-X data are well-suited for this experiment, since recent studies have confirmed the few centimeter accuracy of their annotated orbital records (Science level data) [2]. A consistent dataset of TerraSAR-X stripmap images (Pol.:VV; Look side: Right; Pass Direction: Ascending; Incidence Angle: 34.0÷36.6 deg) acquired in Daunia in Southern Italy has been hence selected for this study, thanks also to the availability of six trihedral corner reflectors (CR) recently installed in the area covered by the imaged scenes and properly directed towards the TerraSAR-X satellite platform. The geolocation of CR phase centers is surveyed with cm-level accuracy using differential GPS (DGPS). The results of the analysis are shown and discussed. Moreover, the quality of the APD values estimated through NWP models will be further compared to those annotated in the geolocation grid (GEOREF.xml), in order to evaluate whether annotated corrections are sufficient for sub-pixel geolocation quality or not. Finally, the analysis will be extended to a limited number of COSMO/SkyMED data available over the area of interest in order to achieve preliminary indications on the quality of orbital records for the latter X-band constellation.
TSX data provided by DLR under the TerraSAR-X General AO Project MTH0432. CSK data provided by ASI under the AO-COSMO Project ID-1462. This work has been partially funded by MIUR in the framework of the project CAR-SLIDE (PON01_00536).
[Nut.AGU2013] R. Nutricato, J. Wasowski, M.T. Chiaradia, B. E. Piard, P. Mondesir, "Multi-temporal interferometric monitoring of ground deformations in Haiti with COSMO/SkyMed HIMAGE data (ID: 1808199)". AGU Fall Meeting 2013 Abstract, NH13A-1589, San Francisco, California, USA, 9-13 Dec. 2013.
The catastrophic Mw=7.0 shallow earthquake of 12 January 2010 that struck Haiti have led to numerous studies focused on the geodynamics of the region. In particular, the co-seismic fault mechanism of the 2010 Haiti earthquake as well as post-seismic deformations have been investigated through SAR interferometry (InSAR) techniques, thanks to the availability of satellite SAR sensors operating in different radar bands (ENVISAT ASAR, ALOS PALSAR, TerraSAR-X, COSMO/SkyMed). Moreover, advanced multitemporal SAR interferometry (MTI) based on COSMO/SkyMED (CSK) data is well suited for the detection and monitoring of post-seismic ground or structural instabilities. Indeed, with its short revisit time (up to 4 days) CSK allows building interferometric stacks much faster than previous satellite missions, like ERS/ENVISAT. Here we report the first outcomes of the MTI investigation based on high resolution (3 m) CSK data, conducted in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS) of Haiti and the Department of Physics (DIF) of the University of Bari, Italy. We rely on a stack of 89 CSK data (image mode: HIMAGE; polarization: HH; look side: right; pass direction: ascending; beam: H4-0A) acquired by the Italian Space Agency (ASI) over the Port-au-Prince (PaP) metropolitan and surrounding areas that were severely hit by the 2010 earthquake. CSK acquisitions span the period June 2011 ÷ February 2013, which is sufficient for detecting and monitoring significant ground instabilities. The MTI results were obtained through the application of the SPINUA processing chain, a Persistent Scatterers Interferometry (PSI)-like technique. In particular, we detected significant subsidence phenomena affecting river deltas and coastal areas of the PaP and Carrefour region. The maximum rate of subsidence movements exceed few cm/yr and this implies increasing flooding (or tsunami) hazard. Furthermore, maximum subsidence rates were encountered in areas with high population density and this translates into high potential risk. The MTI results also revealed the presence of very slow slope movements and local ground / structure instabilities. Some of these may have been initially triggered by the 2010 event. Elsewhere the MTI-detected displacements can be related to the presence of poorly constructed buildings. This case study demonstrates that MTI represents a very good option for the assessments of ground / structure instability in regions that lack in situ monitoring data. In view of this the results of this study will be transferred to the Civil Protection of Haiti.
CSK images provided by ASI (Agenzia Spaziale Italiana) in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS) of Haiti and the Department of Physics (DIF) of the University of Bari, Italy. The authors would like to thank Aldo Giovacchini (Consorzio ITA), Fabio Bovenga (CNR-ISSIA), D.O. Nitti (GAP Srl) and E. Ciracì (UCI) for helpful contributions to the achieved results.
[Pre.PhDXXIII] G. Preziosa, "ANTENNE PLANARI PER MICROONDE — TEORIA E REALIZZAZIONE". PhD Thesis, Scuola Dottorato di Ricerca in Fisica XXIII Ciclo, Dipartimento Interateneo di Fisica "M. Merlin", Università degli Studi di Bari Aldo Moro. Tutor: Prof. F. Posa (DIF-BA). Coordinatore: Prof. F. Romano (DIF-BA). SSD: FIS/01
L'elettronica per le alte frequenze, generalmente suddivise in radiofrequenze (RF), microonde e onde millimetriche, è stata oggetto di rinnovato interesse negli ultimi anni grazie alla notevole diffusione delle comunicazioni senza fili con frequenze di impiego oltre il GHz, nonch´e al sempre maggiore interesse destato da applicazioni scientifiche d'alto profilo quali l'osservazione della Terra e degli altri pianeti con l'utilizzo di sistemi radar. L'impiego delle microonde per le applicazioni di telerilevamento (remote sensing) con sensori orbitanti ha avuto inizio nei primi anni '60, affiancando la fotografia aerea in bianco e nero e a colori già in uso da tempo, e i cui eccellenti risultati in termini di qualità, utilità, perfezione tecnica raggiunta, erano ben noti. Perchè allora usare le microonde? Questa domanda ha varie risposte. Forse la ragione più importante risiede nella loro capacità di penetrare le nuvole (e fino a un certo punto anche la pioggia), e nella raggiunta, desiderata indipendenza dall'illuminazione solare. Un'altra ragione per l'utilizzo della radiazione a microonde è che questa riesce a penetrare più in profondità nella vegetazione e anche nei suoli, con dipendenza dal contenuto di umidità e dalla lunghezza d'onda; le onde più lunghe hanno penetrazione maggiore rispetto alle più corte, quindi le prime tenderanno a fornire informazioni sulla vegetazione massiva e sugli strati profondi del suolo, le seconde invece sugli strati superficiali della vegetazione e del suolo. Una terza valida ragione per l'uso delle microonde è semplicemente che l'informazione disponibile con le microonde è diversa da quella ottenibile nelle regioni ottiche e dell'infrarosso, perch´e ciascun oggetto sotto osservazione ha una peculiare risposta alla radiazione di diversa frequenza, dovuta principalmente alle risonanze molecolari del materiale di cui è composto. Nell'arco degli ultimi anni, inoltre, la realizzazione dei circuiti elettronici e delle antenne per le alte frequenze, che prima si configurava come un complicato esercizio per iniziati o espertissimi, è stata in larga parte semplificata dall'avvento di strumenti di Computer Aided Design (CAD) che hanno reso possibile un avvicinamento piu rapido e preciso al progetto. Ovviamente resta il fatto che le tecniche di analisi e sintesi per l'elettronica RF e delle microonde sono sempre peculiari per la presenza di elementi distribuiti, di componenti attivi poco convenzionali, e di tecniche di realizzazione facenti uso di materiali sofisticati e spesso innovativi. Il presente lavoro focalizza l'attenzione su un particolare tipo di antenne per microonde: le antenne planari, così chiamate per il loro aspetto piatto e sottile. Si tratta di antenne realizzate a partire da lastre dielettriche di piccolo spessore rivestite con materiale conduttore, la cui forma opportuna viene ottenuta secondo la tecnica dei circuiti stampati. Ci si propone di progettare e costruire sei coppie di antenne planari operanti nelle tre bande a microonde denominate L, C ed X, costruite in modo da avere a disposizione due coppie di antenne per ciascuna banda: una coppia realizzata con laminato dielettrico di alta qualità a base ceramica specificamente adatto allo scopo, l'altra coppia realizzata invece con laminato standard in fibra di vetro denominato FR4 e tipicamente meno adatto per l'utilizzo nel campo delle microonde. In tal modo è possibile verificare se il laminato FR4, pur essendo meno esotico rispetto a quello ceramico, possa comunque consentire risultati degni di nota, qualora nella fase di progettazione si abbia cura di determinare con sufficiente accuratezza i suoi parametri dielettrici. La sintesi delle antenne viene affrontata con l'ausilio di sistemi CAD e secondo una metodologia nuova rispetto a quelle consuete. Poich´e ciascun prototipo è realizzato in coppia (due antenne identiche), oltre alle consuete misure dei parametri risonanti diviene possibile eseguire misure con la tecnica di Friis, cioè con le antenne gemelle che si guardano vicendevolmente, e misure in modalità bistatica, cioè con l'antenna ricevente distinta da quella trasmittente, adoperando un bersaglio di nota sezione d'urto radar. Dopo un doverosa trattazione della teoria elettromagnetica che regola tutta la materia e dalla quale non si può prescindere, con particolare attenzione alle linee di trasmissione di tipo planare come le microstrip, si passa alla descrizione dei parametri peculiari delle antenne, ovvero quei parametri che sono oggetto di valutazione nelle fasi progettuali, e di misura sui prototipi realizzati. Segue la descrizione approfondita delle antenne di tipo planare, includendo sia i modelli teorici di analisi e sintesi che le svariate tecniche di alimentazione. Vengono quindi presentati i prototipi realizzati, motivando le scelte progettuali e illustrando le procedure di fabbricazione, assemblaggio e sintonizzazione finale. Le misure sulle antenne costruite sono condotte con l'ausilio di un analizzatore vettoriale di reti ed altri strumenti tipici del laboratorio per microonde. Infine si presentano alcune considerazioni sui risultati raggiunti e sulle interessanti prospettive di lavoro futuro.
[Bov.RSE2012] F. Bovenga, J. Wasowski, D. O. Nitti, R. Nutricato, M. T. Chiaradia, "Using Cosmo/SkyMed X-band and ENVISAT SAR Interferometry for landslide analysis". Remote Sensing of Environment - 2012, 119: 272-285. DOI: 10.1016/j.rse.2011.12.013. ISSN: 0034-4257. WOS:000301892200025. Scopus: 2-s2.0-84856086628. IF: 5.103 (Year: 2012 - Source: ResearchGate - http://is.gd/L3bzT5)
We explore new possibilities offered by the recently available X-band satellite radar sensors for landslide hazard assessments on a detailed scale, with particular reference to the exploitation of Persistent Scatterers Interferometry (PSI) techniques. Special attention is paid to the impact of the improved resolution of new Xband radar imagery on the PSI results, in terms of quality and quantity of useful information. This evaluatiois supported by theoretical modelling as well as by the comparison of results from X-band (CSK) and C-ban(ENVISAT) PSI for two areas of interest: one in Italy and the other in Switzerland. It is demonstrated that with respect to medium resolution ENVISAT PS processing, fewer CSK high resolution images are sufficient to achieve comparable precision of the mean displacement velocity estimates. This, together with the shorter revisit times provided by the CSK constellation, can be very important when dealing with emergency situations. Furthermore, it is quantified that from about 3 to 11 times greater PS densities are obtained with the higher resolution X-band data. This implies more information about ground surface displacements as well as improved landslide monitoring and slope instability investigation capabilities. Furthermore, ground displacement measurements can be interpreted without local knowledge of the focus area or in situ controls, and, nonetheless, guide single hillslope instability assessments with support of Google Earth and its high resolution optical imagery. This “blind” approach will allow one to monitor remote and poorly known regions at high risk of potentially disastrous slope failures.
The work has been in part supported by the MORFEO project funded by the Italian Spatial Agency (ASI) (ASI Contract n. I/045/07/0). ENVISAT and COSMO-SkyMED data were provided respectively by ESA and ASI in the framework of the MORFEO project. We thank three anonymous reviewers for their very helpful comments.
[Cza.PGR2012] M. Czarnogórska, M. Graniczny, S. Uoecinowicz, R. Nutricato, S. Triggiani, D. O. Nitti, F. Bovenga, J. Wasowski, “Ground deformations along SW coast of the Gulf of Gdañsk analysed using satellite radar interferometry”. Przeglad Geologiczny (Polish Geological Review), vol. 60, nr 3, 2012. ISSN-0033-2151. Scopus: 2-s2.0-84862733602. IF: 0.186 [2-years Cites per Doc] (Year: 2012 - Source: SJR - http://is.gd/BXi24r)
The paper presents results of SPINUA (Stable Point Interferometry over Unurbanised Areas) Persistent Scatterers Interferometry (PSI) processing chain to study Earth surface deformations along the SW coast of the Gulf of Gdañsk, along the SE part of the Baltic Sea. As the input for SPINUA techniques 40 descending ERS-1/2 SLC (Frame = 251, Track = 36) images from the period 1995–2001 has been used. The area of interest (AOI) includes few cities and several towns, villages and harbors. The low lying coastal areas of the SW part of the Gulf of Gdañsk are at risk of floods and marine erosion. The PSI results, however, did not reveal the presence of a regional scale, spatially consistent pattern of displacements. It is likely that any crustal deformations in the AOI simply do not exceed ±2 mm/year, which is the velocity threshold we assumed to distinguish between moving and non-moving persistent scatterers (PS). Importantly, for the most part the urban areas of the main cities (Gdañsk, Gdynia and Sopot) results show ground stability. Nevertheless, significant downward movements up to several mm/year, are locally noticed in the Vistula river delta – alluvial plain system located in the coastal zone east of Gdañsk as well as in the inland area west of the Gdañsk city. Indeed, the highest subsidence rates (–12 mm/year) was observed in the Gdañsk petroleum refinery constructed on alluvial sediments. Thus the anthropogenic loading and consolidation of the recent deposits can locally be an important factor causing ground subsidence.
[Ber.HARTES2012] K. Bertels, A. Lattanzi, E. Ciavattini, F. Bettarelli, M. T. Chiaradia, R. Nutricato, A. Morea et al., "The hArtes Tool Chain". In book: “Hardware/Software Co-design for Heterogeneous Multi-core Platforms”, edited by K. Bertels, published 2012 by Springer, pp. 9-109. ISBN 978-94-007-1405-2. e-ISBN 978-94-007-1406-9. DOI 10.1007/978-94-007-1406-9.
The hArtes project1 was started as an innovative European project (funded by European Union) aiming at laying the foundations of a new holistic approach for the design of complex and heterogeneous embedded solutions (hardware and software), from the concept to the silicon (or B2B, from the brain to bits). The hArtes stands for “holistic Approach to reconfigurable real time embedded systems”. As defined in the Embedded Systems Chapter of the IST 2005-06 Work Programme the objective of the hArtes project is to “develop the next generation of technologies, methods and tools for modeling, design, implementation and operation of hardware/software systems embedded in intelligent devices. An end-to-end systems (holistic) vision should allow building cost-efficient ambient intelligence systems with optimal performance, high confidence, reduced time to market and faster deployment”. The hArtes project aims to lay the foundation for a new holistic (end-to-end) approach for complex real-time embedded system design, with the latest algorithm exploration tools and reconfigurable hardware technologies. The proposed approach will address, for the first time, optimal and rapid design of embedded systems from high-level descriptions, targeting a combination of embedded processors, digital signal processing and reconfigurable hardware. The project ended with an important scientific and technical contribution that resulted in more than 150 international publications as well as a spin-off company, BlueBee.2 From the application point of view, the complexity of future multimedia devices is becoming too big to design monolithic processing platforms. This is where the hArtes approach with reconfigurable heterogeneous systems becomes vital. As a part of the project, a modular and scalable hardware platforms will be developed that can be reused and re-targeted by the tool chain to produce optimized real-time embedded products. The results obtained will be evaluated using advanced audio and video systems that support next-generation communication and entertainment facilities, such as immersive audio and mobile video processing. Innovations of the hArtes approach include: (a) support for both diagrammatic and textual formats in algorithm description and exploration, (b) a framework that allows novel algorithms for design space exploration, which aims to automate design partitioning, task transformation, choice of data representation, and metric evaluation for both hardware and software components, (c) a system synthesis tool producing near optimal implementations that best exploits the capability of each type of processing element; for instance, dynamic reconfigurability of hardware can be exploited to support function upgrade or adaptation to operating conditions.
This book describes the outcome of the hArtes project (IST-035143) supported by the Sixth Framework Programme of the European Community under the thematic area Embedded Systems.
International Conference Proceedings
[Was.ISL2012] J. Wasowski, F. Bovenga, Nitti D, R. Nutricato (2012). Investigating landslides with Persistent Scatterers Interferometry (PSI): current issues and challenges. In: (a cura di): Erik Eberhardt, Corey Froese, Keith Turner, S. Leroueil, Landslides and Engineered Slopes: Protecting Society through Improved Understanding. VOLUME 2: Simulating and managing rock fall. Proceedings of the 11th International and 2nd North American Symposium on Landslides and Engineered Slopes. vol. 2, p. 1295-1301, CRC press, Taylor and Francis Group., ISBN: 978-0415621236.
Examples of slope and associated infrastructure instability assessments by PSI are presented to highlight current application opportunities related to i) the greater data availability offered by recent launches of radar satellites and ii) the improved capabilities of the new space-borne radar sensors (e.g. Cosmo-SkyMed, TerraSAR-X) in terms of resolution (from 3 to 1 m) and revisit time (from 11 to 4 days). Attention is drawn to the main factors that limit the general applicability of PSI in landslide investigations, to the difficulties in inferring the exact cause(s) of very slow displacements (mm-cm/ year) commonly registered on radar targets and to the risks of misinterpretation. Specific recommendations and guidelines are offered on how to mitigate PSI limitations and avoid erroneous interpretations. The utility of Google EarthTM tools for 3D visualization and preliminary reconnaissance analysis of PSI results is also emphasized.
Our efforts were in part supported by the Italian Space Agency (ASI) - Contract I/045/07/0. ENVI-SAT and TerraSAR-X data were provided, respec-tively, by the European Space Agency (ESA) under CAT-1 project ID 2653 and by the German Space Agency (DLR) under TerraSAR-X General AO Pro-ject ID MTH0432.
[Rad.FIG2012] F. Radicioni, A. Stoppini, G. Fornaro, F. Bovenga, D. O. Nitti, "Long-Term GNSS and SAR Data Comparison for the Deformation Monitoring of the Assisi Landslide". Proceedings of the FIG Working Week 2012 - Knowing to manage the territory, protect the environment, evaluate the cultural heritage. Rome, Italy, 6-10 May 2012. ISBN 97887-90907-98-3.
A relevant part of the Assisi urban area (central Italy), built up after 1950 and located outside of the ancient town center, is interested by a landslide characterized by a slow rate of movement, which has caused important damages to buildings for an accumulation effect in time. The movements of the soil surface have both a horizontal and a vertical component. A GNSS network for deformation monitoring purposes has been established over the area since 1995, connecting by means of a baseline network the moving region with stable geologic formations located well outside of the landslide body. Further (1999), a leveling network has been added to improve the definition of the vertical component of the motion field. Surveys of both GNSS and leveling networks have been carried out in time, with an approximately annual cadence, until the actuality. Time series of coordinates and heights spanning along the observation period (1995-2010) are hence available for the network points. The Assisi landslide area has also been investigated by means of satellite SAR interferometry InSAR: the data here presented derive from the analysis of ENVISAT ASAR data spanning in time from 2003 to 2010, thus with a 7-years overlapping with the GNSS and leveling surveys, which make possible a comparison. The comparison has been made for each GNSS marker with the surrounding InSAR scatters, trying to take into account local topological effects when possible. A good agreement between the results of the different techniques has been found in most cases, and a deeper analysis of the movement field and the landslide edge is derived from the complete set of data.
We thank the Provveditorato alle Opere Pubbliche per la Toscana e l’Umbria for funding the monitoring activity on the Assisi landslide.
[Nit.IGARSS2012] D. O. Nitti, F. Bovenga, R. Nutricato, F. Intini, M. T. Chiaradia, R. Pacione, F. Vespe, "On the use of COSMO-SkyMed SAR data and Numerical Weather Models for interferometric DEM generation". Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 22-27, 2012. Munich, Germany. DOI: 10.1109/IGARSS.2012.6350551. ISSN: 2153-6996. eISSN: 2153-7003. E-ISBN : 978-1-4673-1158-8. Print ISBN: 978-1-4673-1160-1. Scopus: 2-s2.0-84873191384. WOS:000313189404012
The present study is aimed at investigating the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. Assuming no movement and successful orbital error removal, the main problem in height computation through InSAR techniques derives from the interferometric phase artifacts related to the interaction between microwave and the lower layers of the atmosphere (APS, Atmospheric Phase Screen). Different strategies can be adopted to filter out this signal, ranging from the exploitation of the well-known spatial and temporal statistics of the APS to the estimation of independent APSmeasurements through Numerical Weather Prediction (NWP) models. Their feasibility and the achievable accuracies are discussed here.
Work supported by ASI in the framework of the AO Projects ID-1462 “Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation” (Contract n. I/063/09/0) and ID-2103 “Advanced 2D and 3D focusing of COSMO/SkyMed SAR data” (Contract n. I/059/09/0). GPS data analyzed by e-GEOS under ASI contract I-014-10-0.
[Chi.IGARSS2012] M. T. Chiaradia, G. Fornaro, A. Freni, G. Franceschetti, P. Imperatore, F. Intini, A. Iodice, A. Mori, D. O. Nitti, R. Nutricato, D. Reale, D. Riccio, P. Trivero. "COSMO/SkyMed AO Projects – Advanced 2D and 3D focusing of COSMO/SkyMed SAR data". Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 22-27, 2012. Munich, Germany. DOI: 10.1109/IGARSS.2012.6352603. ISSN : 2153-6996. eISSN: 2153-7003. E-ISBN : 978-1-4673-1158-8. Print ISBN: 978-1-4673-1160-1. Scopus: 2-s2.0-84873160925. WOS:000313189406192
We present a research project, funded by the Italian Space Agency (ASI), aimed at performing 2D and 3D Focusing of COSMO/SkyMed (CSK) SAR Data. We describe the main objectives of the project, briefly illustrate employed techniques, and finally present the obtained results. The latter show that sub-meter resolution can be achieved in the enhanced spotlight CSK acquisition mode, and that by using 3D focusing it is possible to resolve scatterers at different slant heights within the same range-azimuth resolution cell, even in areas characterized by severe height discontinuities and large thermal dilations effects.
Work funded by ASI within the COSMO/SkyMed Announcement of Opportunity ("Advanced Focusing of COSMO/SkyMed Data", ID 2103).
[Bov.IGARSS2012] F. Bovenga, F. Rana, A. Refice, D. O. Nitti, N. Veneziani. "Interferometric multi-chromatic analysis of COSMO-SkyMed data for height retrieval". Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 22-27, 2012. Munich, Germany. DOI: 10.1109/IGARSS.2012.6350579. ISSN: 2153-6996. eISSN: 2153-7003. E-ISBN: 978-1-4673-1158-8. Print ISBN: 978-1-4673-1160-1. Scopus: 2-s2.0-84873184555. WOS:000313189403240.
The Multi-Chromatic Analysis can be applied to interferometric pairs of SAR images processed at range subbands, and consists of exploring the phase trend of each pixel as a function of the different central carrier frequencies. The phase of stable scatterers evolves linearly with the sub-band central wavelength, with a slope proportional to the absolute e.m. path difference. The technique appears optimally suited for the new generation of satellite sensors, which operate with larger bandwidths than previously available instruments, generally limited to few tens of MHz. A first experiment on satellite data was carried out by processing a spotlight interferometric pair of images acquired by TerraSAR-X on the well-known Uluru monolith in Australia. In the present work, we illustrate MCA processing on SAR data acquired over the same site by the COSMO-SkyMed constellation. The topographic profile of the monolith is successfully reconstructed. Furthermore, the results are also compared with those previously derived by processing TerraSAR-X data.
Work supported by ASI under the AO-COSMO Project ID-1820, Contr. N I/047/09/0.
[Nit.SPIE2012] D. O. Nitti, F. Bovenga, A. Morea, F. M. Rana, L. Guerriero, M. Greco, G. Pinelli, "On the use of SAR interferometry to aid navigation of UAV". Proc. SPIE 8532, Remote Sensing of the Ocean, Sea Ice, Coastal Waters, and Large Water Regions 2012, 853203 (October 19, 2012). DOI:10.1117/12.974563. ISSN: 0277-786X. ISBN: 9780819492722. Scopus: 2-s2.0-84887047598. WOS:000312874500003
This study is aimed at exploring the potentials of SAR Interferometry (InSAR) to aid Unmanned Aerial Vehicles (UAV) navigation. The basic idea is to infer both position and attitude of an aerial platform by inspecting the InSAR phase derived by a real time SAR interferometer mounted onboard the platform. Thanks to the expected favorable conditions in terms of geometrical sensitivity as well as signal coherence, the InSAR phase field can be used to derive the terrain elevation. By using both approximated position and attitude values of the platform as well as a reference Digital Terrain Model (DTM) from a mission database available onboard, it is possible to generate a synthetic InSAR phase model to be compared w.r.t. that derived by SAR observations. The geometrical transformation needed to match these two terrain models depends on the difference between position and attitude values derived by the instruments available on board and their actual values. Hence, this matching provides a feedback to be used for adjusting position and attitude. In order to assess the reliability of the proposed approach, we evaluated the interferometric sensitivity to changes in position and attitude. This analysis defines the limits of applicability of the InSAR-based approach and provides indications and requirements on geometric and radiometric parameters.
The authors acknowledge the support of the SARINA project A-0932-RT-GC, which is coordinated by the European Defence Agency (EDA) and funded by 10 contributing Members (Cyprus, France, Germany, Greece, Hungary, Italy, Norway, Poland, Slovakia, Slovenia and Spain) in the framework of the Joint Investment Programme on Innovative Concepts and Emerging Technologies (JIP-ICET).
[Bov.SPIE2012] F. Bovenga, L. Gallitelli, D. O. Nitti, "Multi-chromatic analysis of a single SAR image for absolute ranging". Proc. SPIE 8536, SAR Image Analysis, Modeling, and Techniques XII, 853604 (November 21, 2012); DOI:10.1117/12.973722. ISSN: 0277-786X. ISBN: 9780819492760. Scopus: 2-s2.0-84875636236. WOS:000317134300003
The Multi-Chromatic Analysis (MCA) uses interferometric pairs of SAR images processed at range sub-bands located at different spectrum positions, and explores the phase trend of each pixel in the frequency domain. The phase of stable scatterers evolves linearly with the sub-band central wavelength, the slope being proportional to the absolute optical path difference. Consequently, both phase uwrapping and height computation can be performed on a pixel by pixel basis without spatial integration. Recently the technique has been used to derive ground elevation by processing interferometric pairs acquired in Spotlight mode by both TerraSAR-X and COSMO-SkyMed satellite missions. However, further potential applications are possible. In particular, this work is aimed at experimenting the use of MCA for measuring the optical path between the SAR sensor and the scene by processing a single SAR acquisition. In this configuration, the slope of the phase trend along frequencies depends on the full optical path. In order avoid aliasing, we adopted a processing scheme which consists in subtracting from the SAR image phase a term proportional to the distance computed through inverse geocoding. Assuming negligible the positioning errors, the validation of this approach can be performed by comparing the distance measured by MCA with the atmospheric delay computed through analytical models. We carried out a feasibility study aimed at evaluating the maximum value for the errors in satellite and target positions, allowed to perform the reliable validation. Then, in order to reduce the error in the target positions and to guarantee good phase stability, we selected SAR acquisitions which include artificial corner reflectors to be used for MCA processing and the following validation procedure. We present results obtained by exploiting two corner reflectors visible within two TerraSAR-X images acquired in Spotlight mode over Venice Lagoon.
TerraSAR-X data are provided by DLR (c) in the frame of the TerraSAR-X General AO Project MTH0432. Authors thank Davide Oscar Nitti from GAP srl to assist in gecoding processing.
[Rad.MIMOS2012] F. Radicioni, A. Stoppini, R. Brigante, G. Fornaro, F. Bovenga, D. O. Nitti, "InSAR, GNSS and leveling comparison on multi-annual series for the study of landslide surface deformation". Proceedings of MIMOS. October 9-11, 2012. Campus Universitario Tor Vergata, Roma. ISBN: 9788890764202 (presentation available at: http://lnx.mimos.it/mimos_decennale/Proceedings/SicurezzaTerritorio_08_Stoppini.pdf).
A relevant part of the Assisi urban area (central Italy), built up after 1950 and located outside of the ancient town center, is interested by a landslide characterized by a rather slow rate of movement, which has caused important damages to buildings for an accumulation effect in the years. The movements of the soil surface have both a horizontal and a vertical component. For the monitoring of the landslide behaviour, the determination of the motion field and its evolution in time, a precision GNSS network has been established over the area since 1995, connecting by means of a baseline network the moving area with stable geologic formations located well outside (up to some km distance) of the landslide body. Further (1999), a leveling network has been added to improve the definition of the vertical component of the motion field. Surveys of both GNSS and leveling networks have been carried out in time, with an approximately annual cadence, until the actuality. Time series of coordinates and heights spanning along the observation period (1995-2010) are hence available for the network points. The Assisi landslide area has also been investigated by means of InSAR: the data here presented derive from the analysis of Envisat data spanning in time from 2003 to 2010, thus with a 7-years overlapping with the GNSS and leveling surveys, which make possible a comparison. SAR data refer to scatter points which are numerous and well spread over the landslide area but almost never coinciding with the GNSS and leveling markers. Moreover, the type of movements which can be put into evidence are different: along an assigned direction (the LOS, Line Of Sight) from the SAR data, in 3 dimensions from GNSS, along the vertical direction from leveling. This paper presents a comparison of the SAR results with the GNSS data, from which the LOS component has been derived. The comparison has been made for each GNSS marker with the surrounding SAR scatters, trying to take into account local topological effects when possible. This paper also presents results of the comparison between InSAR and leveling data, which requires a different approach, considering the different one-dimensional components of the movement given by leveling (along the vertical) and InSAR (along the LOS)
[Ves.IGARSS2012] F. Vespe, L. Baldini, C. Benedetto, M. T. Chiaradia, C. Iasio, A. Losurdo, C. Notarnicola, C. Prati, D. Riccio, "X-SAR Cosmo-SkyMed mission and its scientific applications in the field of earth's observations: Some topics concerning the combinations of the observations achieved with other techniques". Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 22-27, 2012. Munich, Germany. DOI: 10.1109/IGARSS.2012.6352355. ISSN : 2153-6996. E-ISBN : 978-1-4673-1158-8. Print ISBN: 978-1-4673-1160-1.
The Italian Space Agency (ASI Agenzia Spaziale Italiana) funded 27 scientific projects in the framework of COSMOSkyMed (CSK) program. A subset of them focused on the improvements of the quality and quantity of information which can be extracted from X-SAR data if integrated with other independent techniques (GPS, data and imagery in other bands and wavelengths). The paper summarizes the results obtained from same of these projects and, in particular, regarding: (1) the use of GPS observations and Numerical Weather Models (NWM) to remove atmospheric artifacts from InSAR imagery so improving the CSK potentialities in the field of topographic mapping; (2) the integration of SAR data in X, L and s to improve snow cover monitoring and glaciers detection; (3) the use of X-SAR data to retrieve rain precipitation and its validation with radar observations; (4) the improvements of the focusing techniques.
Scientific projects funded by the Italian Space Agency (ASI Agenzia Spaziale Italiana) in the framework of COSMOSkyMed (CSK) program.
National Conference Proceedings
[Nit.GOLD2012] D. O. Nitti, F. Bovenga, "Interferometric DEM generation from COSMO-SkyMED data: potentials and challenges". Proceedings of the 2012 IEEE GOLD Remote Sensing Conference, 4-5 June, 2012. Consiglio Nazionale delle Ricerche, Rome, Italy (available at http://ieee.uniparthenope.it/chapter/gold12.html). ISBN: 978-88-7431-668-7.
The present study is aimed at investigating the potentialities of the COSMO/SkyMed (CSK) constellation of EO satellites equipped with X-band monostatic SAR sensors for ground elevation measurement through InSAR techniques.
Work supported by ASI under contract n. I/063/09/0.
Conference Abstracts
[Nit.EGU2012] D. O. Nitti, R. Nutricato, F. Intini, F. Bovenga, M. T. Chiaradia, R. Pacione, F. Vespe, "On the use of Weather Models in the mitigation of atmospheric artifacts in X-band SAR interferometry". Abstracts proceedings EGU 2012, Vienna, Austria, 22 - 27 April 2012. Abstract ID-No: EGU2012-9872. eISSN: 1607-7962.
High resolution numerical weather models (NWM) are being to play a role of increasing importance for atmospheric phase screen (APS) mitigation. Here we present preliminary investigations concerning the estimation of the atmospheric contribution to X-band InSAR phase fields through numerical weather modeling. We selected tandem-like pairs of Stripmap COSMO/SkyMED images acquired over Parkfield (California, USA) with short normal baselines, thus ensuring low sensitivity to elevation. By using a 30m SRTM DEM available for the area of interest, we generated differential phase fields, mainly related to the difference between atmospheric conditions at the times of the two acquisitions. The interferometric artifacts have been hence compared to independent estimates of the atmospheric phase delay introduced by both wet and dry the components of the troposphere, obtained through Regional Atmospheric Modeling System (RAMS), a finite-difference, primitive equation, three-dimensional mesoscale NWM originally developed at Colorado State University. RAMS is a prognostic model capable of simulating a wide range of atmospheric motions due to the use of a nested grid system. Incorporation of topographic features occurs through the use of a terrain-following vertical coordinate system, while turbulence is parameterized using Mellor and Yamada’s level 2.5 scheme, as modified by Helfand and Labraga for growing turbulence. In order to assess the impact of the boundary conditions, numerical simulations have been repeated by using GFS, ECMWF and NAM data (resolution: 0.5 deg, 0.25 deg and 12km respectively). A spin-up time exceeding 24h was necessary for ensuring a realistic computation of the atmospheric boundary layer depth. Finally, the 3D computation of the scaled-up refractive index and its integration along the Line-Of-Sight (LOS) of the SAR sensor was performed in order to estimate the two-way radar phase delay. The preliminary results confirm the indications coming from recent similar studies: weather models are good for the long wavelengths (>20 km) and for vertical stratification which depends on the hydrostatic component of the troposphere, while they cannot actually ensure a sub-centimetric accuracy in the estimation of the wet component, as instead required in X-band interferometry. Finally, we used the GPS daily RINEX available on the Parkfield area to infer the atmospheric Zenith Total Delay (ZTD) and validate the outcomes of the NWM. GPS data were processed at ASI/CGS by using the NASA/JPL GIPSY-OASIS II for data reduction. The Precise Point Positioning approach was applied fixing JPL fiducial-free satellite orbits, clocks and earth orientation parameters, IGS absolute phase center variations and estimating, with a cut-off angle of 7deg, site coordinates, station clock, phase ambiguities, ZTD and tropospheric gradients. ZTD and tropospheric gradients are modeled as random walk processes and estimated with a sampling rate of 5 minutes. Results show correlation between the values computed by NWM and GPS. Furthermore, the differences are not correlated with the topography thus suggesting that the main cause of the mismatches relies on the tropospheric turbulence. This further confirms our previous conclusions.
Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the AO-COSMO Projects ID-1462 “Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation Contract I/063/09/0” and ID-2103 “Advanced 2D and 3D focusing of COSMO/SkyMed SAR data Contract n. I/059/09/0”. GPS data have been analyzed by e-GEOS under ASI contract I-014-10-0.
[Chi.AGU2012] M. T. Chiaradia, R. Nutricato, D. O. Nitti, F. Bovenga, L. Guerriero, "Railway infrastructure monitoring with COSMO/SkyMed imagery and multi-temporal SAR interferometry". AGU Fall Meeting 2012 Abstract, NH13A-1597, San Francisco, California, USA, 3-7 Dec. 2012. http://abstractsearch.agu.org/meetings/2012/FM/sections/NH/sessions/NH13A/abstracts/NH13A-1597
For all the European Countries, the rail network represents a key critical infrastructure, deserving protection in view of its continuous structure spread over the whole territory, of the high number of European citizens using it for personal and professional reasons, and of the large volume of freight moving through it. Railway system traverses a wide variety of terrains and encounters a range of geo-technical conditions. The interaction of these factors together with climatic, and seismic forcing, may produce ground instabilities that impact on the safety and efficiency of rail operations. In such context, a particular interest is directed to the development of technologies regarding both the prevention of mishaps of infrastructures, due to natural disasters and/or to terrorist attacks, and the fast recovery of their normal working conditions after the occurrence of accidents (disaster managing). Both these issues are of strategic interest for EU Countries, and in particular for Italy, since, more than other countries, it is characterized by a geo-morphological and hydro-geological structure complexity that increases the risk of natural catastrophes due to landslides, overflowings and floods. The present study has been carried out in the framework of a scientific project aimed at producing a diagnostic system, capable to foresee and monitor landslide events along railway networks by integrating in situ data, detected from on board sophisticated innovative measuring systems, with Earth Observation (EO) techniques. Particular importance is attached to the use of advanced SAR interferometry, thanks to their all-weather, day-night capability to detect and measure with sub-centimeter accuracy ground surface displacements that, in such context, can occur before a landslide event or after that movements. Special attention is directed to the use of SAR images acquired by COSMO/SkyMed (ASI) constellation capable to achieve very high spatial resolution and very short revisit and response time. In this context, a stack of 57 CSK stripmap images (pol.: HH; look side: right; pass direction: ascending; beam: H4-03; resolution: 3x3 m2) have been acquired from October 2009 to April 2012, covering the Calabria's Tyrrhenian coast, between the towns of Palmi and Reggio Calabria. The imaged area is of strategic importance since the two towns are connected by a stretch of the Tyrrhenian railway line, a fundamental line (as classified by RFI, the Italian Rail Network) belonging to the TEN-T network, i.e. the trans-european transport network defined since early '90 by the European Commission. Moreover, Calabria region is a challenging area where carrying on an analysis on weathering-related slope movements. In Calabria, on 2009the geo-hydrological crisis was so severe that the Italian Government had to declare the “state of emergency”. This paper concerns the processing of the CSK dataset performed through the SPINUA algorithm a Persistent Scatterers Interferometry technique originally developed with the aim of detection and monitoring of coherent targets in non- or scarcely urbanized areas. The displacement maps derived on the area of interest will be presented and commented with particular attention to the potential impact that such EO-based product can have on the railway networks monitoring.
CSK images provided by ASI (Agenzia Spaziale Italiana) in the framework of the project “Landslide Monitoring and Mapping System - CAR-SLIDE” (PON 01 00536). Optical images provided by GoogleEarth and GoogleStreet. The authors would like to thank dr. J. Wasowski (CNR-IRPI, Bari, Italy) for helpful comments on the achieved results.
[Tij.AGU2012] K. Tijani, M. T. Chiaradia, L. Guerriero, G. Pasquariello, A. Morea, R. Nutricato, G. Preziosa, "Monitoring of urban air pollution from MODIS and AERONET Aerosol Optical Thickness (AOT) data". AGU Fall Meeting 2012 Abstract, A21C-0058, San Francisco, California, USA, 3-7 Dec. 2012.
Air pollution, caused by fuel industries and urban traffic and its environmental impact, are of considerable interest to studies in air quality. In this paper, the monitoring of the air pollution over urban areas in Italy through Aerosol Optical Thickness (AOT) data retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements is presented. The high spatio-temporal frequency of MODIS AOT products (twice per day at 470nm, 1km full resolution) demonstrates that this satellite can be potentially used to routinely monitor the air pollution over land, especially urban area, which is the main source of aerosol particles. In this work AOT data derived by MODIS from November 2010 to February 2011 (winter period) and from May 2011 to August 2011 (summer period) were compared with AOT measurements from 6 different Aerosol Robotic Network (AERONET) stations over Italy (Bari, Lecce, Roma, Ispra, Potenza, Etna). The statistical analysis shows a good agreement between the ground based AOT measurements and the values retrieved using space based sensors, as shown in Figure 1. For all the stations the mean error is negligible, with a correlation ranging from 0.725 (in the worst case) to 0.96 (see Table 1). Moreover, LANDSAT-panchromatic images were used to discriminate urban and rural areas, based on the typical finger-like projections of urban land uses. The results of this study will be presented and commented.
This work was funded by Apulian Region in the framework of the ECOURB project. (Analisi e Modelli di inquinamento atmosferico e termico per sistemi di ECOlabeling URBano, 2009-2012).
[Bel.CeTeM2012] A. Belmonte, A. Refice, F. Bovenga, G. Pasquariello, R. Nutricato, "Interpolation and unwrapping of sparse-grid InSAR data". VII Riunione Annuale CeTeM-AIT sul Telerilevamento a Microonde: sviluppi scientifici ed implicazioni tecnologiche Bari, 4-5 dicembre 2012.
Applications such as SAR interferometry [1] are increasingly used in “sparse” contexts, in which information about some geophysical parameters (e.g. millimetric terrain deformations) are only available over some of the imaged pixels, corresponding to stable objects [2]. In such cases, it is often necessary to adapt processing algorithms, developed and optimized for regular data grids, to work on sparse samples. One of such algorithms, at the basis of several InSAR processing chains, is the so-called phase unwrapping (PU), consisting of obtaining absolute phase values (i.e. defined over the whole real interval) from the corresponding principal values, i.e. limited to the interval. Recently, a method to reduce the unwrapping problem of a sparse-grid field to one corresponding to a regular grid, has been proposed [3], based on a preliminary nearest-neighbor interpolation step. The solution to the sparse problem is shown to be mathematically equivalent to that of a corresponding regular grid problem, properly derived from the former. The approach allows to employ existing algorithms for regular-grid PU, such as those based on network theory (e.g. the so-called Minimum Cost Flow, or MCF). In this work, stemming from an analysis of the above-mentioned methodology, giving as a solution an absolute phase significant only over the sampled pixels, we propose an alternate procedure, in which the principal phase interpolation step is based on algorithms more advanced than the simple nearest-neighbor scheme. Such interpolation can be performed over the unit-magnitude complex field obtained from the wrapped phase. In this way, the obtained wrapped phase field results more similar to the original, “physical” regular field from which the sparse samples have been obtained. In the case in which this latter field can be assumed to satisfy general conditions of smoothness and homogeneity [4], this allows to exploit at best such characteristics, and to have finally an absolute phase regular matrix more representative of the real data, and then more effective to use in the subsequent processing steps [5]. In the paper, several interpolators are considered, such as radial basis functions (RBF), as well as, more generally, Kriging [6], and their performances and application limits are evaluated in simulation, as a function of both the regularity conditions of the original sampled surface, and the sampling density.
[Was.EOSantorini2012] J. Wasowski, F. Bovenga, D. O. Nitti, R. Nutricato, "Investigating landslides and unstable slopes with C- and X-band PSI: current opportunities and challenges". International Forum on Satellite EO for Geohazard Risk Management, 21-23 May 2012. Santorini Convention Centre, Greece.
Persistent Scatterers Interferometry (PSI) and other similar multi-temporal synthetic aperture radar differential interferometry (DInSAR) techniques are capable to provide wide-area coverage (thousands km2) and precise (mm-cm resolution), spatially dense information (from hundreds to over thousand measurement points/km2) on ground surface deformations. Furthermore, new application opportunities are emerging thanks to i) the greater data availability offered by recent launches of radar satellites, and ii) the improved capabilities of the new space radar sensors (X-band Cosmo-SkyMed, RADARSAT-2, TerraSAR-X) in terms of resolution (from 3 to 1 m) and revisit time (from 11 to 4 days for X-band acquisitions). This in turn implies more and better resolution information about ground surface displacements as well as improved landslide monitoring and slope instability investigation capabilities. The applicability of the multi-temporal DInSAR techniques to regional and localscale investigations of slow landslides has already been demonstrated in many studies. However, to foster a more profitable use of these techniques in landslide investigations additional progress needs to be made in our understanding of small ground surface deformations detected from SAR data and in their integration with ground-based information. Examples of PSI applications to landslide monitoring and slope instability detection in different geomorphological and climatic settings are presented to illustrate i) the potential of the technique to provide, under suitable conditions, valuable reconnaissance and site-specific information on slope surface deformations, ii) the challenges in inferring the exact cause(s) of slow displacements (mm-cm/year) commonly registered on radar targets and the risks of misinterpretation; iii) the utility of Google Earth tools for 3D visualization and preliminary analysis of PSI results. Finally, specific recommendations and guidelines are offered on how to mitigate limitations of PSI applied to landslide and slope instability investigations and how to avoid erroneous interpretations of ground deformation measurements obtained from SAR data.
[Nit.TGRS2011] Nitti D.O., Hanssen R.F., Refice A., Bovenga F. and Nutricato R., “Impact of DEM-assisted coregistration on high-resolution SAR interferometry”. IEEE Transactions on Geoscience and Remote Sensing, vol. 49 (3): 1127-1143, March 2011. DOI: 10.1109/TGRS.2010.2074204. ISSN: 0196-2892. WOS:000287658000020. Scopus: 2-s2.0-79952039240. IF: 2.90 (Year: 2011 - Source: ResearchGate - http://is.gd/OYvz3D)
Image alignment is a crucial step in synthetic apertureradar (SAR) interferometry. Interferogram formation requires images to be coregistered with an accuracy of better than a few tenths of a resolution cell to avoid significant loss of phase coherence. In conventional interferometric precise coregistration methods for full-resolution SAR data, a 2-D polynomial of low degree is usually chosen as warp function, and the polynomialbparameters are estimated through least squares fit from the shifts measured on image windows. In case of rough topography or long baselines, the polynomial approximation may become inaccurate, leading to local misregistrations. These effects increase with spatial resolution of the sensor. An improved elevation-assisted image-coregistration procedure can be adopted to provide better prediction of the offset vectors. This approach computes pixel by pixel the correspondence between master and slave acquisitions by using the orbital data and a reference digital elevation model (DEM). This paper aims to assess the performance of this procedure w.r.t. the “standard” one based on polynomial approximation. Analytical relationships and simulations are used to evaluate the improvement of the DEM-assisted procedure w.r.t. the polynomial approximation as well as the impact of the finite vertical accuracy of the DEM on the final coregistration precision for different resolutions and baselines. The two approaches are then evaluated experimentally by processing high-resolution SAR data provided by the COnstellation of small Satellites for the Mediterranean basin Observation (COSMO/SkyMed) and TerraSAR-X missions, acquired over mountainous areas in Italy and Tanzania, respectively. Residual-range pixel offsets and interferometric coherence are used as quality figure.
The authors would like to thank M. Arikan (TU Delft, The Netherlands) for the fruitful discussions on SAR coregistration and the anonymous reviewers for their valuable suggestions. The COSMO/SkyMed data were kindly provided by the Italian Space Agency (ASI) in the framework of theMORFEO project. The TerraSAR-X data (Infoterra) were kindly provided by Infoterra and acquired within the Study and Monitoring of Active African Volcanoes Project, coordinated by the Royal Museum for Central Africa in Belgium and National Museum of Natural History of Luxembourg.
[Rea.GRSL2011] D. Reale, D. O. Nitti, D. Peduto, R. Nutricato, F. Bovenga, G. Fornaro, “Post-seismic Deformation Monitoring With The COSMO/SKYMED Constellation”. IEEE Geoscience and Remote Sensing Letters, vol. 8 (4): 696-700, July 2011. DOI: 10.1109/LGRS.2010.2100364. ISSN: 1545-598X. WOS:000292105300023. Scopus: 2-s2.0-79959691919. IF: 1.56 (Year: 2011 - Source: ResearchGate - http://is.gd/PiwToa)
COSMO/SKYMED is currently the unique constellation of synthetic aperture radar (SAR) sensors operative, which is also for civilian use. On April 6, 2009, an Mw 6.3 earthquake struck the city of l’Aquila in Central Italy. The constellation acquired data stacks over the hit area at an unprecedented temporal rate. In this letter, the results obtained by processing several data set via two independent multitemporal differential interferometric SAR techniques are presented to demonstrate the capability of this constellation in postseismic deformations monitoring.
The authors would like to thank N. D’Agostino (INGV) for the support in the result interpretation and L. Candela (ASI) and B. De Bernardinis (DPC) for the support to the COSMO data access. The work was carried out under the ASI Contract I/045/07/0 "MOnitoraggio del Rischio da Frana mediante dati EO (MORFEO)."
[Mat.IJRS2011] R. Matarrese, M. T. Chiaradia, K. Tijani, A. Morea, R. Carlucci, "'Chlorophyll a' multi-temporal analysis in coastal waters with MODIS data". Italian Journal of Remote Sensing - 2011, 43 (3): 39-48. DOI: 10.5721/ItJRS20114333. Scopus: 2-s2.0-84857762251. WOS:000302401300004. ISSN: 1129-8596. IF: 0.47 (Year: 2011 - Source: https://goo.gl/x5icVo)
The availability of a nearly-continuous remotely-sensed chlorophyll ‘a’ maps (Chl a) from MODIS sensor, now longer than ten years, enables the assessment of multi-temporal trends for several locations around the world. In this paper the statistical method of the Support Vector Machine (SVM) has been applied to 5 years of MODIS data in order to generate Chl a maps. A Chl a multi-temporal analysis of Apulian region coastal zones in Southern Italy shows a positive trend in two test cases, confirming the increase of productivity in Southern Adriatic region found in the last years and demonstrating the simplicity and usefulness of this technique.
The research activity has been carried out in the framework of IMCA project (Integrated Monitor of Coastal Areas). Authors wish to thank the anonymous referees for their kind efforts and helpful comments.
International Conference Proceedings
[Bov.FRINGE2011] F. Bovenga, D. O. Nitti, A. Ganas, K. Chousianitis, "Co-seismic deformation due to the Tohoku-Oki Earthquake measured by Envisat-ASAR data and GPS". Proceedings of the Workshop Fringe 2011 - Advances in the Science and Applications of SAR Interferometry from ESA and 3rd party missions, September 19-23, 2011, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-697. ISBN 978-92-909226-1-2. ISSN 1609-042X.
On March 11th, 2011, 05:46 UTC, a giant earthquake of magnitude Mw=9.0 occurred off the Pacific coast of Tohoku, Honshu Island, Japan. Massive damage has been reported, mainly related to the subsequent tsunami. In this work we present first results concerning the displacement induced by the Tohoku-oki earthquake by using ASAR ENVISAT data acquired few days before and after the event. The work points out the reliability of ASAR ENVISAT data to provide interferometric-based displacement field even though the satellite is recently came into a new operative phase with degraded orbital control and SAR data were processed in an emergency framework soon after the acquisition without precise orbital records. After removing artefacts due to strong orbital errors, the interferometric deformation pattern is mainly related to the coseismic displacement and it results comparable to that provided by the GEONET GPS network which has an unique density of in situ measurements found elsewhere in the world.
Preliminary GPS time series provided by the ARIA team at JPL and Caltech. All original GEONET RINEX data provided to Caltech by the Geospatial Information Authority (GSI) of Japan. ENVISAT data are provided by ESA through the GEO Geohazards Supersite (http://supersites.earthobservations.org).
[Was.FRINGE2011] J. Wasowski, F. Bovenga, D. O. Nitti, R. Nutricato, T. Dijkstra And X. Meng, "PSI helps to map relative susceptibility to ground and slope instabilities in the Lanzhou loess area of Gansu Province, China". Proceedings of the Workshop Fringe 2011 - Advances in the Science and Applications of SAR Interferometry from ESA and 3rd party missions, September 19-23, 2011, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-697. ISBN 978-92-909226-1-2. ISSN 1609-042X.
The PSI (Persistent Scatterer Interferometry) processing of ENVISAT ASAR data (period 2003-2010) provided spatially dense information (more than 400 PS/km2) on ground surface displacements in Lanzhou, capital of Gansu Province, NW China. The geomorphological and geological context of the local Yellow River valley indicate that the lower, flat areas with floodplain and valley-fill deposits (Holocene terraces with mainly reworked loess at the surface) are stable, whereas some higher, gently sloping valley sides appear locally unstable, particularly where the Late Pleistocene terraces are covered by young aeolian (Malan) loess. The PS velocity data suggest that the relative susceptibility to ground and slope instabilities is the highest on the 4th and 5th order river terraces. This is consistent with the presence of collapsible Malan loess and recent land use of these terraces involving irrigation and construction
ENVISAT images were provided by ESA in the framework of CAT-1 project #7444 “Exploitation of ENVISAT radar data for ground and infrastructure instability hazard assessments in the Lanzhou area (Gansu Province, China)", PI - J. Wasowski. We also thank Jianjun, Xiao Li, Runqiang and Yating who helped in the field reconnaissance.
[Bov.FRINGE2011b] F. Bovenga, V. M. Giacovazzo, A. Refice, D.O. Nitti, N. Veneziani, "Interferometric multi-chromatic analysis of high resolution X-band data". Proceedings of the Workshop Fringe 2011 - Advances in the Science and Applications of SAR Interferometry from ESA and 3rd party missions, September 19-23, 2011, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-697. ISBN 978-92-909226-1-2. ISSN 1609-042X.
The Multi-Chromatic Analysis (MCA) consists of performing sub-bands splitting in range frequency domain, thus generating chromatic views of lower range resolution, centered at different carrier frequencies. Multi-chromatic interferograms can be then generated by coupling chromatic views coming from an interferometric pair of SAR images. The interferometric phase of spectrally-stable scatterers evolves linearly with the sub-band central frequency, the slope being proportional to the absolute optical path difference. Unlike the standard “monochromatic” InSAR approach, this new technique allows performing spatially independent and absolute phase unwrapping (PU). Potential applications for the study of spectrally-stable targets include topographic measurements, atmospheric research or urban monitoring. The technique appears optimally suited for new-generation, wide-band, high-resolution satellite SAR sensors. This work presents first successful applications of the technique using both TerraSAR-X (TSX) and COSMO/SkyMed (CSK) spotlight data. In particular, we provide results concerning the use of MCA for performing absolute PU as well as for height measurement on a pixel-by-pixel basis. Moreover, the impact of coregistration procedure on the MCA-based inference is investigated.
Work supported by both ESA ESTEC Contr. N. 21319/07/NL/HE and ASI Contr. I/047/09/0. COSMO/SkyMed data provided by ASI under the AO-COSMO Project ID-1820. TerraSAR-X data over Ayers Rock are made freely available by InfoTerra (http://www.infoterra.de/tsx/freedata/start.php)
National Conference Proceedings
[Amo.POLEMIO2011] G. Amoruso, G. Tedeschi, R. Corbino, F. Intini, "Monitoraggio meteoclimatico finalizzato ad attività di Protezione Civile (previsione, prevenzione e allertamento) nel tempo reale e ad attività di pianificazione nel tempo differito", Atti delle Giornate di Studio "Impatto delle modificazioni climatiche su rischi e risorse naturali. Strategie e criteri d'intervento per l'adattamento e la mitigazione", Bari, Aula Magna del Dipartimento di Geologia, 10-11 Marzo 2011. In: “Le modificazioni climatiche e i rischi naturali”. Polemio M. (Ed.), ISBN 9788890508806, CNR IRPI, Bari, 2011.
La disponibilità di una serie storica di dati termopluviometrici, rilevati dalla rete regionale di misura al suolo, ha permesso di realizzare mappe climatiche regionali, ottenute con tecniche geostatistiche (kriging), relative al trentennio 1976-2005. Al fine di porre in atto misure di mitigazione nelle aree ad elevato rischio idraulico, il Centro Funzionale Regionale ha potenziato la rete di monitoraggio. Nuovi sensori idrometrici sono stati installati sul bacino interregionale del fiume Fortore che, negli ultimi anni, è stato ripetutamente interessato da eventi meteorologici avversi che hanno coinvolto la Protezione Civile regionale nella gestione delle relative situazioni di criticità.
[Bar.SPATIAL2011] E. Barca, G. Passarella, A. Morea, "A software for optimal information based downsizing/upsizing of existing monitoring networks". Proceedings of Workshop "Spatial Data Methods for Environmental and Ecological Processes". (SPATIAL2), Foggia, 1-3 September 2011. Ed. B. Cafarelli. Cdp Service Edizioni, CD ROM.
Using reliable stochastic or deterministic methods, it is possible to rearrange an existing network by eliminating, adding or moving monitoring locations producing the optimal arrangement among any possible. In this paper, some spatial optimization methods have been selected as more effective among those reported in literature and implemented into a software M-Sanos able to carry out a complete redesign of an existing monitoring network. Both stochastic and deterministic methods have been embedded in the software with the option of choosing, case by case, the most suitable with regard to the available information. Finally, an application to the existing regional groundwater level monitoring network of the aquifer of Tavoliere located in Apulia (south Italy) is presented.
[Was.EGU2011] J. Wasowsky, F. Bovenga, D. O. Nitti, R. Nutricato, T. Dijkstra, X. Meng, "Detecting very slow ground movements using PS interferometry in the Lanzhou loess area of Gansu Province, China". Abstracts proceedings EGU 2011, Vienna, Austria, 03 - 08 April 2011. Abstract ID-No: EGU2011-11139. eISSN: 1607-7962.
Ground instability monitoring and control traditionally rely on qualitative, often subjective geomorphological assessments and, where affordable, on relatively expensive in situ investigations. Due to limited opportunities for in situ instrumentation (cost, reliability and robustness) there is often a serious lack of monitoring data. Thenuse of PSI (Persistent Scatterer Interferometry) results, provides a welcome opportunity to test and calibrate bexisting slope deformation models against independent monitoring data. The advantages and limitations of PSI for ground instability detection and monitoring are evaluated for the semi-arid loess area of the city of Lanzhou (Gansu Province, China) home to over 3 million people. In this tectonically active region, ground instability in the loess and underlying bedrock is widespread and Lanzhou pays an increasingly high price due to lost lives and livelihoods as the city and its environs continue to develop in an unstable terrain. More than 40 ENVISAT ASAR datasets (period 2003-2010) were pre-processed to obtain stacks of co-registered differential SAR interferograms. Then the SPINUA algorithm was used to perform multi-temporal analysis on the co-registered DInSAR stacks in order to correct for spurious effects such as atmospheric artefacts and DEM error, and obtain precise displacement information over selected radar targets (PS). The analysis resulted in the identification of over 140,000 PS in the greater Lanzhou area (about 300 km2). The PSI displacement map of Lanzhou reveals several zones characterized by the presence of moving PS (with average velocities typically from a few mm/yr to several mm/yr). The optical image interpretation and first reconnaissance field checks indicate that we detected only a limited number of moving radar targets potentially indicative of unstable slopes. Instead, the majority of the detected moving persistent scatterers appear to be associated with local subsidence and settlement/structure instability processes. It may often be difficult to ascertain the exact origin of low strain rates, especially when these are detected on steep slopes, because these can arise from different causes (e.g. subsidence and local settlements, shallow seasonal creep, true slope/landslide movements, volumetric changes of geological/artificial materials, tectonics, and instability of structures that act as radar targets). Thus, ground truthing in the form of correlating displacements with information on local geology, geomorphology and slope history, as well as detailed in situ inspections is essential for the correct interpretation of any PSI displacement map.
ENVISAT images were provided by ESA in the framework of CAT-1 project #7444 "Exploitation of ENVISAT radar data for ground and infrastructure instability hazard assessments in the Lanzhou area (Gansu Province, China)".
[Chi.AGU2011] M. T. Chiaradia, D. O. Nitti, F. Bovenga, F. Intini, R. Nutricato, K. Tijani, "On the COSMO-SkyMed Exploitation for Interferometric DEM Generation". AGU Fall Meeting Abstract, EP41A-0574, San Francisco, California, USA, 5-9 Dec. 2011. http://abstractsearch.agu.org/meetings/2011/FM/sections/EP/sessions/EP41A/abstracts/EP41A-0574
DEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). We present results obtained by processing both SPOTLIGHT and STRIPMAP acquisitions through standard SAR Interferometry as well as multi-pass interferometry [4] with the aim of measuring ground elevation.
Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the project “AO-COSMO Project ID-1462 - Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation - ASI Contract I/063/09/0”.
[Nut.GEOITALIA2011] R. Nutricato, D. O. Nitti, F. Bovenga, M. T. Chiaradia, "On the COSMO-SkyMed Exploitation for Interferometric DEM Generation". Epitome of GeoItalia 2011, VIII Forum Italiano di Scienze della Terra, Turin, Italy, 19-23 Sept. 2011. ISSN 1972-1552.
DEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). Both SPOTLIGHT and STRIPMAP acquisition modes are analyzed through standard SAR Interferometry as well as multi-pass interferometry [4]
Work supported by ASI (Agenzia Spaziale Italiana) in the framework of the project "AO-COSMO Project ID-1462 - Feasibility of possible use of COSMO/SkyMed in bistatic SAR Earth observation - ASI Contract I/063/09/0".
[For.WLF2011] G. Fornaro, D. O. Nitti, R. Nutricato, F. Bovenga, D. Peduto, L. Cascini, "Technological and Methodological Advances in the Application of Spaceborne DInSAR for Landslide Monitoring". Abstract n. WLF2 - 2011- 0516 in: "Catani F., Margottini C., Trigila A., Iadanza C. (eds) 2011. The Second World Landslide Forum - Abstract Book, 3-9 October 2011, FAO, Rome, Italy, ISPRA. ISBN 978-88-448-0515-9".
Multipass Differential Interferometry Synthetic Aperture Radar (DInSAR) is today a well established technique for ground deformation monitoring in many areas of natural risk analysis. Compared to classical geodetic techniques such as leveling and GPS it provides advantages in terms of costs, coverage, data accessibility and availability of data archives. Application to different areas of the risk management such as monitoring of volcanoes, tectonic movements, urban areas and infrastructure and slope instabilities, has been already successfully demonstrated. As far as the landslide monitoring is concerned, the monitoring of surface deformation via the DInSAR technique may provide useful information regarding the spatial and temporal distribution of slow moving landslides and their kinematics characteristics. However, among all the DInSAR applications, landslides monitoring is particularly critical due to the presence of vegetation and to the occurrence of the phenomena in areas typically characterized by slope variations. Accordingly, the interpretation of the measurements can be affected by variations of the direction of the surface movement as well as of geometric distortions induced by the topography variations. Classical applications of the DInSAR techniques has been carried out in the past on medium resolution data acquired by the ERS, Envisat and Radarsat sensors. The new generation of high-resolution X-Band SAR sensors, such as TerraSAR-X and the COSMO-SkyMed constellation allows acquiring data with spatial resolution reaching metric/submetric values. Thanks to the finer spatial resolution with respect to data, X-band InSAR applications appear very promising for monitoring single man-made structures, also isolated, thus giving more chances to provide displacement records for landslide investigation in particular where data show low density of coherent scatterers. This work aims to describe the advances in terms of methodological development for the interpretation of DInSAR measurements for landslide monitoring and to provide a “view” on the improvements associated with the new generation high resolution SAR sensors. In particular a DInSAR data interpretation approach based on the joint use of remote sensed data and simplified geomorphological models is discussed. This procedure, tested via the application of a Small BAseline Subset (SBAS) (two-scale analysis) approach to data acquired by the medium resolution satellites, allows the estimation of the vector ground displacement, thus improving the result interpretation. Furthermore, the recent results of the application of a Persistent Scatterers Interferometry technique, namely the SPINUA (Stable Point INterferometry over Unurbanized Areas) algorithm, to data acquired by the COSMO-SKYMED satellite constellation in areas of the Italian territory are presented
[Nut.WLF2011] R. Nutricato, J. Wasowski, F. Bovenga, A. Refice, G. Pasquariello, D. O. Nitti, M. T. Chiaradia, "C/X-band interferometry applied to slope instability monitoring in the Daunia mountains, Italy". Abstract n. WLF2 - 2011- 0552 in: "Catani F., Margottini C., Trigila A., Iadanza C. (eds) 2011. The Second World Landslide Forum - Abstract Book, 3-9 October 2011, FAO, Rome, Italy, ISPRA. ISBN 978-88-448-0515-9".
Thanks to the all-weather, day-night capability to detect and quantify accurately small ground surface deformations, Synthetic Aperture Radar (SAR) Interferometry (InSAR) techniques are attractive for landslide hazard investigations. In particular, multi-temporal InSAR techniques allow to detect and monitor millimetric displacements occurring on selected point targets exhibiting coherent radar backscattering properties (mainly buildings and other man-made structures). In the present work we apply the SPINUA (Stable Point INterferometry over Un-urbanised Areas) multi-temporal processing technique [1] to the Daunia region located in Southern Apennines, Italy. This region includes several small hill-top towns affected by slope instability problems and is of particular interest for the Civil Protection – Regione Puglia Authority, which is one of the end users of the deformation maps derived by multi-temporal interferometric analysis of satellite data. This site was already investigated in the past though interferometric analysis [2] by using ERS-1/2 SAR data provided by ESA. In this work we present results obtained by processing SAR data acquired by the ENVISAT ESA satellite (, medium spatial resolution) as well as by the TerraSAR-X satellite (X-band high resolution) launched by DLR in 2007. Thanks to the finer spatial resolution with respect to data, X-band InSAR applications appear very promising for monitoring single man-made structures (buildings, bridges, railways and highways) as well as areas where data show low PS density. This is the case, in particular, of the Daunia region which is scarcely urbanised. Indeed, the results obtained with X-band data suggest that many more man-made and natural targets behave as persistent scatterers than in . Moreover, thanks again to the higher resolution, it should be possible to infer reliable estimates of the displacement rates with a number of SAR scenes significantly lower than in within the same time span or by using more images acquired in a narrower time span. Finally, with shorter wavelengths the sensitivity to LOS displacements is increased together with the capability of detecting very low displacements rates (as the pre- and post-failure movements related to landslides are expected to be). The displacements maps obtained by processing both C- and X-band SAR data will be presented for a selected number of towns affected by slope instability. Results will be commented with particular attention paid to the advantages provided by the new generation of X-band high resolution space-borne SAR sensors.
[Int.RMSC2011] Franco Intini, G. Amoruso, M. T. Chiaradia, R. Corbino, Francesca Intini, G. Tedeschi, K. Tijani, “High Resolution Rams Implementation On Apulia Region And Forecast Fields Validation By Comparison With Ground Observations”. Royal Meteorological Society Conference 2011, University Of Exeter, Uk, 27-30 June 2011.
A forecasting system has been implemented for operational forest fire hazard prediction over Apulia region (Italy) in the framework of an agreement between Geophysical Applications Processing (Polytechnic of Bari) and Apulia Region Civil Protection. The modelling chain, composed of a limited area model for weather forecasting and a model based on Fire Weather Index, has been executed during the whole summer season June-September 2009 and validated by comparison with available meteorological observations and fire occurrence data. In this paper the validation results of weather forecasting module are presented. Atmospheric fields prediction has been performed by the Regional Atmospheric Modeling System (RAMS), in a two nested grids configuration with the inner grid resolution at 4km. The atmospheric boundary and initial conditions were obtained from GFS data available every 6h with 0.5° resolution. Vertical discretization consisted of a 30-level stretched vertical coordinate with a 50m spacing near the surface increasing gradually up to 1200m near the model top at 19000m. The Kuo convective parameterization scheme has been activated on both grids and the full package for microphysics has been used with a single-moment bulk scheme. In the present work the validation of precipitation and temperature forecast fields is discussed. The validation criteria were based on the comparison with rain gauges and thermometer observations: in both cases measurements from regional Civil Protection thermo-pluviometric monitoring network have been employed. The tests conducted show a generally satisfactory RAMS model performance and forecast values in a good agreement with ground measurements. Currently, there is a sperimentation (in the context of recent research projects funded by Italian Space Agency) of further applications of the model with reference to atmospheric correction estimation in the development of advanced processing techniques for focusing of COSMO-SkyMed data and interferometric DEM generation.
[Nit.PhDXXII] D.O. Nitti, "Geohazards Monitoring through Multitemporal L&X-band SAR Interferometry". PhD Thesis (XXII ciclo), Scuola Interpolitecnica di Dottorato (Sede di assegnazione: Politecnico di Bari. Area scientifica: Sicurezza e Controllo di Ambiente e Territorio). Corso di dottorato in Ingegneria e Chimica per la tutela degli ecosistemi. Supervisori: Prof. Umberto Fratino (POLIBA) e Prof. Luciano Guerriero (POLIBA). Coordinatore: Prof. Antonio Felice Petrillo (POLIBA). SSD: FIS/01, GEO/05
The present study was aimed at experimenting the use of multi-temporal SAR interferometry techniques in order to provide a first assessment of the performances of the innovative L- & X-band SAR missions recently launched into orbit. The processing refinements for a proper interferogram generation, required especially by X-band data, because of their spatial resolution one order of magnitude better than the previous available satellite SAR data, have been widely discussed, particularly for image alignment, one of the most crucial steps in SAR interferometry. The better performances of an innovative DEM-assisted procedure w.r.t. conventional ones, based on polynomial approximation of the warp functions, have been discussed and assessed through simulations for the three radar bands, as well as real processing examples. The Stable Point INterferometry over Un-urbanized Areas (SPINUA) algorithm, a joint effort of Politecnico di Bari and the CNR-ISSIA institute of Bari, Italy, has been applied and tested over a number of test sites affected by disparate hydrogeological instability conditions. SPINUA is a PSI processing methodology which has originally been developed with the specific aim of detection and monitoring of coherent PS targets in non or scarcely urbanized areas. The actual availability of wide-bandwidth, high-frequency, high-resolution X-band SAR data discloses completely innovative investigation realms, contributing to improved monitoring capabilities of spaceborne remote sensing instruments. COSMO-SkyMED constellation, for the civilian side, is dedicated to provide products for environmental monitoring and surveillance. Actually, with two satellites in equi-phased configuration, and a third one in tandem-like mode, CSK constellation is capable to provide SAR data with unprecedented temporal frequency thus resulting extremely advantageous in supporting the emergency phase and geohazard monitoring, such as during and after the emergency related to the Mw=6.3 earthquake which struck the Abruzzo region in Italy on April 6th, 2009. Thanks to the availability of tens of post-seismic CSK acquisitions collected in few months after the mainshock, the post-seismic investigation through PSI techniques has finally proved to be feasible. Post-seismic movements detected by the SPINUA processing chain in just five months are quite impressive around the outcrop of the Paganica fault, i.e. the causative fault of the April 6, 2009 earthquake, but plausible and likely explained in terms of post-seismic rebound. The validation of InSAR-derived displacements has just started in the framework of MORFEO project, a 3-year pilot research and development project founded by ASI, aimed at the development and demonstration of a set of tools that exploit and integrate EO data and technology potentially useful to support the Italian Department of Civil Protection activities at multiple geographical scales. First results show a very good agreement of the InSAR displacements inferred by SPINUA with the leveling data obtained by CNR-IRPI, Torino, through a tacheometric survey in the area of Tempera, close to the Paganica fault. The Venice city area was an optimal test site to assess the performances of the SPINUA PSI processing chain and of some ad hoc solutions, in primis the patch-wise analysis, adopted within the procedure to deal with increased computational costs of X-band interferometry. The results of the SPINUA analysis of a consistent stack of TerraSAR-X data indicate that, in X-band, a number of images equal to about half of those required for C-band sensors could be used to obtain still acceptable results, i.e. equivalent displacement rate estimation capabilities with negligible false alarm rates. The PSI preliminary monitoring of ground instabilities has been extended therefore to case studies where actually a reduced number of X-band acquisitions is available, as it is for some Alpine areas, located in northern Italy, widely affected by landslide phenomena. The results are encouraging as proved by the successful cross-comparison with displacement maps retrieved from independent SAR datasets, acquired by different sensors in the framework of the IFFI project. The exploitation of L-band data, for the monitoring of the mining-induced land sinking affecting the Wieliczka town in Poland, was aimed at covering especially rural or vegetated areas, thanks to a coe±cient of penetration into vegetation much higher than in C-band. However, even including all FBS/FBD acquisitions, the longer orbital cycle and the JAXA acquisition policy did not allow to build a consistent number of PALSAR images so far. Nevertheless, the preliminary L-band PSI analysis confirms that the subsidence is still active with an extension comparable to the one retrieved by processing an ERS dataset, covering the period from 1992 to 2000.
"This study was performed at the Departments of Physics and of Water Engineering and Chemistry of Politecnico di Bari, Italy. I would like first of all to thank prof. Umberto Fratino and especially prof. Luciano Guerriero and Dr. Fabio Bovenga, for their constant support in my research activity. I also acknowledge Fabio for proofreading this thesis. I'm really thankful to Ramon Hanssen, professor in Earth Observation, my supervisor during the permanence abroad at Delft University of Technology (The Netherlands), where I had the opportunity to live for nine months an exciting experience in one of the most active and proficient research group in SAR interferometry. I would mention my colleagues Raffaele Nutricato, from Geophysical Applications Processing s.r.l., a POLIBA spin-off company, and Alberto Refice, from CNR-ISSIA, Bari, for their fruitful collaboration. Finally, but most of all, I would like to thank my wife: I had to neglect her many times in the past years.
SAR data were provided in the framework of the MORFEO project (ASI Contract n. I/045/07/0) and the ASI-INNOVA contract n. I/038/07/0 and I AA. Planimetry and heights over Railway Yard ""S. Lorenzo"" in Rome were provided by ""RFI spa - Dir. Comp. Infr. Roma"". High precision laser scanning Digital Height Model over Langnau im Emmenthal (Switzerland) were provided by ""Amt fÄur Geoinformation, Bau-, Verkehrs und Energiedirektion des Kantons Bern""."
International Conference Proceedings
[Bov.SPIE2010] F. Bovenga, D. O. Nitti, A. Refice, R. Nutricato, M. T. Chiaradia, “Multi-temporal DInSAR analysis with X-band high resolution SAR data: examples and potential”. In Proceedings of SPIE Remote Sensing, 20-23 September 2010, Toulouse, France. DOI: 10.1117/12.866459. ISBN: 9780819483461. ISSN 0277-786X. Scopus: 2-s2.0-78649743122. WOS:000287758300013
The recent availability of wide-bandwidth, high-frequency, high-resolution SAR data is contributing to improved monitoring capabilities of spaceborne remote sensing instruments. In particular, the new COSMO/SkyMed (CSK) and TerraSAR- X (TSX) X-band sensors allow better performances in multitemporal DInSAR and PSI applications than legacy sensors such as ENVISAT ASAR, with respect to both target detection and terrain displacement monitoring capabilities. In this paper we investigate about the possibility of achieving performances of PSI displacement detectioncomparable to those of sensors, by use of reduced numbers of high-resolution X-band . To this end, we develop a simple model for phase and displacement rate measurement accuracies taking into account both target characteristics and sensors acquisition schedule. The model predicts that the generally better resolution and repeat-time characteristics of new-generation X-band sensors allow reaching accuracies comparable to data with a significantly smaller number of X-band acquisitions, provided that the total time span of the acquisitions is large enough. This allows in principle to contain the costs of monitoring campaigns, by using less scenes. Indications are more variable in the case of short-time acquisition schedules, such as those involved in the generation of so-called “rush products” for emergency applications. In this case, the higher uncertainty given by shorter total time spans lowers X-band performances to levels mostly comparable to those of the legacy medium-resolution sensors, so that no significant gain in image number budget are foreseen. These theoretical results are confirmed by comparison of three PSI datasets, acquired by ENVISAT ASAR, CSK and TSX sensors over Assisi (central Italy) and Venice.
The authors are grateful to Claudia Notarnicola (EURAC-Institute of Applied Remote Sensing, Bolzano, Italy) for the fruitful collaboration. ENVISAT and COSMO-SkyMED images are provided respectively by ESA and ASI in the framework of the MORFEO project (ASI Contract n. I/045/07/0). TerraSAR-X data ((c) Infoterra) are provided by Info-terra within the TerraSAR-X General AO Project MTH0432 (PI Maria Teresa Chiaradia).
[Bov.IGARSS2010] F. Bovenga, L. Candela, F. Casu, G. Fornaro, F. Guzzetti, R. Lanari, D. O. Nitti, R. Nutricato and D. Reale, “The COSMO-SkyMED constellation turn on the l’Aquila earthquake: DInSAR results of the MORFEO project.”. In Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 25-30, 2010. Honolulu, Hawaii, USA. DOI: 10.1109/IGARSS.2010.5654016. ISSN: 2153-6996. E-ISBN: 978-1-4244-9564-1. Print ISBN: 978-1-4244-9565-8. ISSN: 2153-6996. eISSN: 2153-7003. Scopus: 2-s2.0-78650879901. WOS: 000287933804246
On April 6th 2009 a Mw=6.3 earthquake struck the area around the city of L’Aquila in Italy. SAR systems have been proven to be valuable sensors for analyzing the effect of earthquakes and monitoring post-seismic displacements. Due to the low deformation rate, the study of post-seismic events requires the use of a multi-temporal InSAR approach. COSMO/SKYMED is a constellation of SAR sensors of 4 X-band sensors operative also for the civilian use. Thanks to the availability of a stack of ascending acquisitions, ad hoc programmed by ASI on the area stricken by the earthquake, it was possible to provide postseismic deformation maps by using two different multitemporal interferometric approaches: the SPINUA and SBAS techniques. The work is carried out in the framework of the MORFEO project dedicated to the monitoring of the landslides risk by means of Earth Observation data. The displacement maps related to the post-seismic activity are presented and commented. The results clearly show the potentiality of the COSMO/SKYMED constellation use for emergency monitoring.
The authors are grateful to the Italian Civil Protection Department, and particularly to Prof. De Bernardinis for the support. This work was supported by ASI, under Contract No. I/045/07/0 “MOnitoraggio del Rishio da Frana mediante dati EO (MORFEO)”.
[Bov.LIVINGPLANET2010] F. Bovenga, D. O. Nitti, R. Nutricato and M. T. Chiaradia, “C- and X-band multi-pass InSAR analysis over Alpine and Apennine regions”. In Proceedings of the European Space Agency Living Planet Symposium, June 28 - July 2, 2010, Bergen, Norway. Vol. ESA SP-686. ISBN 978-92-9221-250-6. ISSN 1609-042X.
In the present work we present results of ground defor-mation measurements inferred through repeat-pass Syn-thetic Aperture Radar (SAR) Interferometry (InSAR) in C- and X-band over Alpine and Apennine sites affected by slope instability. The activity was carried out in the framework of the MORFEO (MOnitoraggio e Rischio da Frana mediante dati EO) project, founded by the Italian Spatial Agency (ASI) and dedicated to landslide risk assessment. A number of areas affected by hydro-geological instabilities have been selected and studied in detail by processing both C- and X-band SAR data through multi-temporal Differential SAR Interferome-try algorithms. InSAR-derived displacements provided on areas of hy-drogeological interest are going to be validated in the framework of MORFEO project by the geological part-nership thanks to the availability of ground truths. In the present work, we present the results obtained by proc-essing through SPINUA, a PS-like algorithm, three ar-eas affected by landslide phenomena: the area around Garzeno and Catasco in the Lombard Alps, the area aver St. Moritz in the Swiss Alps and the Ivancich landslide close to Assisi town in the Italian Apennine. We provide comparison between the deformation maps derived from ENVISAT and those obtained by process-ing a limited number of COSMO-SkyMED images. Our results are also validated by using ERS and RADAR-SAT PS maps freely available on the GeoIFFI web-catalogue (Garzeno), geotechnical investigation avail-able in literature (St. Moritz) and results from SBAS technique (Assisi).
ENVISAT and COSMO-SkyMED images were pro-vided respectively by ESA and ASI in the framework of the MORFEO project (ASI Contract n. I/045/07/0).
National Conference Proceedings
[Nut.ASITA2010] R. Nutricato, D. O. Nitti, M. T. Chiaradia, F. Bovenga, A. Refice, G. Pasquariello, “Rilevamento di deformazioni del suolo in Daunia (Puglia) per mezzo di tecniche interferometriche SAR”. Atti 14a Conferenza Nazionale ASITA, 9–12 Novembre 2010, Fiera di Brescia, Italia. ISBN: 9788890313257.
In this paper we present the research activity carried out in the framework of a project funded by Puglia Region and aimed at using SAR Interferometry for measuring deformations induced by landslides in the Daunia region (Puglia). The area is of particular interest for the Civil Protection – Regione Puglia Authority which is one of the potential end users of the deformation map derived by multi-temporal interferometric analysis of satellite data. The results have been obtained through the SPINUA processing chain (Bovenga et al., 2004) which performs a multi-temporal InSAR Persistent Scatterer-like analysis. These approaches are able to inspect periodically a wide area on the ground measuring sub-vertical displacements with a precision of few millimetres per year for the mean velocity. The algorithm is also able to process the new generation of X-band high resolution SAR data. In the paper we present first results obtained by processing SAR data acquired between 2002 and 2010 by the ENVISAT ESA satellite which works at and medium spatial resolution.
Le immagini sono state fornite dall’ESA nell’ambito del progetto CAT-1 id. 2653, “Advanced SAR Interferometry techniques for landslide warning management”.
[Bel.ASITA2010] V. Bellifemine, F. Bovenga, L. Candela, R. Nutricato, G. Pasquariello, A. Refice, "Identificazione di aree inondate da immagini SAR a media ed alta risoluzione", Atti 14a Conferenza Nazionale ASITA, 9-12 Novembre 2010, Fiera di Brescia, Italia. ISBN: 9788890313257.
Obiettivo del lavoro è stato l’assessment di tecniche automatiche per l’estrazione di aree inondate da immagini SAR. Al fine di raggiungere tale obiettivo sono stati considerati i dati in banda X ad alta risoluzione spaziale (da 1 a 4 m.) della costellazione italiana COSMO-SkyMed. I casi di studio considerati sono stati: l’ esondazione del Dicembre 2009 del Lago di Massaciuccoli, in Toscana e gli eventi di piena relativi al Fiume Tanaro in Piemonte avvenuti negli ultimi giorni dell’Aprile 2009. L’approccio di change detection adottato si basa su una tecnica per la ricerca automatica della soglia sulle immagini delle intensità. Inoltre, lì dove erano disponibili coppie interferometriche con sufficiente correlazione, è stato verificato un approccio basato sulla segmentazione dell’immagine della correlazione interferometrica. Nel lavoro sono presentati i risultati e la valutazione sull’uso in situazioni di emergenza dove viene richiesta l’identificazione più precisa delle aree colpite per la valutazione dei danni e per programmare azioni di pronto intervento.
Gli Autori ringraziano il Prof. Luciano Guerriero del Politecnico di Bari per gli utili suggerimenti ed il Dipartimento della Protezione Civile per il supporto fornito e la disponibilità dimostrata.
[Int.BOSCHI2010] F. Intini, K. Tijani, F. Intini, M. Zippitelli, L. Guerriero, G. Scarascia Mugnozza, "Tecniche modellistiche e satellitari per la previsione ed il monitoraggio del pericolo incendi in Puglia". Atti del Convegno "Previsione, prevenzione e lotta attiva agli incendi boschivi nella Regione Puglia", Facoltà di Agraria, Bari, Febbraio 2010.
I sistemi per il monitoraggio e per la valutazione della pericolosità incendi sono di grande utilità per la lotta attiva agli incendi boschivi. Durante la campagna AIB 2009, il Servizio di Protezione Civile della Regione Puglia ha utilizzato, per la prima volta, in modalità sperimentale, un sistema di previsione della pericolosità incendi composto da un modello meteorologico prognostico non idrostatico RAMS (Regional Atmospheric Modelling System) e da un sistema di calcolo dell’indice canadese di pericolo di incendio FWI (Fire Weather Index). Il sistema modellistico, realizzato da Geophysical Applications Processing (GAP) srl, Spin Off del Politecnico di Bari, è stato implementato in modalità operativa dopo una verifica preliminare effettuata attraverso il confronto con i dati di osservazione raccolti durante la campagna AIB 2008. Il confronto effettuato con i dati registrati dal CFS (Corpo Forestale dello Stato) indica una corrispondenza pari al 77% tra gli incendi di maggiore estensione (> 20ha) avvenuti in aree boscate ed i valori di FWI appartenenti alle due classi più elevate. Uno dei principali vantaggi del sistema modellistico realizzato consiste nella produzione di mappe di previsione di FWI ad una risoluzione nettamente superiore a quella disponibile con altri sistemi analoghi e di mappe di previsione di parametri atmosferici utili alla lotta attiva agli incendi boschivi. La disponibilità in tempo reale di mappe satellitari MSG (Meteosat Second Generation) ha permesso, inoltre, di progettare e realizzare un sistema prototipale per la rilevazione dei fuochi attivi sul territorio pugliese.
Lavoro realizzato nell'ambito della Convenzione tra la Regione Puglia - Servizio Protezione Civile e Geophysical Applications Processing (GAP) srl, Spin Off del Politecnico di Bari (Delibera della Giunta Regionale del 26 novembre 2008, n. 2294).
Conference Abstracts
[Guz.EGU2010] MORFEO Team, "Results of the MORFEO project: Exploiting remote sensing technology to detect, map, monitor, and forecast slope failures". European Geosciences Union General Assembly 2010, Vienna, Austria, 02–07 May 2010. Session NH3.4 Abstract ID-No: EGU2010-11871. eISSN: 1607-7962.
Advances in space borne, airborne and terrestrial remote sensing technologies have improved our ability to identify, map, monitor, and forecast ground deformations, including landslides. In 2001, the Italian Space Agency (ASI) launched a multifaceted call for technological and scientific applications of remote sensing technology to help identify, monitor, forecast, and mitigate natural and manmade hazards, including slope failures. Following this call, in 2007, ASI lunched the MORFEO project, a coordinated research and development initiative aimed at the development and preliminary implementation of a prototype system to support the Italian National Civil Protection Department activities on landslide risk assessment and mitigation, at different spatial and temporal scales. MORFEO, an Italian acronym for Monitoring Landslide Risk through Earth Observation technology, is aimed at the synergic exploitation of Earth observation (EO) data and technologies, consolidated and innovative ground based monitoring tools, and existing and new thematic and environmental information, to improve the ability of the Italian National Civil Protection Department to promptly detect, map, monitor, and forecast landslides of different types, and in different physiographic environments. The MORFEO team is headed by Carlo Gavazzi Space (CGS), a leading European company in space technology, and by IRPI, a research institute of the Italian National Research Council leader in landslide investigations. CGS and IRPI are assisted by a unique multi-disciplinary teamcomprising research institutes, university departments and Italian enterprises collectively experts in landslide identification and mapping, slope monitoring, landslide and environmental hazard and risk assessment and mitigation, and in the innovative exploitation of EO data and technologies. MORFEO is characterized by a significant research component. Due to the difficulty inherent in the use of multiple satellite, airborne, and ground based EO technologies and information for landslide risk assessment and mitigation, executing innovative research is fundamental to the project. In this work, we report on the main research results obtained during the first two years of the project MORFEO.
This work was supported by ASI, under Contract No. I/045/07/0 “MOnitoraggio del Rishio da Frana mediante dati EO (MORFEO)”.
[Was.EGU2010] J. Wasowski, C. Lamanna, D. Casarano, F. Bovenga, D.O. Nitti, R. Nutricato, F. Rana, G. Colangelo, “Interpreting very slow surface movements on slopes detected by PS interferometry and GPS surveying: case study from the Southern Apennines, Italy”, Abstracts proceedings EGU 2010, Vienna, Austria, 02 – 07 May 2010. Abstract ID-No: EGU2010-15380-1. eISSN: 1607-7962.
Advanced multi-temporal DInSAR techniques (eg Persistent Scatterer Interferometry - PSI) can typically detect only very slow ground surface displacements (usually up to few cm/year). We argue that it may often be difficult to ascertain the exact origin of such movements, especially when they occur on hill slopes, because they can arise from different causes (eg subsidence and local settlements, shallow seasonal creep, true slope/landslide movements, volumetric changes of geological/artificial materials, tectonics, instability of structures that act as radar targets). We also draw attention to the practical limitations of PSI in the rural areas, where the density of potential radar targets is low. These difficulties are exemplified here with a case study from the Apennine mountains of southern Italy. Although this area, which includes Potenza, capital city of the Basilicata Region, has been known for its susceptibility to landsliding, PSI analysis based on over 30 ENVISAT ASAR ascending and descending acquisitions (covering 2003 to 2009) detected only a limited number of moving radar targets potentially indicative of instable slopes. Instead, the majority of the detected moving persistent scatterers can be associated with local subsidence and settlement/structure instability processes (with average velocities up to several and a few mm/yr, resp.). Nevertheless, one case of a large landslide re-activated in a rural area in 2006 shows that GPS surveying and PSI application, respectively, monitoring the points on the landslide and on nearby buildings, can furnish complementary information useful for the assessment of relative hazard. Thus, local knowledge (geology, geomorphology, slope history) and in situ inspections could often be essential for the correct interpretation of PSI displacement maps. Furthermore, note that the exploitation of both descending and ascending imagery — two independent analyses — not only offers the simplest form of reciprocal validation but also helps overcome interpretative difficulties linked to the 1-D nature of PSI displacement results.
[Smi.JGR2009] A. Smirnov, B. N. Holben, I. Slutsker, D. M. Giles, C. R. Mcclain, T. F. Eck, S. M. Sakerin, A. Macke, P. Croot, G. Zibordi, P. K. Quinn, J. Sciare, S. Kinne, M. Harvey, T. J. Smyth, S. Piketh, T. Zielinski, A. Proshutinsky, J. I. Goes,N. B. Nelson, P. Larouche, V. F. Radionov, P. Goloub, K. Krishna Moorthy, R. Matarrese, (2009) "Maritime Aerosol Network as a component of Aerosol Robotic Network". Journal Of Geophysical Research, VOL. 114, D06204, DOI:10.1029/2008JD011257, 2009. ISSN (printed): 0148-0227. ISSN (electronic): 2156-2202.
The paper presents the current status of the Maritime Aerosol Network (MAN), which has been developed as a component of the Aerosol Robotic Network (AERONET). MAN deploys Microtops handheld Sun photometers and utilizes the calibration procedure and data processing (Version 2) traceable to AERONET. A web site dedicated to the MAN activity is described. A brief historical perspective is given to aerosol optical depth (AOD) measurements over the oceans. A short summary of the existing data, collected on board ships of opportunity during the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project is presented. Globally averaged oceanic aerosol optical depth (derived from island-based AERONET measurements) at 500 nm is ~0.11 and Angstrom parameter (computed within spectral range 440–870 nm) is calculated to be ~0.6. First results from the cruises contributing to the Maritime Aerosol Network are shown. MAN ship-based aerosol optical depth compares well to simultaneous island and near-coastal AERONET site AOD.
The authors thank Hal Maring (NASA Headquarters) for his support of AERONET. The authors would like to acknowledge managerial and operational support from W.W. Newcomb, M. Sorokin, A. Scully, A. Tran, D.A. Siegel, K. Knobelspiesse, D. Hamilton, L. Rainville, A. Jayakumar, S. Schick, and D. Menzies (USA); N.T. O’Neill, C. Bourgeault-Brunelle, and M. Palmer (Canada); M. Panchenko, O. Kopelevich, S. Gulev, D. Kabanov, S. Terpugova, V. Polkin, A. Tikhomirov, A. Sinitsyn, Y. Turchinovich, and N. Vlasov (Russia); L. Blarel, J. Nicolas, S. Devidal, L. Martinon, M. Faillot, and C. Petus (France); A. Baker and C. Powell (UK); A. Herber, Y. Zoll, A. Wassmann, and M. Heller (Germany); H. Power, T. Bromley, and R. Martin (New Zealand); J. Piskozub, J. Kowalczyk, and A. Ponczkowska (Poland); D. Williams and B. Kuyper (South Africa); J. Stamnes and S. Iversen (Norway); and K. Niranjan, S. Babu, and S.K. Satheesh (India). We thank the AERONET site managers and the SIMBIOS principal investigators for maintaining the instruments and making collection of these data possible. Jean Sciare would like to thank Institut Polaire Francais (IPEV) and the IPEV-AEROTRACE observatory program for providing technical support and infrastructure. The work of Tymon Zielinski was supported by Polish national grant AERONET59.
[Was.PGR2009] J. Wasowski, F. Bovenga, R. Nutricato, D. Conte, A. Refice, M. Graniczny, Z. Kowalski. "Spatial distribution of subsidence in the Wieliczka Salt Mine area as detected through satellite interferometry". In Przeglad Geologiczny, vol. 57, nr 2, 2009, pages 164-172. ISSN-0033-2151.
The paper presents the use of the Persistent Scatterers Interferometry (PSI) Synthetic Aperture Radar (SAR) data to determine magnitude of subsidence in area of the town ofWieliczka. The town is home to a unique salt mine, over 700 years old, one of the best known tourist attractions in Poland. Each year the mine is visited by about 1 million tourists from all over the world and in 1978 UNESCO placed it on its first International List of theWorld Cultural and Natural Heritage. There is direct evidence that the mining has been influencing stability of ground and buildings in the town, which is located above the mine. The application of the PSI SPINUA technique made it possible to identify large number of radar targets (with density exceeding 100 PS/km2), suitable for monitoring ground motion in the Wieliczka area. The results show continuous subsidence with average annual movements ranging from a few millimeter per year to 24 mm/yr in the period 1992–2000. The detected subsiding zone very well corresponds to the extent of the underground salt mine. There are also indications of possible connections between the mine-induced subsidence and the presence of the old large landslides occurring on the north-facing slopes south of the Wieliczka Salt Mine.
[Nit.IGARSS2009] Nitti, D.O., Nutricato, R., Bovenga F., Rana F., Conte, D., Guerriero, L. and Milillo, G., “Quantitative Analysis of Stripmap And Spotlight SAR Interferometry with CosmoSkyMed constellation.”. In Proceedings of the IEEE International Geoscience and Remote Sensing Symposium. July 13-17, 2009. Cape Town, South Africa. DOI: 10.1109/IGARSS.2009.5418249. E-ISBN: 978-1-4244-3395-7. Print ISBN: 978-1-4244-3394-0. ISSN: 2153-6996. eISSN: 2153-7003. Scopus: 2-s2.0-77951142859. WOS:000281054100298
This work is focused on the phase validation of interferograms obtained by combining COSMO-SkyMed SAR images acquired by a single satellite (temporal baseline coincident with the orbital repeat cycle) or even by two satellites of the SAR constellation in equi-phased configuration on the orbital plane (temporal baseline: 8 days), thus minimizing the temporal decorrelation. Both qualitative and quantitative analyses have been therefore carried out for HI (HIMAGE: stripmap, single polarization) and S2 (enhanced spotlight) imaging modes, in order to proof whether or not COSMO-SkyMed constellation is well suited for SAR interferometry.
Planimetry and heights over Railway Yard "S. Lorenzo" in Rome provided by RFI spa – Dir. Comp. Infr. Roma. All CSK images for the two italian test sites provided by ASI under the ASI - INNOVA contract n. I/038/07/0 and I AA. High precision laser scanning Digital Height Model over Langnau provided by Amt für Geoinformation, Bau-, Verkehrs und Energiedirektion des Kantons Bern. TerraSAR data ((c) Infoterra) are provided by DLR under a Scientific Use License for the proposal MTH0397.
[Nit.SPIE2009] D. O. Nitti, R. Nutricato, F. Bovenga, A. Refice, M.T. Chiaradia and L. Guerriero, “TerraSAR-X InSAR multi-pass analysis on Venice (Italy)”. In Proceedings of SPIE Remote Sensing, 31 August-3 September 2009, Berlin, Germany. DOI: 10.1117/12.832047. ISBN: 9780819477828. ISSN 0277-786X. Scopus: 2-s2.0-70350433000.
The TerraSAR-X mission, launched in 2007, carries a new X-band Synthetic Aperture Radar (SAR) sensor optimally suited for SAR interferometry (InSAR), thus allowing very promising application of InSAR techniques for the risk assessment on areas with hydrogeological instability and especially for multi-temporal analysis, such as Persistent Scatterer Interferometry (PSI) techniques, originally developed at Politecnico di Milano. The SPINUA (Stable Point INterferometry over Unurbanised Areas) technique is a PSI processing methodology which has originally been developed with the aim of detection and monitoring of coherent PS targets in non or scarcely-urbanized areas. The main goal of the present work is to describe successful applications of the SPINUA PSI technique in processing X-band data. Venice has been selected as test site since it is in favorable settings for PSI investigations (urban area containing many potential coherent targets such as buildings) and in view of the availability of a long temporal series of TerraSAR-X stripmap acquisitions (27 scenes in all). The Venice Lagoon is affected by land sinking phenomena, whose origins are both natural and man-induced. The subsidence of Venice has been intensively studied for decades by determining land displacements through traditional monitoring techniques (leveling and GPS) and, recently, by processing stacks of ERS/ENVISAT SAR data. The present work is focused on an independent assessment of application of PSI techniques to TerraSAR-X stripmap data for monitoring the stability of the Venice area. Thanks to its orbital repeat cycle of only 11 days, less than a third of ERS/ENVISAT missions, the maximum displacement rate that can be unambiguously detected along the Line-of-Sight (LOS) with TerraSAR-X SAR data through PSI techniques is expected to be about twice the corresponding value of ESA missions, being directly proportional to the sensor wavelength and inversely proportional to the revisit time. When monitoring displacement phenomena which are known to be within the rate limits, the increased repeat cycle of TerraSAR-X offers the opportunity to decimate the stack of TerraSAR-X data, e.g. by doubling the temporal baseline between subsequent acquisitions. This strategy can be adopted for reducing both economic and computational processing costs. In the present work, the displacement rate maps obtained through SPINUA with and without decimation of the number of Single Look Complex (SLC) acquisitions are compared. In particular, it is shown that with high spatial resolution SAR data, reliable displacement maps could be estimated through PSI techniques with a number of SLCs much lower than in C-band.
TerraSAR-X data (Infoterra) are provided by Infoterra in the frame of the TerraSAR-X General AO ProjectMTH0432 (PI Maria Teresa Chiaradia).
[Nit.SPIE2009b] D. O. Nitti, F. Bovenga, R. Nutricato, F. Rana, C. D’Aprile, P. Frattini, G. Crosta, M. T. Chiaradia, G. Ober and L. Candela, “C- and X-band multi-pass InSAR analysis over Alpine areas (ITALY)”. In Proceedings of SPIE Remote Sensing, 31 August-3 September 2009, Berlin, Germany. DOI: 10.1117/12.849210. ISBN: 9780819477828. ISSN 0277-786X. Scopus: 2-s2.0-70350458742
In the present work we present first results of ground deformation measurements inferred through repeat-pass Synthetic Aperture Radar (SAR) Interferometry (InSAR) in C- and X-band over an Italian Alpine area, in Lombardia region. The activity was carried out in the framework of the MORFEO (MOnitoraggio e Rischio da Frana mediante dati EO) project founded by the Italian Spatial Agency (ASI) and dedicated to landslide risk assessment. A number of areas affected by hydrogeological instabilities have been selected and studied in detail by processing both C- and X-band SAR data through SPINUA, a Persistent Scatterer like algorithm. In particular, two stacks of 30 Ascending ENVISAT SAR images (October 2004 – January 2009) and 32 Descending ENVISAT SAR images (December 2004 – January 2009) have been independently processed to ensures the detection of movements occurring along both west and east facing slopes. Moreover, further deformation measurements have been obtained by processing a set of 12 COSMO-SkyMED ascending HIMAGE interferometric acquisitions (Satellite CSKS1; Beam HI-03; POL: HH; Incidence Angle: 29°) provided by ASI. After a proper tuning of the interferometric algorithmic solutions, even with very high normal baselines, we are able to appreciate the potentials of X-band interferometry. Although the number of COSMO-SkyMED acquisitions is quite limited, spanning a period of only 10 months (August 2008 – June 2009), SPINUA was capable to retrieve preliminary ground displacement patterns that are in good agreement with those previously estimated in . Quite impressive is to realize that, because of the tenfold improved resolution of X-band images, multi-temporal InSAR techniques may be successfully applied for the estimation of the displacement maps with a number of acquisitions much lower than in . InSAR-derived displacements provided on areas of hydrogeological interest are going to be validated in the framework of MORFEO project by the geological partnership thanks to the availability of ground truths. In the present work, we present the results obtained on the towns of Garzeno, Catasco and Germasino which are affected by landslide phenomena. We provide a first validation by comparing the deformation maps derived from ENVISAT data, from COSMO-SkyMED X-band data as well as from ERS and RADARSAT data freely available on the GeoIFFI web-catalogue.
ENVISAT and COSMO-SkyMED images were provided respectively by ESA and ASI in the framework of the MORFEO project (ASI Contract n. I/045/07/0).
[Nit.FRINGE2009] D.O.Nitti, F. Bovenga, F.Rana, R. Nutricato, M. Tragni, M. T. Chiaradia, G. Ober, L. Candela, “On the use of C- and X-band SAR data for studying the ground deformations induced by the April 6th, 2009 Earthquake in Abruzzo”. In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
In the study both DInSAR and PSI techniques have been used to generate co-seismic and post-seismic deformation patterns for the Mw=6.3 earthquake which the Abruzzo region in Italy on April 6th, 2009. In particular, we used SAR data acquired in (wavelength of 5.6 cm) by the European Space Agency (ESA) ENVISAT satellite, and X-band (wavelength of 3.1 cm) by the Italian Space Agency (ASI) constellation COSMO-SkyMed (CSK) as well as by the German Space Agency (DLR) TerraSAR-X (TSX). Concerning the co-seismic deformation, is has been studied by processing, through standard DInSAR technique, SAR data with different values of wavelength, spatial as well as incident angles. A comparative analysis of interferometric fringe patterns is presented. Due to the low deformation rate involved, the study of post-seismic events requires the use of a multi-temporal InSAR approach. Thanks to the availability of a stacks of ascending CSK acquisitions, ad hoc programmed by ASI on the area stricken by the earthquake, it was possible to infer post-seismic deformation map through SPINUA PSI-like InSAR analysis. A first validation of these results is also presented.
The ENVISAT satellite images were made freely available by ESA (dataset SAR Italy earthquake April 2009). The processing of COSMO-SkyMED data was carried out in the framework of MORFEO project (ASI Contract n. I/045/07/0).
[Nut.FRINGE2009] R. Nutricato, D. O. Nitti, F. Bovenga, F. Rana, C. D’Aprile, P. Frattini, G. Crosta, G. Venuti, M. T. Chiaradia, G. Ober, L. Candela, “MORFEO PROJECT: C- and X-Band SAR interferometric analysis over Alpine regions (Italy)”. In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
In the present work we present first results of ground deformation measurements inferred through repeat-pass Synthetic Aperture Radar (SAR) Interferometry (In- SAR) in C- and X-band over an Italian Alpine area, in Lombardia region. The activity was carried out in the framework of the MORFEO (MOnitoraggio e Rischio da Frana mediante dati EO) project, founded by the Italian Spatial Agency (ASI) and dedicated to landslide risk assessment. A number of areas affected by hydrogeological instabilities have been selected and studied in detail by processing both C- and X-band SAR data through SPINUA, a Persistent Scatterer like algorithm. InSAR-derived displacements provided on areas of hydrogeological interest are going to be validated in the framework of MORFEO project by the geological partnership thanks to the availability of ground truths. In the present work, we present the results obtained for test around the towns of Garzeno and Bindo which are both affected by landslide phenomena. For the Garzeno case study we provide also a comparison between the deformation maps derived from ENVISAT and the preliminary results obtained with a limited number of COSMO-SkyMED images, as well as with ERS and RADARSAT PS maps freely available on the GeoIFFIweb-catalogue.
ENVISAT and COSMO-SkyMED images were provided respectively by ESA and ASI in the framework of the MORFEO project (ASI Contract n. I/045/07/0).
[Nit.FRINGE2009b] D. O. Nitti, L. De Vitis, F. Bovenga, R. Nutricato, A. Refice , J. Wasowski, “Multi-temporal L-band SAR interferometry confirms C- band spatial patterns of subsidence in the ancient Wieliczka salt mine (UNESCO heritage site, Poland).”. In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
This work presents first results of interferometric processing of ALOS PALSAR Single Look Complex SAR images (Fine Beam Mode), concerning ground deformations in the Wieliczka Salt Mine area, a few km from Cracow, Poland. It follows a recent Persistent Scatterers SAR Interferometry (PSI) analysis on this area, obtained by processing several tens of ERS satellite images covering the period 1992-2000. ERS results revealed the presence of a few kilometres long, slowly subsiding zone corresponding very well to the extent of the underground salt mine. The present work aims to extend the analysis by exploiting ALOS-PALSAR data especially for the rural areas, which neighbour the salt mine but lack PS in , relying on the lower sensitivity to temporal decorrelation of L-band w.r.t. radar data. This work shows and compares ERS and PALSAR (Fine Beam) ground displacement patterns detected over the Wieliczka Salt Mine area through the application of multi-temporal interferometric techniques.
ERS and PALSAR satellite images were provided by ESA under the ALOS ADEN AO 3595 project.
[Cza.FRINGE2009] M. Czarnogórska, M. Graniczny, S. Uscinowicz, R. Nutricato, S. Triggiani, D. O. Nitti, F. Bovenga, J. Wasowski, “PSI analysis of ground deformations along the South-Western coast of the Gulf of Gdansk (Poland).”. In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
We use over 40 descending ERS-1/2 SLC (Frame = 2511 , Track = 36) images from the period 1995 – 2001 and the SPINUA (Stable Point Interferometry over Unurbanised Areas) Persistent Scatterers Interferometry (PSI) processing technique to study Earth surface deformations along the SW coast of the Gulf of Gdansk, along the SE part of the Baltic Sea. The area of interest (AOI) includes few cities and several towns, villages and harbours. The low lying coastal areas of the SW part of the Gulf of Gdansk are at risk of floods and marine erosion. It is expected that this problem can be exacerbated by the ongoing sea level rise and possibly by crustal movements (subsidence) reported in the literature. The PSI results, however, did not reveal the presence of a regional scale, spatially consistent pattern of displacements. It is likely that any crustal deformations in the AOI simply do not exceed +-2 mm/year, which is the velocity threshold we assumed to distinguish between moving and non-moving radar targets. Nevertheless, significant downward displacements, amounting to several mm/year, are locally present in the coastal zone east of Gdansk that belongs to the Vistula river delta-alluvial plain system, as well as in the inland area west of the cities of Gdansk and Sopot. It is apparent that in all these cases the movements reflect mainly differential settlements of buildings and engineering infrastructure, which have recently been built in the areas including clay-rich, compressible sediments. Indeed, one of the highest subsidence rates (- 12 mm/year) was observed in the Gdansk petroleum refinery constructed on alluvial sediments. Thus the anthropogenic loading and consolidation of the recent deposits can locally be an important factor causing ground settlements. Importantly, for the most part the urban areas of the main cities (Gdansk, Gdynia and Sopot) result to be stable
ERS SAR data were provided by ESA through CAT-1 project n. 4416.
[Bov.FRINGE2009] F. Bovenga, V. M. Giacovazzo, A. Refice, N. Veneziani, R. Vitulli, "Multi-chromatic analysis of InSAR data: validation and potential". In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
The present paper presents the results of the application of Multi Chromatic Analysis (MCA) for height retrieval by processing both AES-1 airborne data and satellite TerraSAR-X data. In particular, a test of the robustness of the MCA technique with respect to total processed bandwidth has been performed through comparison of results from datasets with bandwidths spanning form 100 to 400 MHz. A first validation of the mentioned technique has been carried out by comparing the retrieved heights w.r.t. ground elevation from external SRTM DEM, as well as by verifying the reliability of the fringe classifications based on the integer number of phase cycles computed through MCA. Results are presented and commented by addressing potential and limitation of the technique.
Work supported by ESA ESTEC Contr. N.21319/07/NL/HE. Sample AES-1 data courtesy of SARMAP, while TerraSAR-X images are provided by DLR under a Scientific Use License for proposal MTH0397. The authors thank Ing. Davide Nitti from Politecnico di Bari for his help in pre-processing TSX data.
[Red.FRINGE2009] A. Redavid, F. Bovenga, "DARIS (Deformation Analysis using Recursive Interferometric Systems) A new algorithm for displacement measurements though SAR interferometry". In Proceedings of the Workshop Fringe 2009 - Advances in the Science and Applications of SAR Interferometry, November 30 - December 4, 2009, ESA/ESRIN, Frascati, Italy. Vol. ESA SP-677. ISBN 978-92-9221-241-4. ISSN 1609-042X.
In the present work we describe a new and alternative repeat-pass interferometry algorithm designed and developed with the aim to: i) increase the robustness wrt to noise by increasing the number of differential interferograms and consequently the information redundancy; ii) guarantee high performances in the detection of non linear deformation without the need of specifying in input a particular cinematic model. The starting point is a previous paper dedicated to the optimization of the InSAR coregistration by finding an ad hoc path between the images which minimizes the expected total decorrelation as in the SABS-like approaches. The main difference wrt the PS-like algorithms is the use of couples of images which potentially can show high spatial coherence and, which are neglected by the standard PSI processing. The present work presents a detailed description of the algorithm processing steps as well as the results obtained by processing simulated InSAR data with the aim to evaluate the algorithm performances. Moreover, the algorithm has been also applied on a real test case in Poland, to study the subsidence affecting the Wieliczka Salt Mine. A cross validation wrt SPINUA PSI-like algorithm has been carried out by comparing the resultant displacement fields.
Work supported by MORFEO project (ASI Contract n.I/045/07/0). The ERS satellite images were provided by ESA under the ALOS ADEN 3595 project. The authors thank Ing. Davide Oscar Nitti and Ing. Leonardo De Vitis from Politectnico di Bari for the help in preprocessing real SAR data.
National Conference Proceedings
[Nit.ASITA2009] D. O. Nitti, F. Rana, F. Bovenga, R. Nutricato, M. Tragni, M. T. Chiaradia, G. Ober, L. Candela, “Analisi del sisma del 6 Aprile 2009 in Abruzzo con tecniche di Interferometria SAR differenziale”. Atti 13a Conferenza Nazionale ASITA, 1 – 4 dic. 2009, Fiera del Levante Bari, Italia. ISBN: 978-88-903132-2-6.
Synthetic Aperture Radar (SAR) sensors can provide useful support to the analysis and managing of the natural risks. In particular, SAR Interferometry (InSAR), thanks to its large-scale view area coverage of the deformation field, provides useful measurements for damage assessment of seismic events and fault modelling. The present study is aimed to the application of InSAR techniques for obtaining the co-seismic deformation pattern and inferring the fault model parameters for the Mw=6.3 earthquake which struck the Abruzzo region in Italy on April 6th, 2009. In particular, we used SAR data acquired in (wavelength of 5.6 cm) by the European Space Agency (ESA) ENVISAT satellite, and X-band (wavelength of 3.1 cm) by the German Space Agency (DLR) TerraSAR-X as well as by the Italian Space Agency (ASI) constellation COSMO-SkyMed. Through the SPINUA processing chain, the co-seismic differential interferograms were generated which record the deformation induced by the seismic event. In the present work we present a comparative analysis of interferometric fringe patterns obtained with different values of wavelength, spatial resolution as well as incident angles.
Gli autori ringraziano l’Agenzia Spaziale Europea per aver messo a disposizione il dataset SAR Italy earthquake April 2009. Le immagini COSMO-SkyMED sono state elaborate nell’ambito del progetto MORFEO (contratto ASI n. I/045/07/0)
[Agl.ASITA2009] F. Agliardi, F. Bovenga, L. Candela, M. T. Chiaradia, G.B. Crosta, C. D’Aprile, G. Fornaro, P. Frattini, M. Gilardoni, F. Guzzetti, R. Lanari, D. O. Nitti, R. Nutricato, G. Ober, F. Rana, G. Venuti, G. Zeni, “Attività di elaborazione di dati EO SAR su aree in frana nell’ambito del progetto ASI MORFEO”. Atti 13a Conferenza Nazionale ASITA, 1 – 4 dicembre 2009, Fiera del Levante Bari, Italia. ISBN: 978-88-903132-2-6.
In the framework of MORFEO project, financed by the Italian Space Agency (ASI), a study is currently under way to estimate and validate monitoring technologies of deformations with SAR data, to the implementation of a pre-operational service supporting the Civil Protection Department in landslide risk monitoring. The study on ground deformations is performed in MORFEO by applying two different technologies: SBAS developed by CNR-IREA in Naples and SPINUA developed by Politecnico of Bari. These technologies work with SAR data in and the use of X-band data acquired by COSMO/SKY-MED is under trial. In particular the present report describes the generation and validation activities of EO SAR products (Synthetic Aperture Radar) obtained in landslide areas in Lombardia and Umbria by using ascending and descending passages of ENVISAT satellite. The results obtained in Umbria highlight the presence of deformation phenomena in the area corresponding to the landslide region in Ivancich (Assisi). A general accordance between GPS and SAR sets results by the comparison. In Lombardia GPS deformation time sets have been estimated for SAR data validation. This has highlighted the potential and limits of SAR interferometric techniques for landslide monitoring in an alpine context. Moreover, a first multi-temporal interferometric analysis in X-band has been carried out through the SPINUA algorithm. Preliminary results over the area of GARZENO (COMO) show that even with a limited number of COSMO/SkyMED images, there is a good agreement with linear displacement rate maps estimated in . An accurate investigation shall be feasible as soon as a consistent number of COSMO/SkyMED acquisitions is available (not less than 25-30).
This work was supported by ASI, under Contract No. I/045/07/0 “MOnitoraggio del Rishio da Frana mediante dati EO (MORFEO)”.
[Abb.ASITA2009] C. Abbattista, R. Nutricato, D. O. Nitti, G. Ober, L. Candela, “Utilizzo congiunto di tecniche e dati SAR con dati in situ nel progetto ASI MORFEO (MOnitoraggio e Rischio da Frana mediante dati EO)”. Atti 13a Conferenza Nazionale ASITA, 1 – 4 dicembre 2009, Fiera del Levante Bari, Italia. ISBN: 978-88-903132-2-6.
The three year MORFEO pilot project, commissioned by the Italian Space Agency (ASI), implements a Decision Support System for the Civil Protection about the Landslides Risk. The system is based on the use of multi-mission Earth Observation data combined with traditional in situ data and technologies. The project provides the Italian Civil Protection Department with some tools allowing the landslides identification and mapping, a better spatial and temporal forecast of the landslides and the monitoring of landslides movements at local, province or regional scale. This paper describes the MORFEO SAR sub system, whose aim is to generate products for the civil protection thanks to the synergic use of GPS, optic EO and SAR (Synthetic Aperture Radar ) EO data, by the exploitation of new interferometric techniques. The subsystem receives as inputs C, L and X-band SAR data and by using the SPINUA processor produces warping maps as collections of Persistent Scatterers (PS) points. Combining those maps with Optic EO data and GPS data, is possible to generate high level products like PS coverage maps, contextual maps, statistical products and correlation maps.
[DeA.NuovoSag2008] A. De Angelis, N. Giglietto, L. Guerriero, E. Menichetti, P. Spinelli, S. Stramaglia, "Domenico Pacini, un pioniere dimenticato dello studio dei raggi cosmici". Il Nuovo Saggiatore Vol. 24, No 3-4, pag. 70-74 (2008). ISSN 0393-4578 (print). E-ISSN 1827-6148.
Si ringrazia l'Università di Bari per l'aiuto fornito nel ritrovare materiale e documenti relativi a D. Pacini, il Dipartimento Interateneo di Fisica di Bari per la collaborazione nell'organizzare la giornata commemorativa tenutasi a Bari il 17 aprile 2007, e quanti hanno collaborato a questa in particolare F. Guerra e Robotti, i quali hanno contribuito nella ricerca di documenti presso completando il quadro “sociologico” del contesto in cui operò Pacini e quanti hanno partecipato a questo evento.
International Conference Proceedings
[Was.ISL2008] Wasowsky, J., Bovenga, F., Nutricato, R., Nitti, D.O., Refice, A. and Casarano, D., “Landslide-prone towns in Daunia (Italy): PS interferometry-based investigation”. In: Landslides And Engineered Slopes: From The Past To The Future. Proceedings of the 10th International Symposium On Landslides And Engineered Slopes. June 30 – July 4, 2008. Xi'an, China. vol. 1, p. 513-518, Chen, Z; Zhang, JM; Li, ZK; Wu, FQ; Ho, K, Print ISBN: 978-0-415-41196-7. eBook ISBN: 978-0-203-88528-4. DOI: 10.1201/9780203885284-c58. WOS:000266239200058
Persistent Scatterers Interferometry (PSI) and satellite radar imagery can be used to detect very slow displacements (mm-cm per year) of targets (PS) exhibiting coherent radar backscattering properties (mainly man-made structures). Here we present results of the PSI application to the Daunia Apennines, which include many hilltop towns affected by landslides. Examples from the towns Casalnuovo Monterotaro and Pietramontecorvino are used to illustrate that the interpretation of PS data on urbanised slopes can be difficult, because their movements may arise from a variety of processes: i) volumetric strains within soils, ii) natural or anthropogenic subsidence or uplift, iii) settlement of engineering structures, iv) deterioration of man-made structures, v) extremely slow slope deformations that may or may not lead to failure. Where true landslide movements are detected, they likely regard long-term post-failure displacements involving clay-rich materials.
This work was supported in part by the European Community (Contract No. EVGI 2001-00055—Project LEWIS). Images were provided by ESA under the CAT-1 project 2653.
[Nit.SPIE2008] Nitti D.O., Hanssen R.F., Refice A., Bovenga F., Milillo G. and Nutricato R., “Evaluation of DEM-assisted SAR coregistration”. In Proceedings of SPIE Remote Sensing, 15–18 Sept. 2008. Cardiff, Wales, United Kingdom (2008). DOI: 10.1117/12.802767. ISBN: 9780819473400. ISSN 0277-786X. Scopus: 2-s2.0-57649112728
Image alignment is without doubt the most crucial step in SAR Interferometry. Interferogram formation requires images to be coregistered with an accuracy of better than 1/8 pixel to avoid significant loss of phase coherence. Conventional interferometric precise coregistration methods for full-resolution SAR data (Single-Look Complex imagery, or SLC) are based on the cross-correlation of the SLC data, either in the original complex form or as squared amplitudes. Offset vectors in slant range and azimuth directions are computed on a large number of windows, according to the estimated correlation peaks. Then, a two-dimensional polynomial of a certain degree is usually chosen as warp function and the polynomial parameters are estimated through LMS fit from the shifts measured on the image windows. In case of rough topography and long baselines, the polynomial approximation for the warp function becomes inaccurate, leading to local misregistrations. Moreover, these effects increase with the spatial resolution and then with the sampling frequency of the sensor, as first results on TerraSAR-X interferometry confirm. An improved, DEM-assisted image coregistration procedure can be adopted for providing higher-order prediction of the offset vectors. Instead of estimating the shifts on a limited number of patches and using a polynomial approximation for the transformation, this approach computes pixel by pixel the correspondence between master and slave by using the orbital data and a reference DEM. This study assesses the performance of this approach with respect to the standard procedure. In particular, both analytical relationships and simulations will evaluate the impact of the finite vertical accuracy of the DEM on the final coregistration precision for different radar postings and relative positions of satellites. The two approaches are compared by processing real data at different carrier frequencies and using the interferometric coherence as quality figure.
TerraSAR data ((c) Infoterra) were kindly provided by Infoterra and acquired (Sales Order Number 5832) in the framework of the SAMAAV project (Study And Monitoring of Active African Volcanoes) coordinated by Royal Museum for Central Africa in Belgium and National Museum of Natural History of Luxembourg (contacts: francois.kervyn@africamuseum.be and nicolas.doreye@ecgs.lu). PALSAR images provided by European Space Agency (ESA) under the ALOS ADEN AO 3595 project. ERS data provided by ESA under the CAT-1 project n.2653. The authors thank Antonio Valentino of the Consortium Innova (Italy) for the fruitful collaboration.
[Nit.ALOSPI2008] Nitti, D.O., Bovenga, F., Refice, A., Wasowski, J., Conte, D., Nutricato, R., “L- and SAR Interferometry analysis of the Wieliczka salt mine area (UNESCO heritage site, Poland)”. In Proceedings of the 2008 Joint PI Symposium of the ALOS Data Nodes. 3 – 7 Nov., 2008. Rhodes, Greece (2008). Vol.: ESA-SP 664. ISBN: 978-92-9221-228-5. ISSN 1609-042X. Scopus: 2-s2.0-77955176893
This work presents first results of interferometric processing of ALOS PALSAR Single Look Complex SAR images (Stripmap Single Polarization Mode), concerning ground deformations in the Wieliczka Salt Mine area, a few km from Cracow, Poland. It follows a recent Persistent Scatterers SAR Interferometry (PSI) analysis on this area, obtained by processing several tens of ERS satellite images covering the period 1992-2000. The results revealed the presence of a few kilometres long, slowly subsiding zone corresponding very well to the extent of the underground salt mine. The present work aims to extend the analysis by exploiting ALOS-PALSAR data especially for the neighbouring rural areas, relying on the lower sensitivity to temporal decorrelation of L-band w.r.t. radar data. Use of L band data is of interest because it could allow detecting faster ground movements related to sudden subsidence events that have occasionally occurred in the recent past. One such event, reported in the 1990’s, caused ground displacements locally exceeding 3 m. Furthermore, with L-band SAR data some useful information can be obtained for the rural areas, which neighbour the salt mine but lack PS. We present results obtained from Fine Beam, HH Single Polarization Mode (FBS), 34.3° Off-Nadir look-angle SAR images. The night acquisition time of FBS PALSAR images mitigates the atmospheric phase screen in each interferogram. No clear evidence of displacements is found on ALOS interferograms spanning about 1 year. The relatively high coherence shown by the interferograms allows easier unwrapping of the differential interferometric phase, aiding further statistical investigations on the spatial properties of the atmospheric signal. We also present considerations concerning some processing aspects of ALOS data, as well as a preliminary comparison between the L-band and differential interferometric phase behaviour.
PALSAR satellite images were provided by ESA under the ALOS ADEN AO 3595 project.
[Mat.IGARSS2008] R. Matarrese, A. Morea, K. Tijani, V. De Pasquale, M.T. Chiaradia, G. Pasquariello “A Specialized Support Vector Machine Coastal Water Chlorophyll Retrieval From Water Leaving Reflectances”. Proceedings of IGARSS 2008, Poster Session, July 6-11, 2008. Boston, Massachussetts, U.S.A. DOI: 10.1109/IGARSS.2008.4779871. E-ISBN: 978-1-4244-2808-3. Print ISBN: 978-1-4244-2807-6.
Ocean colors observed by satellite are the measure of the water leaving reflectance of the investigated area, and vary according to the concentration of water’s constituents. The relationship between satellite-derived ocean colors and chlorophyll a concentrations has been studied for several decades [1-3], and several model-based estimation algorithms have been proposed. Analytical models take account of all parameters relating water leaving reflectance with chlorophyll concentration [4]. In empirical approaches remote sensed data is related to the chlorophyll concentration by interpolation techniques applied to a set of training samples. Several neural networks based algorithms have been proposed for the empirical approach [5-10]. In [11] a performance evaluation between several empirical approaches in inversion problems, shown that the use of the support vector machine (SVM) can improve the state of the art neural network solution. In this paper we propose a SVM specialized on Apulian coastal zones showing very encouraging results.
This work has been supported by MIUR (Ministero dell’Università e della Ricerca), within the framework of IMCA project (Integrated Monitoring of Coastal Areas).
[Mat.IGARSS2008b] R. Matarrese, M. Acquaro, A. Morea, K.Tijani, M.T.Chiaradia “Applications Of Remote Sensing Techniques For Mapping Posidonia Oceanica Meadows”. Proceedings of IGARSS 2008, Poster Session, July 6-11, 2008. Boston, Massachussetts, U.S.A. DOI: 10.1109/IGARSS.2008.4779870. E-ISBN: 978-1-4244-2808-3. Print ISBN: 978-1-4244-2807-6.
Posidonia Oceanica is a marine phanerogam characterizing an ultimate succession stage (climax) on sandy bottoms in the Mediterranean Sea. In particular, Posidonia Oceanica ecosystems are an important element in improving the water quality of coastal waters [1], [2]. Producing thematic maps of seagrass communities from remote sensing data is a multistep process. First, a preprocessing phase to correct satellite images. The second step is the classification phase. Subsequently the postclassification phase have to improve the accuracy of the results. In this study, Posidonia Oceanica meadows maps of Taranto Gulf, Ionian Sea, in 2001, 2002, and 2004, are produced from Ikonos, ETM+ and ASTER images. A comparison with ground truth measurements in the Ionian Sea shows the advantages and the limits of each approach.
This work has been supported by MIUR (Ministero dell’Università e della Ricerca), within the framework of IMCA project (Integrated Monitoring of Coastal Areas).
National Conference Proceedings
[Chi.ADB2008] Chiaradia M.T., Francioso R., Matarrese R., Petrillo A. F., Ranieri G., Urrutia C. (2008) – Estrazione Semi-Automatica Della Linea Di Costa Da Immagini Satellitari Ad Alta Risoluzione: Valutazione Ed Applicabilità. Collana Editoriale Di Studi E Ricerche Dell’autorità Di Bacino Della Basilicata, N. 9.
La conoscenza della posizione della linea di riva è uno degli elementi fondamentali nella pianificazione della fascia costiera. È noto che essa subisce spostamenti di carattere stagionale, ma che mediamente tende ad una situazione di equilibrio, a meno di modificazioni del trasporto solido costiero determinato da azioni antropiche nei bacini idrografici in cui è inserita l’unità fisiografica del litorale in esame o dalla realizzazione di opere a mare. Da qui la necessità di supportare la pianificazione della fascia costiera con il monitoraggio della linea di riva con rilievi almeno semestrali al fine di correggere le variabilità stagionali o le singolarità indotte da mareggiate intense. La linea di riva normalmente si ricava da rilievi tradizionali in situ, tuttavia non mancano esempi di estrazione da cartografia ortografica e da immagini satellitari. Uno degli obbiettivi del progetto IMCA finanziato con fondi PON, è stato quello di attivare una procedura semi-automatica per l’estrazione della posizione della linea di riva da immagini satellitari ad alta risoluzione. Nel presente lavoro è illustrata la tecnica utilizzata per questa procedura, i risultati ottenuti in un caso reale di applicazione e la valutazione della loro affidabilità.
This work has been supported by MIUR (Ministero dell’Università e della Ricerca), within the framework of IMCA project (Integrated Monitoring of Coastal Areas).
Conference Abstracts
[Dou.CeTeM2008] Doubell, M., Fasano, L., Ferri, V., Lorè, V.A., Milillo, G., Nitti D.O., Nutricato, R., Conte, D., Bovenga, F., Valentino, A., “COSMO SKYMED qualitative analysis and examples using “GSDVIEW” open source graphic tool and interferometric measurements”. XIV Annual Meeting CeTeM / V Workshop AIT / XIV MECSA Day on Microwave Engineering. Microwave Remote Sensing: systems, propagation, algorithms: from technologies to applications. 23-24 Oct., 2008. Rome, Italy (2008).
The COSMO-SkyMed constellation will acquire data from its four SAR satellites in several image modes, and will generate focused data products. Presently, two satellites are in orbit. The constellation will be completed by 2009. In this paper we detail the analysis and experimentation carried out with the first COSMO-SkyMed real SAR data. A qualitative analysis and in part a quantitative analysis have been carried out with the support of the correspondent optical images. The steps used have been to: 1. Individualize the targets and the characteristics of the SAR data; 2. Verify the characteristics of the data, of the satellite configuration and of the SAR; 3. Interpret the data and the connected phenomena; 4. Carry out both qualitative and quantitative analysis on InSAR phase with preliminary height measurements. The operational instrument with which the COSMO-SkyMed images have been elaborated has been the "GSDView" Open Source Tool, currently under development by INNOVA Consorzio per l'Informatica la Telematica under an ASI (Italian Space Agency) contract. Various contexts have been analyzed within the SAR images, with specific attention to human interest areas, such as: metropolitan areas, ports and coasts and agricultural areas. The data set used for the analysis has been predominantly from SCS (Single-look Complex Slant), DGM (Detected Ground Multilook), GEC (Geocoded Ellipsoid Corrected) and GTC (Geocoded Terrain Corrected) products acquired by the COSMO-SkyMed satellites SAR1 and/or SAR2 in StripMap and Spotlight acquisition modes. The completed analysis shows the great potential of the sensor. The COSMO-SkyMed data regards the possible use in Earth Observation (EO) applications such as Change Detection (CD), Moving Target Detection (MTD), and Interferometry. The interferometric analysis first verified the impact of an improved tool for coregistering SAR images that uses DEM and orbital information instead of polynomial models. This approach results in better performance for high resolution CSK images especially in areas with rough topography. Once the InSAR processing chain was properly updated, interferograms were computed by using both CSK-1 and CSK-2 data and first height retrieval experiments were carried out. The higher resolution of CSK images and the short revisitation rate of the full constellation will ensure a more detailed InSAR phase allowing new potential applications (urban applications, precise DEM, etc.). The applications studied are of significant importance in both Military and Civil spheres because they consent target detection with geometric and physical characteristics. The stability and high resolution characteristics of the sensor together with the fast revisit rate foreseen for the COSMO-SkyMed system will allow to define new high level product categories and make possible new innovative applications for the EO field.
Attività realizzata da GAP nell’ambito del Contratto ASI - INNOVA n I/038/07/0 e I AA
[DeP.IGARSS2008] V. De Pasquale, R. Matarrese, G. Pasquariello, M.T. Chiaradia, "Validation of chlorophyll concentration algorithms in Apulian coastal areas". Abstracts of IGARSS 2008, poster session, July 6-11, 2008. Boston, Massachussetts, U.S.A. http://www.igarss08.org/Abstracts/pdfs/3694.pdf
Monitoring and managing small coastal ecosystems require a considerable understanding of temporal dynamics of biophysical factors describing coastal water systems. For this reason, daily observation from space could be a very efficient tool. For this purpose, high resolution, multispectral satellite data have been successfully applied in the detection of chemical, biological and physical processes happening in coastal waters. However, monitoring coastal waters using the existing satellite instruments, is a challenging task which requires very sophisticate procedures. We know that in open oceans, case I waters, phytoplankton is the principal agent responsible for the optical properties of waters. Instead, the optical properties of shallow and coastal waters, case II waters, are influenced not only by phytoplankton, but also by other substances, generally classified as suspended inorganic particles and yellow substance [1]. In the framework of IMCA project (Integrated Monitoring of Coastal Area) an important set of in situ measurements has been carried out. Beside lab-measurements of water quality parameters and their inherent optical properties, a set of radiometric measurements have been performed. This measurements consist of downwelling irradiance above water, and in water profiles of downwelling irradiance, upwelling radiance, fluorimetric chlorophyll-a concentration, temperature and other ancillary quantities. These measurements are performed using the Satlantic Profile II, a free fall profiler with OCR- 507 I and OCR-507 R radiometers connected. The areas of interest are located in the south-east of Italy in the region of Apulia. In this region, three sites have been selected: 1) Taranto seas on the Ionian Sea. This site is characterized by a strong human activity for the presence of important industrial settlements with an high traffic commercial port and a base of Italian Military Marine; 2) Margherita di Savoia and estuarine of Ofanto river on the Adriatic Sea. The waters of this area are very turbid due to the presence of the river and for some industrial settlements near the small town; 3) Tremiti islands on the Adriatic sea, an important marine protected area characterized by clear water conditions. In these areas a total of 25 stations located within 3 km from the shore have been selected, and the measurements have been performed about twice per month, according on the cloud free satellite overpasses from Spring 2006 to Spring 2008. The aim of this paper is the validation of some bio-optical algorithms for the retrieval of chlorophyll-a concentration. The remote sensing reflectances derived from in situ measurements have been used as input for the algorithms, and the resulting chlorophyll concentrations have been compared to the one measured by the fluorimeter and with the one derived by the water samples using the HPLC technique. Three algorithms have been selected. The first one is a simple empirical algorithm[2]. It has been selected to test the hypothesis that the Tremiti site could be considered as case I area. The other two algorithms are semi-analytical ones: the GSM algorithm [3] and Carder algorithm[4].
This work has been supported by MIUR (Ministero dell’Università e della Ricerca), within the framework of IMCA project (Integrated Monitoring of Coastal Areas).
Other poster/slideshow presentations
[Bov.Ka2008] Bovenga F., Conte, D., Nitti, D.O., Nutricato, R., Milillo, G. and Valentino, A., “Preliminary Analysis of Cosmo-SkyMed Interferometric Phase”. 14th Ka and Broadband Communications, Navigation and Earth Observation Conference. September 24-26, 2008. Matera, Italy (2008).
[Gue.FestInnov2008] L. Guerriero, M.T. Chiaradia, R. Matarrese, R. Nutricato, F. Bovenga, A. Morea, D. Conte, F. Intini, K. Tijani, and D.O. Nitti. Nuove potenzialità del telerilevamento satellitare per il monitoraggio ambientale: attività dello spin-off Geophysical Applications Processing - GAP s.r.l. del Politecnico di Bari presso il Dipartimento Interateneo di Fisica. Festival dell'innovazione 2008, Giornata sulla Ricerca nel Settore Aerospaziale in Puglia, Bari, Italy, Dec 4, 2008.
Presso il Dipartimento Interateneo di Fisica dell’Università e del Politecnico di Bari, il Gruppo di Remote Sensing opera da più di dieci anni nel campo dell’elaborazione dei segnali e delle immagini ed ha sviluppato metodologie, modelli numerici ed algoritmi per numerose applicazioni innovative del telerilevamento satellitare, dal monitoraggio del territorio allo studio dell’ambiente e dell’evoluzione climatica. Due sono le aree di specializzazione che caratterizzano le competenze del gruppo e che hanno permesso di creare lo spin-off Geophysical Applications Processing - GAP s.r.l. del Politecnico di Bari. La prima riguarda l’interferometria differenziale con immagini radar ad apertura sintetica (SAR) e le tecniche interferometriche multitemporali con gli scatteratori persistenti in aree di scarsa urbanizzazione. Con questa tecnica è possibile individuare movimenti millimetrici e velocità di spostamento dell’ordine di alcuni millimetri l’anno per strutture antropiche o natuali. Le procedure sviluppate, per le quali è stata avviata la procedura di brevettazione, sono state applicate per l’individuazione di instabilità dei pendii e spostamenti premonitori di pericolo di frana, instabilità di edifici in aree urbane, instabilità di manufatti, quali dighe, viadotti, ponti, etc. Nuove interessanti potenzialità di questa metodologia sono oggi offerte dalla recentissima costellazione di satelliti COSMO-SkyMed dell’Agenzia Spaziale Italiana. La seconda area di specializzazione riguarda il monitoraggio dello stato di salute delle acque costiere e la densità di aerosol nell’atmosfera, utilizzando, mediante sofisticate procedure di filtraggio e di inversione numerica, dati ad alta frequenza temporale e a bassa risoluzione spaziale, forniti dai numerosi sensori multispettrali delle piattaforme spaziali realizzate dall’ESA e dalla NASA per studi di oceanografia. Diversi progetti finanziati dall’Agenzia Spaziale Italiana, dall’Unione Europea, dall’Agenzia Spaziale Europea, dal MIUR, dalla Regione Puglia, quali MORFEO (ASI), IMCA (MIUR), LEWIS (VII Programma Quadro), WETSYS (Interreg Italia-Albania), nonché la recente convenzione tra GAP s.r.l. e la Regione Puglia in materia di incendi boschivi, si sono avvalsi dell’apporto scientifico e dei risultati della ricerca del Dipartimento Interateneo di Fisica. I risultati più maturi sono ora divenuti applicazioni commerciali dello spin-off GAP s.r.l. Verrà presentata una panoramica delle metodologie sviluppate dal Gruppo di Telerilevamento di Bari e da GAP s.r.l., nell’ambito di recenti progetti nazionali ed internazionali.
[Lat.ICT2008] A. Lattanzi, F. Bettarelli, S. Cecchi, R. Nutricato, "hArtes Toolchain: algorithm space exploration and translation toolbox", poster presented at ICT Conference - Lyon (France), 25-27 November 2008.
[Bov.VECIMS2007] F. Bovenga, E. Miali, R. Nutricato, M. T. Chiaradia, “GIS-based system for Landslide Early Warning index measurement”, Proceedings of IEEE International Conference on Virtual Environments, Human-Computer Interfaces, and Measurement Systems (VECIMS 2007), 25-27 June 2007, Ostuni (Italy). DOI: 10.1109/VECIMS.2007.4373932. E-ISBN: 978-1-4244-0820-7. Print ISBN: 978-1-4244-0820-7
Landslides are one of the most serious natural and man induced hazards. The paper presents an innovative system dedicated to the measurement of landslide warning index. The system is based on a Geographic Information System (GIS) inference engine which properly combine satellite Earth Observation (EO) measurements and static geophysical parameters. The system has been developed in the framework of a FP5 European project and it is aimed to provide an operative and flexible tool for public and private entities involved in land management, and in particular in mitigation of both landslide hazard and risk. Particular attention will be devoted to the role that the GIS environment plays as optimal measurement environment since it provides flexible interface between human (both high level geophysical experts and low level end users) and data (heterogeneous data in input to the geophysical model, warning maps in output).
The authors would mention all the partners of LEWIS project and in particular Dr. Janusz Wasowski and Dr. Domenico Casarano from CNR-IRPI, Bari for the work dedicated to define and to validate the geophysical rules and, the staff of SILOGIC for the development of the GIS tool for PS analysis.
[Gue.VECIMS2007] A. Guerriero, R. Matarrese, A. Morea, C. Pasquale, F. Ragni, K. Tijani, "GRID Services for SST Measures". , Proceedings of IEEE International Conference on Virtual Environments, Human-Computer Interfaces, and Measurement Systems (VECIMS 2007), 25-27 June 2007, Ostuni (Italy). DOI: 10.1109/VECIMS.2007.4373935. ISBN: 978-1-4244-0820-7
The effects of the increase in the average temperature of the Earth's near-surface air and oceans in recent decades are dramatically manifest: desertification, glacier retreat, increased intensity and frequency of hurricanes and extreme weather events. Monitoring the ecosystem is currently the only way we have to assist Governments in making sound decisions concerning the reduction of these dramatic effects and the protection of our environment. Satellite remote sensing data, offering the possibility of covering large spatial area with a high temporal frequency, represents the ideal solution to monitoring, but the huge data volume to process, calibrate and validate by in-situ dataset, cannot be operated effectively by traditional database and computational resources. Grid technology, easily providing powerful computational resources and efficient distributed data management, is an excellent solution for remote sensed data processing and management system. In this paper we present a prototype of a Remote Sensed Data processing system on Grid technology that allows, by a graphical interface, data selection and processing to validate SST measure particularly in costal area.
This work was partly supported by European Regional Development Found (ERDF), “New.Ton” Project (project code A.1.180 - Interreg IIIB Archimed programme). The authors thank very much the reviewers for their constructive and useful comments.
[Was.FRINGE2007] J. Wasowski, F. Bovenga, R. Nutricato, D. Conte, A. Refice, Z. Kowalski, M. Graniczny, "Satellite interferometry reveals spatial patterns of subsidence in the ancient Wieliczka Salt Mine (UNESCO Heritage Site, Poland)", Proceedings of FRINGE 2007, ESA-ESRIN, Frascati (RM), Italy, 26-30 Nov. 2007.2. ISBN 9789292912133. ISSN 1609-042X.
We present the first Persistent Scatterers SAR Interferometry (PSI) data on the subsidence phenomena in the town of Wieliczka. The town is home to a unique salt mine, over 700 years old, one of the best known tourist attractions in Poland. Each year the mine is visited by about 1 million tourists from all over the world and in 1978 UNESCO placed it on its first International List of theWorld Cultural and Natural Heritage. There is evidence that the mining legacy has influenced the ground and building stability in the town, which is sited directly above the mine. The application of the PSI SPINUA technique has led to the identification of numerous radar targets (over 100 PS/km2), suitable for ground motion monitoring in the Wieliczka area. The results show the presence of continuous subsidence with average movements ranging from about 1 to 2 cm/yr in the period 1992-2000. The detected subsiding zone corresponds well to the extent of the underground salt mine. There are also indications of possible linkages between the mine-induced subsidence and the presence of the relatively large landslides occurring on the north slopes facing the Wieliczka area.
The ERS images were provided by ESA under the ALOS ADEN 3595 project. JW thanks Marek and Karol Kotlinowski for their hospitality and help, A. Lesniak for precipitation data and A. Trzoslo for sharing information on the Wieliczka mine operations.
[Vie.EnvSymp2007] M. Viel, G. Ceriola, P. Manunta, R. Matarrese, V. De Pasquale, G. Pasquariello, "MARCOAST Adriatic Service, MERIS Products Validation". Proc. 'Envisat Symposium 2007', Montreux, Switzerland 23-27 April 2007. ESA SP-636, ISBN 92-9291-200-1. ISSN 1609-042X.
Coastal zones are the most populated and utilized areas of the earth. Assessment and regular monitoring of coastal waters quality are key activities for a sound management of the coastal areas. Chlorophyll-a (Chl-a) is one of the key parameters used for evaluating coastal water quality status. MarCoast is a three year project funded by the European Space Agency (ESA) with the aim of establishing a durable network of marine and coastal information services from remote sensing data, integrated with in-situ measurement, in close cooperation with national and regional authorities. In MarCoast, Chl-a and Water Transparency parameters are both measured with the MERIS instrument onboard ENVISAT. This paper describes the outcomes of validation activities of the MERIS products and algorithms performed for the Adriatic Sea using in situ data. First validation results made on oneyear dataset were promising. However, further analysis should be made to confirm this first year good results and to improve regionalization of the algorithms.
Work carried out in the framework of MarCoast (Marine and Coastal Environmental Information Services), a 3 years (2005–2008) project fully funded by the European Space Agency (ESA) in the context of the GMES (Global Monitoring for Environment and Security) Service Element Programme.
[Was.EnvSymp2007] J. Wasowski, D. Casarano, C. Lamanna, F. Bovenga, D. Conte, R. Nutricato, A. Refice, P. Berardino, M. Manzo, A. Pepe, G. Zeni, R. Lanari, "A Comparative Analysis of DInSAR results achived by the SBAS and SPINUA techniques: the Maratea Valley case study, Italy", Proceedings of ESA-ENVISAT Symposium 2007, 23-26 April, 2007, Montreux, Swiss. ESA SP-636, ISBN 92-9291-200-1. ISSN 1609-042X.
We compare the results of two independent synthetic aperture radar differential interferometry (DInSAR) ap-proaches to slope instability investigations in the Mara-tea valley (Southern Italy), based on different process-ing methods and software. The area selected for the comparison is well ground truthed and provides suitable examples of movements ranging from mm to cm per year. The DInSAR analyses are based on the Small Baseline Subset (SBAS) and Stable Point INterferome-try over Unurbanised Areas (SPINUA) techniques. Both methods are applied to SAR images acquired by the ERS-1/2 satellites in the period 1992-2000. Despite the differences in the data processing and minor discrepan-cies between the displacement maps, mainly due to dif-ferences in data classification and thresholding, the re-sults obtained from the two techniques are largely com-parable and provide very similar ground surface motion information that leads to a clear distinction between sta-ble and unstable areas and between the zones with dif-ferent velocity of movement.
The European Space Agency provided the ERS SAR data. The authors also thank the Autorità Interregionale di Bacino della Basilicata for the orthophotos of the Maratea Valley.
[Gue.MACMESE2007] A. Guerriero, R. Matarrese, A. Morea, K. Tijani, "A GRID Enabled Look-Up Table for Aerosol Optical Thickness Estimation on Coastal Water". Proceedings of the 9th WSEAS International Conference on Mathematical and Computational Methods in Science and Engineering, pp. 137-141, (MACMESE 07), Trinidad and Tobago, 5-7 November 2007. ISBN: 978-960-6766-12-1
Coastal area represents one of the more delicate and complex relation between natural environment and human activities. Remote sensing, offering considerable understanding of the temporal dynamics of bio-physical factors at different scale, represents a solution for monitoring the ecosystem. In particular marine phenomena, i.e. Sea Surface Temperature, chlorophyll concentration etc. can be related to the sea color observed from satellites. However standard satellite products, such as chlorophyll concentrations maps calculated from MODIS data, are useful only for oceanic water and cannot be directly extended to coastal water. For coastal water quality evaluation, specific inversion procedures should be used. Some of these procedures are based on look-up table generation that are computational intensive. In this paper a Grid based approach is proposed for LUT generation. This approach, producing accurate estimation of Aerosol Optical Thickness, represents a useful system to give fast and accurate answers without demand large economic investments.
This work is partially supported by the "New. Ton." Project, co-financed by the ERDF through the INTERREG IIIB ARCHIMED Programme A.1.180 (http://www.newton.interreg.net)
[Gue.IWASI2007] A. Guerriero, R. Matarrese, A. Morea, C. Pasquale, F. Ragni, K. Tijani, "A Grid Portal to Improve SST Maps". IWASI 2007, Bari June 26-27, 2007. DOI: 10.1109/IWASI.2007.4420044. E-ISBN: 978-1-4244-1245-7. Print ISBN: 978-1-4244-1245-7.
New technologies, sensors and techniques increase every day the human capabilities to monitoring the ecosystem and understanding the anthropogenic influence in its evolution. Particularly remote sensing, offering the possibility of covering large spatial area with a high temporal frequency, represents the ideal solution to environmental monitoring, but at the same time it is a challenge for any conventional computational resource due to the algorithms complexity and to the huge data volume to process. EOS satellites with their Moderate Resolution Imaging Spectroradiometers (MODIS) view the entire Earth's surface every days, acquiring data in 36 spectral bands. These data are used to make several products, i.e. Oceans Sea Surface Temperature Maps, essential for understanding a number of oceanographic and atmospheric phenomena. On coastal areas the SST product is unreliable requiring ad hoc processing and calibration. These requirements fit better on High Performance Computing and Grid technologies that can provide powerful computational resources and efficient distributed data management. Several Grid infrastructures have been proposed in literature for Earth observation projects [1-3], however they report excellent performance but a too complex computing environment for non grid expert users. In this paper we present a Grid Portal for Remote Sensing data processing that allows scientists to access resources, execute and monitor data processing on Grid technology using a simple web browser interface. As an example of services that can be offered in this Portal we implement services for producing calibrate costal area SST maps and for combining these with standard product to obtain improved SST maps.
This work was partly supported by European Regional Development Found (ERDF), “New.Ton” Project (project code A.1.180 - Interreg IIIB Archimed programme). The authors thank very much the reviewers for their constructive and useful comments.
National Conference Proceedings
[Mat.Wetland2007] R. Matarrese, M.T. Chiaradia “Applicazioni Del Telerilevamento A Zone Costiere E Umide”. Atti Del Congresso Environmental Features And Sustainable Development Of The Albanian And Apulian Wetlands – Tirana, 23 Novembre 2007, Pp. 107-110, Edizioni Dal Sud. ISBN: 88-7553-061-0.
[Mat.ChimAmb2007] R. Matarrese, V. De Pasquale, S. Rochira, P. Cosma, M. Trotta, M.T. Chiaradia, G. Pasquariello. “Calibrazione di un profilatore per misure fluorimetriche in situ per lo sviluppo di modelli bioottici satellitari". X Congresso Nazionale Di Chimica Dell'ambiente E Dei Beni Culturali, Acaya, Lecce, 11-15 Giugno 2007.
Le acque costiere rappresentano solo una piccola frazione delle acque naturali del pianeta, ma risultano di fondamentale importanza per il loro ruolo economico, sociale ed ecologico. Il loro monitoraggio assume, dunque, una particolare rilevanza. La misura di parametri fisici, chimici e biologici che fungono da indicatori della qualità delle acque è effettuata tradizionalmente con campagne periodiche di prelievo di campioni a mare. I recenti sviluppi dei sistemi di elaborazione dati di immagini satellitari, hanno mostrato come questa nuova tecnica possa integrarsi a quelle tradizionali, fornendo informazioni sinottiche e a basso costo di alcuni indici dello stato delle acque. Da misure satellitari sono determinabili solo quelle sostanze che interagiscono con la radiazione solare che ha attraversato la superficie marina, ovvero la clorofilla di alghe e cianobatteri, i sedimenti sospesi e la sostanza gialla. Gli algoritmi ad oggi disponibili sono ottimizzati per misure in acque oceaniche (Caso I). Per le aree costiere (Caso II), tuttavia, tali algoritmi possono non essere adeguati ed è quindi necessario svilupparne una versione che sia adatta alle caratteristiche di queste acque, che possono variare drasticamente da zona a zona. Tale sviluppo può essere effettuato solo utilizzando misure chimiche, biochimiche e radiometriche in situ. Il contenuto in clorofilla di un'acqua è direttamente legato alla quantità di microrganismi fotosintetici ivi contenuti. La loro distribuzione in termini di specie e di concentrazione è fortemente dipendente dalle caratteristiche chimico fisiche delle acque, come ad esempio temperatura, pH e soprattutto concentrazione di nutriliti. Questi parametri dipendono dalla zona costiera dalla quale i prelievi sono effettuati e tendono ad essere differenti fra i siti di Taranto, Margherita di Savoia e Isole Tremiti oggetto dell’indagine. Le misure in situ del contenuto in clorofilla parametro su cui si focalizza questo lavoro, sono effettuate tramite misure fluorimetriche. Campioni di acqua prelevati nelle posizioni delle misure, sono successivamente analizzati in laboratorio con cromatografia liquida. Le misure fluorimetriche sono così calibrate con i valori ottenuti in laboratorio e vengono a loro volta utilizzate per calibrare gli algoritmi satellitari. In questo lavoro verranno presentate misure fluorimetriche e radiometriche, ottenute con un profilatore della Satlantic Inc., che rappresentano i valori di riflettanza superficiale dell’acqua corretti atmosfericamente da satellite. Saranno inoltre presentate le calibrazioni del profilatore ottenute con le alghe Clorella, Laminaria, Fucus vesciculus ed il cianobatterio Spirulina e la correlazione di questi dati con le misure di fluorescenza in situ.
[Nit.EGU2007] D. O. Nitti, F. Bovenga, A. Ganas, R. Nutricato, A. Refice, and M.T. Chiaradia. Refined fault model for the Mw=6.3, June 15, 1995 Aigion EQ (Greece) derived from InSAR data and implications for extensional tectonics of the western Corinth rift. Geophysical Research Abstracts, 9:04866, 2007. SRef-ID: 1607-7962/gra/EGU2007-A-04866. eISSN: 1607-7962.
On June 15th, 1995, a Mw= 6.3 earthquake struck the western part of the Gulf of Corinth with mainshock epicentre 16 km NNE from Aigion city. The present study presents the application of SAR interferometry (InSAR) techniques for obtaining the co-seismic deformation pattern and inferring the fault model parameters for this seismic event. A second objective is test the Rigo et al., (1996) model for active tectonics of the western Gulf. Both ascending (Track 279, Frame 2835) and descending (Track 415, Frame 765) ERS-1/2 SAR acquisitions were initially selected within 2 years from the mainshock, with the aim of investigating the area affected by the earthquake under different observation directions, different atmospheric conditions and during different seismic activity phases. Standard DInSAR processing was performed in order to produce a stack of differential interferograms. A SRTM DEM of the area was used to remove the topographic component from the interferometric phase. The data time distribution appears suitable for investigating possible pre- and post-seismic activity; however, both pre-shock and after-shock interferograms do not show evidence of any deformation pattern, as the dominant differential phase component seems principally due to atmospheric signal. An in-depth investigation of the co-seismic activity has been instead possible thanks to several suitable interferograms obtained by using both descending and ascending data. In both cases a co-seismic deformation pattern is clearly visible around Cape Psaromita. The spatial distribution of fringes seems in good agreement with that reported in the study of Bernard et al., 1997. However, atmospheric artefacts are recognizable, especially for daytime acquisitions. Therefore, a stacking procedure has been performed in order to filter out the atmospheric signal and to obtain a more reliable deformation pattern. Six complex descending differential interferograms were selected, generated from seven acquisitions acquired between 19 August 1993 and 23 June 1996. After phase offsets correction, a weighted average of the unwrapped interferograms was performed. The resulting differential interferogram contains mainly the temporally correlated displacement signal, while the temporally uncorrelated atmospheric components have been mostly filtered out. By using this refined interferometric pattern of the deformation field, measured along the Line Of Sight (LOS) of the ERS spacecrafts, forward and inversion procedures were performed in order to obtain a new reliable fault model for the Aigion EQ. This single fault plane solution represents a significant improvement of the Okada-like fault models proposed in Bernard et al., (1997), because the effect of the crustal layering of the western Gulf of Corinth was included in the fault model formulation and because of the smaller RMSe between measured and synthetic deformation pattern. Our main findings include: a) the 1995 earthquake did not occur along the onshore Aigion Fault b) the 1995 earthquake occurred along a low angle fault probably with increasing dip towards the surface c) the 1995 earthquake did not rupture the surface and d) the high-angle, antithetic faults of McNeil et al., (2005) terminate against the low angle fault.
[Kot.ApplOpt2006] S. Y. Kotchenova, E. F. Vermote, R. Matarrese, F. J. Klemm, Jr., "Validation of a New Vector Version of the 6S Radiative Transfer Code for Atmospheric Correction of MODIS Data (Part I)". Applied Optics, Vol. 45, Issue 26, pp. 6762-6774 (2006). DOI: 10.1364/AO.45.006762. ISSN: 1559-128X. eISSN: 2155-3165.
A vector version of the 6S (Second Simulation of a Satellite Signal in the Solar Spectrum) radiative transfer code (6SV1), which enables accounting for radiation polarization, has been developed and validated against a Monte Carlo code, Coulson’s tabulated values, and MOBY (Marine Optical Buoy System) water-leaving reflectance measurements. The developed code was also tested against the scalar codes SHARM, DISORT, and MODTRAN to evaluate its performance in scalar mode and the influence of polarization. The obtained results have shown a good agreement of 0.7% in comparison with the Monte Carlo code, 0.2% for Coulson’s tabulated values, and 0.001–0.002 for the 400–550 nm region for the MOBY reflectances. Ignoring the effects of polarization led to large errors in calculated top-of-atmosphere reflectances: more than 10% for a molecular atmosphere and up to 5% for an aerosol atmosphere. This new version of 6S is intended to replace the previous scalar version used for calculation of lookup tables in the MODIS (Moderate Resolution Imaging Spectroradiometer) atmospheric correction algorithm. (c) 2006 Optical Society of America
We thank F.-M. Breon for providing the Monte Carlo code, A. Lyapustin for providing SHARM, G. Anderson for providing MODTRAN, D. Clark for providing the MOBY measurements, F.-M. Breon and A. Lyapustin for multiple discussions and suggestions during this study, and the three anonymous referees for their helpful comments. This work was supported by NASA contract NNG04HZ17C.
[Bov.EnGeo2006] F. Bovenga, R. Nutricato, A. Refice, J. Wasowski, "Application of Multi-temporal Differential Interferometry to Slope Instability Detection in Urban/Peri-urban Areas''. Engineering Geology (2006). Volume: 88, Issue: 3-4, Pages: 218-239. DOI: 10.1016/j.enggeo.2006.09.015. ISSN: 00137952.
We present two case studies regarding the application of Synthetic Aperture Radar (SAR) Persistent Scatterers Interferometry (PSI) techniques to landslide-prone slopes situated in the municipal territories of Caramanico Terme and Volturino (Italy). The analysis of satellite SAR data with PSI techniques poses often problems on sites where, due to the scarcity of human artefacts and the presence of vegetation cover, density of coherent points (PS) is low (b10 per km2). Moreover, the steep and rough topography typical of landslide-prone areas hamper the interferometric pre-processing, making more difficult the joint estimation of displacements and of DEM errors. Under these conditions the significance of temporal interferometric phase trends can be uncertain and conservative assumptions, necessary to ensure low false detection probabilities, need to be coupled with innovative processing strategies to increase the detection efficiency of PS objects. Here, the SPINUA (Stable Point Interferometry over Un-urbanised Areas) processing technique is applied together with an alternative PS Candidate (PSC) selection procedure based on the use of pixels classified as urban. The cases of Caramanico and Volturino are representative, respectively, of harsh and favourable conditions for PSI applications. The results from Caramanico show clusters of PS exhibiting similar line-of-sight (LOS) deformation behaviour in the period 1995–2000. The locations ofmoving PS often coincidewith distressed buildings and appear consistent with the areal distribution of recent and past landslide activity. The temporal displacement trends, however, are characterised by very low annual average velocities (from 3 to 7 mm/y) and it is uncertain to what extent the PS data reflect true slope movements, local deformations (e.g. settlement of engineering structures) or both. Thanks to the more favourable conditions, the application of the standard SPINUA approach in the Volturino area was sufficient to obtain suitable densities of PS, as well as spatially and temporally consistent displacement results for a period 1992–2000. In particular, a group of moving PS was identified in a peri-urban area, known for the past and recent slope stability problems. The slowly moving PS (from 3 to 5 mm/y) fall in a location that, unlike the remaining part of the town, is characterised by the presence of many distressed buildings and structures. Although the site information confirms the reliability of PS data, in the absence of ground monitoring and detailed records of landslide movements, it is difficult to identify the main mechanism of the detected deformations. In general, in geologically and topographically complex urban/peri-urban settings, the significance of very low-velocity PSI surface displacements should always be considered together with in situ geotechnical controls and ground monitoring data.
This work was supported in part by the European Community (Contract No. EVGI 2001-00055- Project LEWIS) and by the Italian Space Agency (ASI) projects (Contracts No. I/R/27/00 and I/R/073/01). The SPINUA algorithm was developed and tested in the framework of the above-mentioned projects. The ERS images were provided by the European Space Agency under ENVISATAO- 313 and CAT-1 Id:2653 projects.We also thank the administrations of Regione Abruzzo, Caramanico and Volturino Municipalities for their support. Continuous support and numerous discussions with Prof. Luciano Guerriero are gratefully acknowledged. The authors acknowledge the POLIMI group, and in particular Carlo Colesanti and Alessandro Ferretti, for helpful discussions on the Permanent Scatterers. Finally, we thank Paolo Farina,VincenzoDel Gaudio and an anonymous reviewer for their helpful comments.
[Ref.TGRS2006] A. Refice, F. Bovenga, R. Nutricato, "MST-based stepwise connection strategies for multi-pass radar data, with application to co-registration and equalization". IEEE Transactions on Geoscience and Remote Sensing (2006). Volume: 44, Issue: 8, Pages: 2029-2040. ISSN: 01962892. DOI: 10.1109/TGRS.2006.872907.
This paper proposes a unified framework for predicting optimized pairing strategies for interferometric processing of multipass synthetic aperture radar data. The approach consists in a minimum spanning tree (MST) structure based on a distance function encoding an a priori model for the interferometric quality of each image pair. Using a distance function modeled after the interferometric coherence allows reproducing many “small baseline” strategies presented in the recent literature. A novel application of the method to the processing steps of image coregistration and equalization is illustrated, using a test European Remote Sensing Satellite dataset.Widespread methods used for these two operations rely on the computation of the amplitude cross correlation over a large number of corresponding tie patches distributed over the scene. Geometric shift and radiometric equalization parameters are estimated over the patches and used, respectively, within a polynomial warp model and a radiometric correction scheme. The number of reliable patches available behaves similarly to the interferometric synthetic aperture radar (InSAR) coherence with respect to the baselines, and can be assimilated to a quality figure for the derivation of theMST. Results show an improvement in the quality of the stepwise (SW)-processed image stack with respect to the classical single-master procedure, confirming that the SW approach is able to provide better conditions for the estimation of correlation-related InSAR parameters.
The authors thank L. Guerriero (Politecnico di Bari, Italy) for the many ideas and discussions about the subject of this paper. J. Wasowski (CNR-IRPI) and A. Blonda (CNR-ISSIA) are acknowledged for kind permission of using the data, obtained through the ENVISAT and ERS ESA-AO projects. Finally, the authors would like to thank the anonymous reviewers whose insightful observations and suggestions greatly helped to improve the quality of the paper.
International Conference Proceedings
[Nit.IGARSS2006] D. O. Nitti, F. Bovenga, R. Nutricato, A. Refice, and M.T. Chiaradia. InSAR derived deformation patterns related to the Aigion earthquake (Greece). In Proceedings of International Geoscience and Remote Sensing Symposium, Denver, Colorado, USA, Jul. 31-Aug. 4, 2006. DOI: 10.1109/IGARSS.2006.403. ISSN: 2153-6996. Print ISBN: 0-7803-9510-7. Scopus: 2-s2.0-34948841382. WOS:000260989400398
The detectability of the deformation pattern produced by the June 15, 1995 Aigion Earthquake with DInSAR techniques is ensured by its magnitude (MW = 6.3), shallow depth and dip-slip mechanism. In this paper, stacking procedures are applied to a series of ERS interferograms in order to filter out from the differential phase field the atmospheric signal, and an a posteriori test is used to check the statistical properties of the atmospheric signal both in time and space. Based on the DInSARderived deformation pattern, a new fault model is proposed that takes into account the crustal layering of the western part of the Gulf of Corinth.
The authors thank Dr. Athanassios Ganas from the National Observatory of Athens for the helpful technical hints. This work was supported in part by the European Community (Contract EVGI 200-00055 - Project LEWIS). Data provided by European Space Agency under the CAT-1 project n. 2653.
National Conference Proceedings
[Nit.GOLD2006] D. O. Nitti, F. Bovenga, R. Nutricato, A. Refice, and M.T. Chiaradia. Refined InSAR derived fault model for the Mw=6.3, June 15, 1995 Aigion EQ (Greece). In Proceedings of IEEE GOLD Remote Sensing Conference, Bari, Italy, December 4-5, 2006. ISBN 978-889591118-2.
The detectability of the deformation pattern produced by the June 15, 1995 Aigion Earthquake with DInSAR techniques is ensured by its magnitude (MW = 6.3), shallow depth and dip-slip mechanism. In this paper, stacking procedures are applied to a series of ERS interferograms in order to filter out from the differential phase field the atmospheric signal, and an a posteriori test is used to check the statistical properties of the atmospheric signal both in time and space. Based on the DInSARderived deformation pattern, a new fault model is proposed that takes into account the crustal layering of the western part of the Gulf of Corinth.
The authors thank Dr. Athanassios Ganas from the National Observatory of Athens for the helpful technical hints. This work was supported in part by the European Community (Contract EVGI 200-00055 - Project LEWIS). Data provided by European Space Agency under the CAT-1 project n. 2653.
[Mat.GOLD2006] R. Matarrese, M. Acquaro, A. Morea, K. Tijani, M.T. Chiaradia, "Applications Of Remote Sensing Techniques For Mapping Posidonia Meadows". In Proceedings of IEEE GOLD Remote Sensing Conference, Bari, Italy, December 4-5, 2006. ISBN 978-889591118-2.
Monitoring marine benthic communities is generally considered to be an essential activity to increase understanding and hence the correct management of coastal areas. Seagrass ecosystems protect shorelines against erosion and are efficient in removing nutrients from marine waters and surface sediments. Therefore they are an important element in improving the water quality of coastal waters. Remote sensing techniques offer one solution to the problem of surveying the extent and development of benthic communities by offering synoptic information over large spatial scales. A large variety of approaches may be used to map seagrasses. The selection of sensor imagery and of a classification method is related to the features of investigated area, the lower limit of the communities (maximal depth), the degree of precision required and the cost-effectiveness in relation to time spent, [1]. In this study, thematic maps of sea bottom habitats are produced from different remote sensing sensors' data (Landsat ETM+, ASTER), and with a Maximum Likelihood classification method. A comparison with ground truth measurements in the Ionian Sea shows the advantages and the limits of each approach, according to a reliability scale suggested by Pasqualini V. et al. in 1997 [2].
This research is carried out by Physics Dept.-Politecnico of Bari in the framework of IMCA project in Puglia, Italy, supported by MIUR with the collaboration of the Biologic Dept. of University of Bari.
Conference Abstracts
[Gan.HAZARDS2006] A. Ganas, D.O. Nitti, F. Bovenga, R. Nutricato, A. Refice and G. Papadopoulos. “Improved fault model of the 1995 Aigion earthquake retrieved from ERS InSAR data.” 11th International Symposium on Natural and Human Induced Hazards and 2nd Workshop on Earthquake Prediction Abstract Volume, June 22-25, 2006, Patras, Greece, pag.40.
This work aims at the application of SAR interferometry (InSAR) techniques for obtaining the co-seismic deformation pattern of the June 15, 1995 M=6.2 earthquake and inferring the fault model parameters for this seismic event. InSAR thanks to its large-area coverage of the deformation field provides useful measurements for damage assessment of seismic events and fault modelling. Standard InSAR processing was performed through the DORIS software in order to produce a stack of differential interferograms. A void-filled, SRTM-derived DEM was used to remove the topographic component from the interferometric phase. A new Okada-like fault solution is proposed, which is derived by inverting displacement obtained through InSAR stacking procedures, as well as the present knowledge on the crustal layering in the western Gulf of Corinth. In addition, the r.m.s. computed on the difference between the refined deformation pattern and the synthetic deformation pattern obtained according to the new parameters is better than that reported in previous studies. The solution includes the most critical focal parameters such as fault strike (277), dip direction (N7E), dip angle (31), Centroid depth (7.6 km), and seismic moment. Further refinements could be obtained by assuming a more complicated fault model consisting of many planes with different geometries. The implications for extensional tectonics of the western Gulf of Corinth are also discussed.
[Gue.EGU2006] L. Guerriero, F. Bovenga, R. Nutricato, J. Wasowski, D. Casarano, P. Gostelow, V. Del Gaudio, P. Blonda, A. Refice, "Developing a Landslide Early-Warning System based on satellite measurements", Geophysical Research Abstracts, Vol. 8, 07362, 2005 SRef-ID: 1607-7962/gra/EGU06-A-07362, European Geosciences Union 2006, Wien, Austria, 02-07 April 2006. eISSN: 1607-7962.
This contribution presents some results of LEWIS (Landslide Early Warning Integrated System) project supported by the European Commission and concluded in 2005. The prime objective of the proposed research was to develop an approach which increases and promotes the value of comparatively low-cost, wide-area satellite data as an input to the assessment of hazard and risk from ground movements. The key element in the LEWIS project is to avoid trying to infer absolute values of relevant geophysical parameters from Earth Observation (EO) data, but only their changes in time in the wider sense of “deviations from a known temporal evolution model”. Other periodic information can be obtained from existing ground networks, e.g. for rain and earthquakes. The detected changes have to be integrated into a Geographic Information System (GIS), together with other more static parameters, and used to infer potential slope stability changes and to produce early warning. The output product of the LEWIS project can be defined as an updateable slope instability susceptibility map, based on changes detected from moderate resolution EO data.The approach has been based on the well known principle that either an increase of shear stresses and/or the decrease of effective material shear strengths over a period of time are the primary cause of increasing susceptibilities to slope instability, thus contributing to first-time failures or reactivated movements on pre-existing slip surfaces. The complementary expertise of the geologic and the Earth observation components of the project team allowed to define a geotechnical model suitable for the spatial/ temporal resolution and for the precision of the EO change measurements. The geotechnical inference model firstly uses GIS topographic and geological ground data (a slope map derived from a Digital Elevation Model, a previous landslide map, a description of the lithological classification distinguishing between soil and rocks, and a brittleness index, reflecting the stress-strain behaviour of the engineering soils) to identify potential levels of susceptibility to deformation in slopes which are close to a factor of safety of 1.0, i.e. they are susceptible to mass movement. Secondly it integrates land use change maps derived by EO data to show levels of warning with respect to that deformation. The methodology used for the production of the land use change maps is based on advanced artificial intelligence techniques, i.e. neural networks classifiers and fuzzy logic and it follows three different approaches to change detection: a supervised approach, an unsupervised approach and a hybrid approach. SAR Interferometry techniques based on Persistent Scatterers (PS) approach are used to give a warning signal through the detection of precursory movements, which may give rise to conditions leading to landslides, since the PS-detected slow ground deformations can indicate ongoing ground instability. After in situ validation the PS data indicative of movements at an average velocity equal or greater than 3 mm/year, can be added to the change-based model output in the warning map as a direct indicator of potential instability. The stable PS can also be taken into account and interpreted as signals that strongly indicate areas of ground stability. The final result of the LEWIS project is a working prototype of a landslide early warning system, designed to cover regional areas. The prototype has been validated with encouraging results on two Italian test sites originally selected for the experiment. The verification of the approach on a third test site, in Greece, is still under way.
This work was supported in part by the European Community (Contract No. EVGI 2001-00055 - Project LEWIS).
[Was.EGU2006] J. Wasowski, F. Bovenga, D. Casarano, R. Nutricato, A. Refice, "Tracking And Interpreting Ground Surface Deformations Detected With PSI Techniques in Landslide-Prone Hilltop Towns: Case Study From Italy", Geophysical Research Abstracts, Vol. 8, 05911, 2005 SRef-ID: 1607-7962/gra/EGU06-A-05911, European Geosciences Union 2006, Wien, Austria, 02-07 April 2006. eISSN: 1607-7962.
By applying the Persistent Scatterers Interferometry (PSI) techniques to the currently available satellite radar imagery, it possible to detect and monitor very slow displacements (from millimetres to centimetres per year), occurring on selected point targets (PS) exhibiting coherent radar backscattering properties (mainly buildings and other man-made structures). In this study we focus on some difficulties in interpreting the exact geological/geotechnical origin of the PSI results obtained by applying the SPINUA algorithm to ERS1and2 radar data. The work, conducted in the framework of the EU project LEWIS, regards the Daunia region (Southern Apennines), which includes several isolated small hilltop towns affected by slope instability problems. Examples from Daunia urban/peri-urban areas are used to illustrate that, when very slowly moving PS are detected on hillslope areas, this does not necessarily mean that their motions represent slow landslide movements. In general, on slopes, surface displacements over time might be found to be in a downslope direction but such deformations might not necessarily always reflect shear movements or movements leading to shear failure, i.e. to landsliding. The interpretation of PS displacement data on urbanised hillslopes is further complicated, because their movements may arise from a variety of natural or anthropogenic processes and thus may reflect complex deformation mechanisms. Indeed, with the exception of “natural” PS (e.g. corresponding to rock outcrop target), without an appropriate in situ investigation, several different interpretations of the very slow PS displacements are possible: i) deterioration of manmade structures, ii) settlement of engineering structures, iii) volumetric strains within soils, iv) natural or anthropogenic subsidence or uplift, v) extremely slow slope deformations that may or may not lead to failure. The recent PS results showing ground surface deformation changes over time on landslide susceptible slopes are very promising, but the geotechnical parameter and geological boundary uncertainties which control them need to be investigated and better understood before they can be confidently used directly for landslide hazard/risk zonation or for predicting (warning) of potential instabilities. Further research is certainly needed using the technique on test areas with different geological and geomorphological scenarios and giving more attention to the structural behaviour of man-made objects that act as PS targets.
This work was supported in part by the European Community (Contract No. EVGI 2001-00055 - Project LEWIS). Images were provided by ESA under the CAT-1 project number 2653, “Advanced SAR Interferometry techniques for landslide warning management”.
J. WASOWSKI, F. BOVENGA, D. CASARANO, R. NUTRICATO, A. REFICE, "Application of PSI techniques to landslide investigations in the Caramanico area (Italy): lessons learnt", Proc. of FRINGE 2005, November 28 - December 1, 2005, Frascati, Italia.
F. BOVENGA, M. T. CHIARADIA, R. NUTRICATO, A. REFICE, J. WASOWSKI, "Application of PSI techniques to slope instability detection in the Daunia mountains, Italy", Proc. of FRINGE 2005, November 28 - December 1, 2005, Frascati, Italia.
A. REFICE, F. BOVENGA, R. NUTRICATO, M. T. CHIARADIA, J. WASOWSKI, "Land-cover classification-based Persistent Scatterers identification for peri-urban applications" , IEEE IGARSS 2005, Proc. of IGARSS 2005, July 25-29 2005, Seoul, Korea.
L. GUERRIERO, F. BOVENGA, R. NUTRICATO, A. REFICE, J. WASOWSKI, "The role of PS Interferometry in the Landslide Early Warning Integrated System (LEWIS) Project.", Proceedings Workshop di Telerilevamento e dissesto idrogeologico, 7-8 July 2005, Cagliari - Italy.
L. GUERRIERO, F. BOVENGA, R. NUTRICATO, A. REFICE, J. WASOWSKI, V. DEL GAUDIO, P. MANUNTA, "Il Progetto LEWIS ed il ruolo della tecnica dei Riflettori Permanenti nel monitoraggio dei pendii instabili", Rivista Italiana di Agrometeorologia anno 9 n.1 Febbraio 2005 - Atti del Convegno AIAM 2005, Agrometeorologia, risorse natuali e sistemi di gestione del teritorio, 3-5 maggio 2005 Caramanico-Vasto, Italia. (Rivista Nazionale)
F. BOVENGA, V. SINGHROY, J. WASOWSKI, "Exploting different radar sensors and InSAR techniques for slope instability monitoring", Geophysical Research Abstracts, Vol. 7, 10892, 2005 SRef-ID: 1607-7962/gra/EGU05-A-10892 European Geosciences Union 2005, Wien, Austria, 24-29 April 2005.
J. WASOWSKI, M. SORGENTE, M. SAVIO, G. LOLLINO, F. GODONE, V. DEL GAUDIO, F. BOVENGA, M. BALDO, "Detection of premonitory slow ground deformations on landslide-prone slopes through GPS and DInSAR techniques: a case study from Italy", Geophysical Research Abstracts, Vol. 7, 07454, 2005 SRef-ID: 1607-7962/gra/EGU05-A-07454 European Geosciences Union 2005, Wien, Austria, 24-29 April 2005.
A. REFICE, F. BOVENGA, R. NUTRICATO, M. T. CHIARADIA, "Assessment of Multitemporal DInSAR Stepwise Processing", IEEE IGARSS 2004, Proc. of IGARSS 2004, September 20-24 2004, Anchorage, Alaska.
F. BOVENGA, A. REFICE, R. NUTRICATO, L. GUERRIERO, M. T. CHIARADIA, "SPINUA: a flexible processing chain for ERS / ENVISAT long term interferometry", Proceedings of ESA-ENVISAT Symposium 2004, 6-10 September, 2004, Saltzburg, Austria.
N. VENEZIANI, V. M. GIACOVAZZO, F. BOVENGA, "Height Retrieval by Using a Pseudo-Differential Approach in SAR Interferometry: Preliminary Results", IEEE IGARSS 2004, Proc. of IGARSS 2004, September 20-24 2004, Anchorage, Alaska.
F. BOVENGA, R. NUTRICATO, A. REFICE, J. WASOWSKI, "Application of Multitemporal Differential Interferometry to Landslide Investigations in peri-urban areas" , Geophysical Research Abstracts of European Geoscience Union I General Assembly, Nice, France, 25-30 April 2004.
J. WASOWSKI, F. BOVENGA, R. NUTRICATO, A. REFICE, D. CASARANO, "Test of Applicability of Multitemporal Differential Interferometry Analysis to Landslide Investigations in Peri-Urban Areas", Proceedings of FRINGE'03, ESA-ESRIN, Frascati, Italy, 1-5 December, 2003.
A. REFICE, F. BOVENGA, R. NUTRICATO, "Stepwise Approach to InSAR Processing of Multitemporal Datasets", Proceedings of FRINGE'03, ESA-ESRIN, Frascati, Italy, 1-5 December, 2003.
F. BOVENGA, S. STRAMAGLIA, R. NUTRICATO, A. REFICE, "Discrimination of different sources of signals in Permanent Scatterers technique by means of Independent Component Analysis", IEEE IGARSS 2003, Proc. of IGARSS 2003, July 21-25 2003, Toulouse, France.
N. VENEZIANI, F. BOVENGA, A. REFICE, "A Wide-Band approach to Absolute Phase Retrieval in SAR interferometry", Multidimensional Systems and Signal Processing, MULT Vol 14 Nos 1-2, Kluwer Academic Publishers, Netherlands 2003.
F. MATTIA, A. M. GATTI, G. PASQUARIELLO, G. SATALINO, F. POSA, A. D'ALESSIO, C. NOTARNICOLA, M. RINALDI, T. LE TOAN, G. PICARD, "Preparing ENVISAT campaign: radar and ground measurements on wheat fields over the Matera test site " in Rivista Italiana di TELERILEVAMENTO, 26,27,28 , 77-82 (2003).
F. BOVENGA, A. REFICE, S. STRAMAGLIA, D. CONTE, "Phase unwrapping by means of scaling information and global optimization algorithms". Proceedings of the SPIE International Society for Optical Engineering 4883, 162-170 (2003).
F. BOVENGA, A. REFICE, R. NUTRICATO, G. PASQUARIELLO, G. DE CAROLIS, "Automated Calibration of Multi-Temporal ERS SAR Data", IEEE IGARSS 2002, Proc. of IGARSS 2002, June 24-28 2002, Toronto, Canada.
R. NUTRICATO, F. BOVENGA, A. REFICE, "Optimum Interpolation and Resampling for PSC Identification", IEEE IGARSS 2002, Proc. of IGARSS 2002, June 24-28 2002, Toronto, Canada.
J. WASOWSKI, A. REFICE, F. BOVENGA, R. NUTRICATO, "On the Applicability of SAR Interferometry Techniques to the Detection of Slope Deformations", Proceedings of 9th IAEG Congress, Durban, South Africa, 16-20 September 2002.
A. REFICE, F. BOVENGA, S. STRAMAGLIA, D. CONTE, "Use of scaling information for stochastic atmospheric absolute phase screen retrieval", IEEE IGARSS 2002, Proc. of IGARSS 2002, June 24-28 2002, Toronto, Canada.
F. BOVENGA, A. REFICE, S. STRAMAGLIA, D. CONTE, "Phase Unwrapping by means of scaling information and global optimization algorithms", Proc. of 9th International Symposium on Remote Sensing, 22-27 Septeber 2002 Aghia Pelagia, Crete, Grecia.
A. REFICE, F. BOVENGA, J. WASOWSKI, L. GUERRIERO, "Use of InSAR Data for Landslide Monitoring: A Case Study from Southern Italy". IEEE IGARSS 2001, Proc. of IGARSS 2001, 09-13 July 2001, Sydney, Australia.
A. REFICE, F. BOVENGA, R. NUTRICATO, J. WASOWSKI, P. BLONDA, G. SATALINO, "Unstable slopes monitoring by Remote Sensing", presented at the NATIONAL WORKSHOP "Getting ready for ENVISAT", 30-31 Maggio e 1 Giugno 2001 - Matera, Centro di Geodesia Spaziale.
A. REFICE, F. BOVENGA, J. WASOWSKI, "Monitoring landslide activity in a peri-urban area by SAR Interferometry". Geophysical Research Abstracts of European Geophysical Society XXVI General Assembly, Nice, France, 25-30 March 2001, Vol. 3.
L. GUERRIERO, A. REFICE, S. STRAMAGLIA, G. SATALINO, N. VENEZIANI, P. BLONDA, M. T. CHIARADIA, "Global Approaches and Local Strategies for Phase Unwrapping". Il Nuovo Cimento, Vol. 24, N.1, Jan. 2001, pp. 11-23.
N. VENEZIANI, F. BOVENGA, F. LOVERGINE, A. REFICE, "Resolution of height ambiguities in DEMs obtained from SAR Interferometry". Proc. of Int. Workshop on Geo-Spatial Knowledge Processing for Natural Resource Management, June 28-29, 2001, Varese, Italy.
A. REFICE, F. BOVENGA, J. WASOWSKI, L. GUERRIERO, N. VENEZIANI, S. ATZORI, A. R. FERRARI, M. MARSELLA, "Detecting Landslide Landslide Activity by SAR Interferometry". Proc. of ERS-ENVISAT Symposium, 16-20 October 2000, Gothenburg, Sweden.
A. REFICE, F. BOVENGA, J. WASOWSKI, L. GUERRIERO, "Using InSAR Data for Landslide Monitoring: a Case Study from Southern Italy". IEEE IGARSS 2000, Proc. of IGARSS 2000, 24-28 july 2000, Honolulu, Hawaii USA.
N. VENEZIANI, F. BOVENGA, F. LOVERGINE, A. REFICE, "A Frequency-domain differential approach to the absolute phase retrieval in SAR interferometry". IEEE IGARSS 2000 , Proc. of IGARSS 2000, 24-28 july 2000, Honolulu, Hawaii USA.
A. REFICE, F. BOVENGA, "Landslide Studies by SAR Differential Interferometry: a Case Study in Southern Italy". Geophysical Research Abstracts of European Geophysical Society XXV General Assembly, Nice, France, 25-29 April 2000.
P. BLONDA, G. SATALINO, A. BARALDI, F. BOVENGA, A. REFICE, "Multitemporal SAR Intensity and Interferometric coherence data fusion". Proc. of III Fusion of Earth Data Symposium, Sophia Antipolis, 26-28 Gennaio 2000.
S. STRAMAGLIA, A. REFICE, L. GUERRIERO, "Statistical mechanics approach to the phase unwrapping problem". Physica A vol. 276, n. 3-4. Feb. 2000, pp. 521-534
G. NICO, M. PAPPALEPORE, G. PASQUARIELLO, A. REFICE, S. SAMARELLI, "Comparison of SAR amplitude vs. coherence flood detection methods - A GIS application". International Journal of Remote Sensing 21(8): 1619-1631, 2000.
S. STRAMAGLIA, L. GUERRIERO, G. PASQUARIELLO, N. VENEZIANI, "Mean Field Annealing for phase unwrapping". Applied Optics, N. 38, pp. 1377-1383, March 1999.
A. REFICE, G. SATALINO, S. STRAMAGLIA, M. T. CHIARADIA, N. VENEZIANI, "Weights determination for minimum cost flow InSAR phase unwrapping". IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293), 1999, pt. 2, p 1342-4 vol.2.
S. STRAMAGLIA, G. NICO, F. LOVERGINE, L. GUERRIERO, "InSAR phase unwrapping algorithm based on mean-field theory". IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293), 1999, pt. 2, p 1345-7 vol.2
L. GUERRIERO, G. NICO, G. PASQUARIELLO, S. STRAMAGLIA, "A new regularization scheme for phase unwrapping". Applied Optics, 37(14), 3053-3058, (1998) tar file (including figures)
M. T. CHIARADIA, L. GUERRIERO, A. REFICE, G. PASQUARIELLO, G. SATALINO, S. STRAMAGLIA, "Phase unwrapping as an ill-posed problem: performance comparison between a neural network based approach and a stochastic search method". Proceedings of the SPIE - The International Society for Optical Engineering, v 3455, p 2-11, 1998.
A. REFICE, M. T. CHIARADIA, L. GUERRIERO, G. NICO, P. N. BLONDA, G. PASQUARIELLO, G. SATALINO, S. STRAMAGLIA, N. VENEZIANI, "Local and global strategies for InSAR phase unwrapping". Proceedings of the SPIE - The International Society for Optical Engineering, v 3497, p 134-45,1998.
S. STRAMAGLIA, G. PASQUARIELLO, L. GUERRIERO, A. DISTANTE, "Interferometric SAR phase unwrapping by parallel tempering on a APE100/Quadrics", LECTURE NOTES IN COMPUTER SCIENCE, Volume: 1401, Pages: 898-900, 1998.
S. STRAMAGLIA, G. PASQUARIELLO, L. GUERRIERO, A. DISTANTE, "Interferometric SAR phase unwrapping by parallel tempering on a APE100/Quadrics supercomputer". High-Performance Computing and Networking. International Conference and Exhibition. Proceedings, 1998, p 898-900.
A. REFICE, G. SATALINO, "Assessment of a neural network approach to the phase unwrapping problem for the SAR interferometry", ERUDIT - European Symposium on Intelligent Techniques, Bari, Italy, 20-21 March 1997, pp. 157-160.
S. STRAMAGLIA, G. NICO, G. PASQUARIELLO, L. GUERRIERO, "Phase unwrapping method based on stochastic relaxation", Proceedings on Aerospace and Remote Sensing , London, 22-26 September 1997, vol. 3217. Postscript file (including figures)
S. STRAMAGLIA, G. NICO, G. PASQUARIELLO, L. GUERRIERO, "Phase unwrapping method based on stochastic relaxation". Proceedings of the SPIE - The International Society for Optical Engineering, v 3217, 1997, p 4-12
A. REFICE, G. SATALINO, M. T. CHIARADIA, "Local residue coupling strategies by neural network for insar phase unwrapping", Proceedings on Aerospace and Remote Sensing , London, 22-26 September 1997, vol. 3217. Postscript file (including figures).
G. NICO, A. REFICE, L. GUERRIERO, N. VENEZIANI, "A new algorithm for interferometric DEM geocoding", Proceedings on Aerospace and Remote Sensing, London, 22-26 September 1997, vol. 3217.tar file (including figures).
L. GUERRIERO, G. PASQUARIELLO, N VENEZIANI, A. REFICE, M. T. CHIARADIA, "Absolute phase determination in SAR interferometry". Proceedings of the International Geoscience and Remote Sensing Symposium (IGARSS '96), pp. 2060-2062, Lincoln, Nebraska, 27-31 May 1996.
L. GUERRIERO, G. PASQUARIELLO, N VENEZIANI, A. REFICE, M. T. CHIARADIA, "Phase unwrapping techniques for INSAR". Symposium on Satellite Remote Sensing III, Vol. 2958, pp. 262-272, Palazzo dei Congressi, Taormina, Italy, 23-27 September 1996.
Year: 2024