Sentinel-1 data exploitation for terrain deformation monitoring

Persistent Scatterer interferometry (PSI) is a group of advanced differential interferometric Synthetic Aperture Radar (SAR) techniques used to measure and monitor terrain deformation. Sentinel-1 has improved the data acquisition throughout and, compared to previous sensors, increased considerably the Differential Interferometric SAR (DInSAR) and PSI deformation monitoring potential. The effect of the refractive atmosphere on the interferometric phase and phase unwrapping ambiguity are two critical issues of InSAR. The low density of Persistent Scatterer (PS) in non-urban areas, another critical issue, has inspired the development of alternative approaches and refinement of the PS chains. Along with the efforts to develop methods to mitigate the three above-mentioned problems, the work presented in this thesis also deals with the presence of a new signal in multilooked interferograms which cannot be explained by noise, atmospheric or earth surface topography changes. This paper describes a method for atmospheric phase screen estimation using rain station weather data and three different data driven procedures to obtain terrain deformation maps. These approaches aim to exploit Sentinel-1 highly coherent interferograms and their short revisit time. The first method called the splitting makes uses of the power spectrum of the interferograms to split the signals into high and low frequency, and following a mutually exclusive consecutive processing chain for the two sets. This approach has resulted in greater density of PSs with decreased phase unwrapping errors. The second approach, called Direct Integration (DI), aims at providing a very fast and straightforward approach to screen wide areas and easily detect active areas. This approach fully exploits the coherent interferograms from the consecutive images provided by Sentinel-1 resulting in a very high sampling density. However, it lacks robustness and its usability lays on the operator experience. The third method, called PSIG (Persistent Scatterer Interferometry Geomatics) short temporal baseline, provides a constrained application of the PSIG chain, the CTTC approach to the PSI. It uses short temporal baseline interferograms and do not assume any deformation model for point selection. It is also quite a straightforward approach and a perfect complement to the direct integration approach. It improves the performances of the standard PSIG approach, increasing the PS density and providing robust measurements. The effectiveness of the approaches is illustrated through analyses performed on different test sites.La técnica Persistent Scatterer Interferometry (PSI) es un grupo de técnicas avanzadas de radar de apertura sintética interferométrica diferencial (SAR) que se utiliza para medir y monitorear losmovimientos del terreno. Sentinel-1 ha mejorado sensiblemente la adquisición de datos y, en comparación con los sensores SAR anteriores, ha aumentado considerablemente el potencial uso de la interferometría diferencial SAR y del PSI para medir y monitorizar desplazamientos del terreno. El efecto de la atmósfera sobre la fase interferométrica y la naturaleza ambigua de esta son dos cuestiones críticas de InSAR. Además, la baja densidad de Persistent Scatterer (PSs) en áreas no urbanas, es otro tema crítico que ha inspirado el desarrollo de enfoques alternativos y el refinamiento de las cadenas PS existentes. Junto con los esfuerzos por desarrollar métodos para mitigar los tres problemas antes mencionados, el trabajo presentado en esta tesis también aborda la presencia de una nueva señal en interferogramas multilooked que no puede explicarse por cambios de ruido, atmosféricos o topográficos de la superficie terrestre. Esta tesis describe un método para la estimación de la fase atmosférica utilizando datos meteorológicos adquiridos in-situ y tres aproximaciones diferentes basadas en datos Sentinel-1 para obtener mapas de deformación del terreno. Estos enfoques tienen como objetivo explotar los interferogramas altamente coherentes proporcionados por Sentinel-1 gracias a su corto tiempo de revisita. El primer método llamado división hace uso de filtros en el dominico frecuencial de los interferogramas para dividir las señales en alta y baja frecuencia, y siguiendo una cadena de procesamiento consecutiva independiente para cada clase. Este enfoque ha dado como resultado una mejora substancial de PS minimizando los errores debidos al desenrollado de fase. El segundo enfoque, llamado Integración Directa (DI), tiene como objetivo proporcionar un enfoque muy rápido y sencillo para examinar áreas amplias y detectar fácilmente áreas activas. Este enfoque aprovecha al máximo los interferogramas coherentes de las imágenes consecutivas proporcionadas por Sentinel-1, lo que da como resultado una densidad de muestreo muy alta. Sin embargo, carece de robustez y su usabilidad depende de la experiencia del operador. El tercer método, llamado PSIG (Persistent Scatterer Interferometry Geomatics) de línea de base temporal corta, proporciona una aplicación restringida de la cadena PSIG, el enfoque CTTC para el PSI. Utiliza interferogramas de línea base temporales cortos y no asume ningún modelo de deformación para la selección de puntos. Su uso es complementario al enfoque de integración directa proporcionando robustez en las zonas. Mejora el rendimiento del enfoque estándar de PSIG, aumentando la densidad de PS y proporcionando mediciones robustas. La efectividad de los enfoques se ilustra a través de análisis realizados en diferentes sitios de prueba.Postprint (published version

Interferomeetriline tehisavaradar kui vahend turbaalade pinna dünaamika jälgimiseks

Väitekirja elektrooniline versioon ei sisalda publikatsiooneSood on unikaalsed ökosüsteemid, kus turba ladestumise käigus seotakse pikaajaliselt süsinikku. Üleilmselt on soodes seotud süsiniku kogus, mis võrdub peaaegu poolega hetkel atmosfääris olevast. Tasakaalu süsiniku sidumise ja lendumise vahel mõjutab soodes kõige enam veetase, mistõttu veerežiimi muutudes võivad sood muutuda süsiniku talletajast kasvuhoonegaaside õhku paiskajaks. Tehisavaradar (SAR) on aktiivne mikrolainealas töötav kaugseiresüsteem, mille kasutamine võimaldaks turbaalade ülemaailmset seiret. SAR näeb läbi pilvede, katab korraga suure ala, on hea ruumilise lahutuse ja tiheda ajalise katvusega. Interferomeetriline SAR (InSAR) on uudne meetod, mis võimaldab mõõta maapinna kõrgusmuutusi, tuginedes radarisignaali pool läbitava teekonna pikkusete erinevusele kahest samast kohast, aga eri aegadel tehtud pildi vahel. Tulemuseks on kõrgusmuutuse pilt (interferogramm), kõrvalsaaduseks on koherentsuse pilt, mis kirjeldab võrreldavate piltide ruumimustrite sarnasust. Meetodi kitsaskohaks on suurte kõrgusmuutuste õigesti hindamine. Töö eesmärk oli katsetada InSAR meetodi kasutusvõimaluse piire ja rakendada uusi teadmisi rabade seirel. Uurisin: 1) raba veetaseme mõju koherentsusele; 2) freesturba tootmisega kaasnevat pinna muutuse mõju koherentsusele; 3) InSAR meetodi usaldusväärsust raba pinna kõrguse muutuse hindamisel. Tulemused näitavad, et koherentsustest on kasu soode veerežiimi uurimisel, kuid see ei sobi pinnase niiskuse otseseks mõõtmiseks. Koherentsust saab kasutada turba tootmise seireks, võttes arvesse SAR-ist ja turba tootmise protsessist tulenevaid piiranguid. Töös on visandatud seiremetoodika, mis võimaldab eristada aktiivseid turbatootmisalasid kasutuses välja jäänud aladest ja jälgida turba tootmise intensiivsust, edendamaks tõhusamat ressursikasutust. InSAR meetodil maapinna kõrguse mõõtmised tavapärase 5,6 sentimeetrise lainepikkuse juures ei ole rabas usaldusväärsed. Katsetatud InSAR meetodid ei suutnud kiiresti toimuvaid suuri kõrgusmuutusi õigesti hinnata. Sarnaselt varasematele uuringutele oleks selline viga jäänud avastamata, kui meil poleks võrdluseks olnud maapealseid kõrgusandmeid. Tõenäoliselt võiks soos maapinna kõrguse muutuse hindamiseks paremini sobida lähitulevikku planeeritud pikalainelised (24 cm) radarsatelliidi missioonid.  Peatlands are significant in regard to climate change because peatlands may switch from being a net carbon sink to an emitter of greenhouse gases. The delicate carbon balance in peatlands is controlled by the peatland water table. Peatland soils contain globally nearly as much carbon as a half of what is currently in the atmosphere. Synthetic Aperture Radar (SAR) is an active microwave remote sensing system which has potential for global peatland monitoring. SAR can penetrate through clouds, covers simultaneously a vast area at high spatial resolution and has a short revisit cycle. Interferometric SAR (InSAR) is an emerging technique to measure surface height changes utilising the difference in the path length that the signal travels between SAR acquisitions of the same target from the same orbital position at different times. The resultant deformation image does not show the absolute change in the path length but the result is ambiguously wrapped in cycles corresponding to half of the signal wavelength, complicating estimation of larger changes. A co-product of InSAR processing is the coherence image, describing the similarity of the spatial patterns in the images. The objective of my dissertation is testing the limits of InSAR and, built on it, improving peatland monitoring. It was studied: 1) coherence response to the water table in raised bogs; 2) coherence response to peat surface alteration caused by the milled peat production; 3) reliability of InSAR deformation estimates in open bogs. Based on the results, coherence could be used as aid to understanding of hydrologic conditions in bogs but it is unsuitable for direct moisture retrieval. Coherence can be used to monitor peat extraction, considering intrinsic limitations posed by the SAR and the peat extraction process. The ambiguity problem makes displacement measurements at the conventional 5.6 cm wavelength unreliable in bogs. A solution could be the planned long wavelength (24 cm) SAR missions.https://www.ester.ee/record=b550580

Urban Deformation Monitoring using Persistent Scatterer Interferometry and SAR tomography

This book focuses on remote sensing for urban deformation monitoring. In particular, it highlights how deformation monitoring in urban areas can be carried out using Persistent Scatterer Interferometry (PSI) and Synthetic Aperture Radar (SAR) Tomography (TomoSAR). Several contributions show the capabilities of Interferometric SAR (InSAR) and PSI techniques for urban deformation monitoring. Some of them show the advantages of TomoSAR in un-mixing multiple scatterers for urban mapping and monitoring. This book is dedicated to the technical and scientific community interested in urban applications. It is useful for choosing the appropriate technique and gaining an assessment of the expected performance. The book will also be useful to researchers, as it provides information on the state-of-the-art and new trends in this fiel

Innovative Techniques for the Retrieval of Earth’s Surface and Atmosphere Geophysical Parameters: Spaceborne Infrared/Microwave Combined Analyses

With the advent of the first satellites for Earth Observation: Landsat-1 in July 1972 and ERS-1 in May 1991, the discipline of environmental remote sensing has become, over time, increasingly fundamental for the study of phenomena characterizing the planet Earth. The goal of environmental remote sensing is to perform detailed analyses and to monitor the temporal evolution of different physical phenomena, exploiting the mechanisms of interaction between the objects that are present in an observed scene and the electromagnetic radiation detected by sensors, placed at a distance from the scene, operating at different frequencies. The analyzed physical phenomena are those related to climate change, weather forecasts, global ocean circulation, greenhouse gas profiling, earthquakes, volcanic eruptions, soil subsidence, and the effects of rapid urbanization processes. Generally, remote sensing sensors are of two primary types: active and passive. Active sensors use their own source of electromagnetic radiation to illuminate and analyze an area of interest. An active sensor emits radiation in the direction of the area to be investigated and then detects and measures the radiation that is backscattered from the objects contained in that area. Passive sensors, on the other hand, detect natural electromagnetic radiation (e.g., from the Sun in the visible band and the Earth in the infrared and microwave bands) emitted or reflected by the object contained in the observed scene. The scientific community has dedicated many resources to developing techniques to estimate, study and analyze Earth’s geophysical parameters. These techniques differ for active and passive sensors because they depend strictly on the type of the measured physical quantity. In my P.h.D. work, inversion techniques for estimating Earth’s surface and atmosphere geophysical parameters will be addressed, emphasizing methods based on machine learning (ML). In particular, the study of cloud microphysics and the characterization of Earth’s surface changes phenomenon are the critical points of this work

Advanced exploitation of Sentinel-1 data for supporting landslide risk analysis

Tesi en modalitat de compendi de publicacionsSatellite Synthetic Aperture Radar Interferometry (InSAR) and Persistent Scatterer Interferometry (PSI) are now consolidated tools for ground movement detection and monitoring. Sentinel-1 (S1) is the first satellite providing free data access and ensuring a regular acquisition worldwide, every 6 days, increasing its potential for long-term monitoring applications. Several regional and national ground motion services are already active, providing products based on S1 data. Soon in 2022 the first European Ground Motion Service (EGMS) will be available and freely provide a displacement map over the whole Europe, with annual updates. This implies a strong expansion of availability of PSI-based displacement maps and an easy access for anyone, with an increasing interest among a wider range of users, including public or governmental institutions, academia, industry, and citizens. The analysis and interpretation of this amount of data is difficult and time consuming, mostly for non-expert InSAR users. The objective of this work is developing methodologies to simplify the operational use of PSI displacement maps, generating derived products with a clear message, easy-to-interpret, and fast to read. We propose a method to be applied over regional scale PSI displacement maps, to fast detect the most significant Active Deformation Areas (ADAs). The ADA map is a first product that allows a fast focusing on the active areas, to prioritize further analysis and investigation. Starting from the ADAs, the potential phenomena are attributed to each area through a preliminary interpretation based on auxiliary data, to derive the Geohazard Activity Map. In this work, a methodology to include the ADA information in the Civil Protection Activities is proposed, with the main output called Vulnerable Elements Activity Maps (VEAM). An application of the VEAM is illustrated in the Canary Islands. Furthermore, the ADA map is used in the Valle d'Aosta Region (Northern of Italy) to generate vulnerability and potential loss maps. Finally, a methodology to derive potential damage maps of the exposed buildings, based on the spatial gradients of movement, is proposed, and applied in a coastal area of the Province of Granada (Spain). A pack of software tools has been developed based on the proposed methods to extract ADA and then classify them to generate a Geohazard Activity Map. The set of tools is called ADATools, it is open-access, easy to use and fast, improving the operational exploitation of PSI regional-scale displacement maps. All the methodologies have been developed in the frame of several European projects (Safety, U-Geohaz, MOMIT and RISKCOAST), and are aimed at supporting the multi-scale territorial management and risk analysis activities, with a specific focus on landslides.La interferometría satelital radar (InSAR) y la interferometría de dispersores persistentes (PSI) son herramientas consolidadas para la detección y el monitoreo de movimientos de la superficie de la Tierra. Sentinel-1 (S1) es el primer satélite que proporciona acceso gratuito a los datos y garantiza una adquisición regular en todo el mundo, cada 6 días, aumentando su potencial para aplicaciones de monitoreo a largo plazo. Varios Ground Motion Services regionales y nacionales ya están activos, proporcionando productos basados en datos S1. Pronto, en 2022, el primer servicio europeo (European Ground Motion Service - EGMS) estará disponible y facilitará libremente un mapa de movimientos de toda Europa, con actualizaciones anuales. Esto implica un aumento de la disponibilidad de mapas de movimientos basados en PSI y un fácil acceso para cualquier persona, con un interés creciente entre una amplia gama de usuarios, incluyendo instituciones públicas o gubernamentales, academias, industrias y ciudadanos. El análisis e interpretación de esta cantidad de datos es difícil y consume mucho tiempo, mayormente para usuarios no expertos en la técnica. El objetivo de este trabajo es desarrollar metodologías para simplificar el uso operativo de los mapas de desplazamiento PSI, generando productos derivados con un mensaje claro, fácil de interpretar, y rápido de leer. Se propone un método para detectar rápidamente las Áreas de Deformación Activas (ADAs) más significativas, a partir de mapas de desplazamiento PSI de escala regional. El mapa de las ADAs es un primer producto que permite un enfoque rápido en las áreas activas, útil para priorizar el análisis y las investigaciones adicionales. A partir de las ADAs, se propone una interpretación preliminar basada en datos auxiliares, que atribuye a cada área el fenómeno que está detrás del movimiento, generando el Geohazard Activity Map (GAM). Después, se propone una metodología para incluir la información de las ADAs en las actividades de protección civil, generando los Vulnerable Element Activity Maps (VEAM), a través de su aplicación en las Islas Canarias. Además, el mapa de las ADAs se utiliza en la región de Valle D'Aosta (norte de Italia) para generar mapas de vulnerabilidad y posibles pérdidas económicas. Finalmente, se propone una metodología para obtener mapas de daños potenciales de los edificios expuestos, basados en los gradientes espaciales de movimiento, y se aplica en un área costera de la provincia de Granada (España). A partir de los métodos propuestos para extraer y clasificar las ADAs, y de otros métodos de análisis existentes, se ha desarrollado un paquete de herramientas, los ADAtools, de acceso abierto, fáciles de usar y rápidas, que optimizan la explotación operativa de los mapas de desplazamiento de escala regional. Todas las metodologías se han desarrollado en el marco de varios proyectos europeos (Safety, U-Geohaz, MOMIT y RISKCOAST), y están dirigidos a apoyar las actividades de gestión territorial y análisis de riesgos, con un enfoque específico a los deslizamientos de tierra.Postprint (published version

Advanced exploitation of Sentinel-1 data for supporting landslide risk analysis

Tesi en modalitat de compendi de publicacionsSatellite Synthetic Aperture Radar Interferometry (InSAR) and Persistent Scatterer Interferometry (PSI) are now consolidated tools for ground movement detection and monitoring. Sentinel-1 (S1) is the first satellite providing free data access and ensuring a regular acquisition worldwide, every 6 days, increasing its potential for long-term monitoring applications. Several regional and national ground motion services are already active, providing products based on S1 data. Soon in 2022 the first European Ground Motion Service (EGMS) will be available and freely provide a displacement map over the whole Europe, with annual updates. This implies a strong expansion of availability of PSI-based displacement maps and an easy access for anyone, with an increasing interest among a wider range of users, including public or governmental institutions, academia, industry, and citizens. The analysis and interpretation of this amount of data is difficult and time consuming, mostly for non-expert InSAR users. The objective of this work is developing methodologies to simplify the operational use of PSI displacement maps, generating derived products with a clear message, easy-to-interpret, and fast to read. We propose a method to be applied over regional scale PSI displacement maps, to fast detect the most significant Active Deformation Areas (ADAs). The ADA map is a first product that allows a fast focusing on the active areas, to prioritize further analysis and investigation. Starting from the ADAs, the potential phenomena are attributed to each area through a preliminary interpretation based on auxiliary data, to derive the Geohazard Activity Map. In this work, a methodology to include the ADA information in the Civil Protection Activities is proposed, with the main output called Vulnerable Elements Activity Maps (VEAM). An application of the VEAM is illustrated in the Canary Islands. Furthermore, the ADA map is used in the Valle d'Aosta Region (Northern of Italy) to generate vulnerability and potential loss maps. Finally, a methodology to derive potential damage maps of the exposed buildings, based on the spatial gradients of movement, is proposed, and applied in a coastal area of the Province of Granada (Spain). A pack of software tools has been developed based on the proposed methods to extract ADA and then classify them to generate a Geohazard Activity Map. The set of tools is called ADATools, it is open-access, easy to use and fast, improving the operational exploitation of PSI regional-scale displacement maps. All the methodologies have been developed in the frame of several European projects (Safety, U-Geohaz, MOMIT and RISKCOAST), and are aimed at supporting the multi-scale territorial management and risk analysis activities, with a specific focus on landslides.La interferometría satelital radar (InSAR) y la interferometría de dispersores persistentes (PSI) son herramientas consolidadas para la detección y el monitoreo de movimientos de la superficie de la Tierra. Sentinel-1 (S1) es el primer satélite que proporciona acceso gratuito a los datos y garantiza una adquisición regular en todo el mundo, cada 6 días, aumentando su potencial para aplicaciones de monitoreo a largo plazo. Varios Ground Motion Services regionales y nacionales ya están activos, proporcionando productos basados en datos S1. Pronto, en 2022, el primer servicio europeo (European Ground Motion Service - EGMS) estará disponible y facilitará libremente un mapa de movimientos de toda Europa, con actualizaciones anuales. Esto implica un aumento de la disponibilidad de mapas de movimientos basados en PSI y un fácil acceso para cualquier persona, con un interés creciente entre una amplia gama de usuarios, incluyendo instituciones públicas o gubernamentales, academias, industrias y ciudadanos. El análisis e interpretación de esta cantidad de datos es difícil y consume mucho tiempo, mayormente para usuarios no expertos en la técnica. El objetivo de este trabajo es desarrollar metodologías para simplificar el uso operativo de los mapas de desplazamiento PSI, generando productos derivados con un mensaje claro, fácil de interpretar, y rápido de leer. Se propone un método para detectar rápidamente las Áreas de Deformación Activas (ADAs) más significativas, a partir de mapas de desplazamiento PSI de escala regional. El mapa de las ADAs es un primer producto que permite un enfoque rápido en las áreas activas, útil para priorizar el análisis y las investigaciones adicionales. A partir de las ADAs, se propone una interpretación preliminar basada en datos auxiliares, que atribuye a cada área el fenómeno que está detrás del movimiento, generando el Geohazard Activity Map (GAM). Después, se propone una metodología para incluir la información de las ADAs en las actividades de protección civil, generando los Vulnerable Element Activity Maps (VEAM), a través de su aplicación en las Islas Canarias. Además, el mapa de las ADAs se utiliza en la región de Valle D'Aosta (norte de Italia) para generar mapas de vulnerabilidad y posibles pérdidas económicas. Finalmente, se propone una metodología para obtener mapas de daños potenciales de los edificios expuestos, basados en los gradientes espaciales de movimiento, y se aplica en un área costera de la provincia de Granada (España). A partir de los métodos propuestos para extraer y clasificar las ADAs, y de otros métodos de análisis existentes, se ha desarrollado un paquete de herramientas, los ADAtools, de acceso abierto, fáciles de usar y rápidas, que optimizan la explotación operativa de los mapas de desplazamiento de escala regional. Todas las metodologías se han desarrollado en el marco de varios proyectos europeos (Safety, U-Geohaz, MOMIT y RISKCOAST), y están dirigidos a apoyar las actividades de gestión territorial y análisis de riesgos, con un enfoque específico a los deslizamientos de tierra.Enginyeria del terren

Advanced pixel selection and optimization algorithms for Persistent Scatterer Interferometry (PSI)

Tesi amb diferents seccions retallades per dret de l'editorPremi Extraordinari de Doctorat, promoció 2018-2019. Àmbit de les TICGround deformation measurements can provide valuable information for minimization of associated loss and damage caused by natural and environmental hazards. As a kind of remote sensing technique, Persistent Scatterer Interferometry (PSI) SAR is able to measure ground deformation with high spatial resolution, efficiently. Moreover, the ground deformation monitoring accuracy of PSI techniques can reach up to millimeter level. However, low coherence could hinderthe exploitation of SAR data, and high-accuracy deformation monitoring can only be achieved by PSI for high quality pixels. Therefore, pixel optimization and identification of coherent pixels are crucial for PSI techniques. In this thesis, advanced pixel selection and optimization algorithms have been investigated. Firstly, a full-resolution pixel selection method based on the Temporal Phase Coherence (TPC) has been proposed. This method first estimates noise phase term of each pixel at interferogram level. Then, for each pixel, its noise phase terms of all interferograms are used to assess this pixel’s temporal phase quality (i.e., TPC). In the next, based on the relationship between TPC and phase Standard Deviation (STD), a threshold can be posed on TPC to identify high phase quality pixels. This pixel selection method can work with both Deterministic Scatterers (PSs) and Distributed Scatterers (DSs). To valid the effectiveness of the developed method, it has been used to monitor the Canillo (Andorra) landslide. The results show that the TPC method can obtained highest density of valid pixels among the employed three approaches in this challenging area with X-band SAR data. Second, to balance the polarimetric DInSAR phase optimization effect and the computation cost, a new PolPSI algorithm is developed. This proposed PolPSI algorithm is based on the Coherency Matrix Decomposition result to determine the optimal scattering mechanism of each pixel, thus it is named as CMD-PolPSI. CMDPolPSI need not to search for solution within the full space of solution, it is therefore much computationally faster than the classical Equal Scattering Mechanism (ESM) method, but with lower optimization performance. On the other hand, its optimization performance outperforms the less computational costly BEST method. Third, an adaptive algorithm SMF-POLOPT has been proposed to adaptive filtering and optimizing PolSAR pixels for PolPSI applications. This proposed algorithm is based on PolSAR classification results to firstly identify Polarimetric Homogeneous Pixels (PHPs) for each pixel, and at the same time classify PS and DS pixels. After that, DS pixels are filtered by their associated PHPs, and then optimized based on the coherence stability phase quality metric; PS pixels are unfiltered and directly optimized based on the DA phase quality metric. SMF-POLOPT can simultaneously reduce speckle noise and retain structures’ details. Meanwhile, SMF-POLOPT is able to obtain much higher density of valid pixels for deformation monitoring than the ESM method. To conclude, one pixel selection method has been developed and tested, two PolPSI algorithms have been proposed in this thesis. This work make contributions to the research of “Advanced Pixel Selection and Optimization Algorithms for Persistent Scatterer InterferometryLes mesures de deformació del sòl poden proporcionar informació valuosa per minimitzar les pèrdues i els danys associats causats pels riscos naturals i ambientals. Com a tècnica de teledetecció, la interferometria de dispersors persistents (Persistent Scatter Interferometry, PSI) SAR és capaç de mesurar de forma eficient la deformació del terreny amb una alta resolució espacial. A més, la precisió de monitorització de la deformació del sòl de les tècniques PSI pot arribar a arribar a nivells del mil·límetre. No obstant això, una baixa coherència pot dificultar l’explotació de dades SAR i el control de deformació d’alta precisió només es pot aconseguir mitjançant PSI per a píxels d’alta qualitat. Per tant, l’optimització de píxels i la identificació de píxels coherents són crucials en les tècniques PSI. En aquesta tesi s¿han investigat algorismes avançats de selecció i optimització de píxels. En primer lloc, s'ha proposat un mètode de selecció de píxels de resolució completa basat en la coherència temporal de fase (Temporal Phase Coherence, TPC). Aquest mètode estima per primera vegada el terme de fase de soroll de cada píxel a nivell d’interferograma. A continuació, per a cada píxel, s'utilitzen els termes de la fase de soroll de tots els interferogrames per avaluar la qualitat de fase temporal d'aquest píxel (és a dir, TPC). A la següent, basant-se en la relació entre el TPC i la desviació estàndard de fase (STD), es pot plantejar un llindar de TPC per identificar píxels de qualitat de fase alta. Aquest mètode de selecció de píxels es capaç de detectar tant els dispersors deterministes (PS) com els distribuïts (DS). Per validar l’eficàcia del mètode desenvolupat, s’ha utilitzat per controlar l’esllavissada de Canillo (Andorra). Els resultats mostren que el mètode TPC pot obtenir la major densitat de píxels vàlids, comparat amb els mètodes clàssics de selecció, en aquesta àrea difícil amb dades de SAR de banda X. En segon lloc, per equilibrar l’efecte d’optimització de fase DInSAR polarimètrica i el cost de càlcul, es desenvolupa un nou algorisme de PolPSI. Aquest algorisme proposat de PolPSI es basa en el resultat de la descomposició de la matriu de coherència per determinar el mecanisme de dispersió òptim de cada píxel, de manera que es denomina CMD-PolPSI. CMDPolPSI no necessita buscar solucions dins de l’espai complet de la solució, per tant, és molt més eficient computacionalment que el mètode clàssic de mecanismes d’igualtat de dispersió (Equal Scattering Mechanism, ESM), però amb un efecte d’optimització no tant òptim. D'altra banda, el seu efecte d'optimització supera el mètode BEST, el que te un menor cost computacional. En tercer lloc, s'ha proposat un algoritme adaptatiu SMF-POLOPT per al filtratge adaptatiu i l'optimització de píxels PolSAR per a aplicacions PolPSI. Aquest algorisme proposat es basa en els resultats de classificació PolSAR per identificar primer els píxels homogenis polarimètrics (PHP) per a cada píxel i, alhora, classificar els píxels PS i DS. Després d'això, els píxels DS es filtren pels seus PHP associats i, a continuació, s'optimitzen en funció de la mètrica de qualitat de la fase d'estabilitat de coherència; els píxels classificats com PS no es filtren i s'optimitzen directament en funció de la mètrica de qualitat de la fase DA. SMF-POLOPT pot reduir simultàniament el soroll de la fase interferomètrica i conservar els detalls de les estructures. Mentrestant, SMF-POLOPT aconsegueix obtenir una densitat molt més alta de píxels vàlids per al seguiment de la deformació que el mètode ESM. Per concloure, en aquesta tesi s’ha desenvolupat i provat un mètode de selecció de píxels, i s’han proposat dos algoritmes PolPSI. Aquest treball contribueix a la recerca en "Advanced Pixel Selection and Optimization Algorithms for Persistent Scatterer Interferometry"Postprint (published version

From site-scale to large areas monitoring of ground deformation phenomena by integration of different DInSAR techniques in Crotone Province (Southern Italy)

One of the most significant aims of this research project has been to apply SAR methods for the monitoring, the investigation and the evaluation of ground deformation phenomena in the Crotone province (Southern Italy). In detail, landslides and subsidence are the most remarkable and dangerous natural hazards in the study area, affecting people, buildings and main infrastructures. The intention was to show the potential of Differential Interferometry SAR (DInSAR) techniques for the detection and the estimation of the velocities and of the deformation of surface displacements, both on very local scale (slope scale) and on wide areas (kilometre-size extension). Such aim is achievable through the integration of DInSAR techniques along with conventional monitoring tools. The general idea of the project has been to assess the landslide hazard in selected areas of the Crotone province and to update the related landslide inventory map of the area, dated back to 2006, by means of DInSAR techniques. These goals have been reached through the comprehension and the understanding of the movements, on one hand on a very local scale (slope), and on the other hand, on a wide-area scale (the whole Crotone province). Additionally, two other case studies of subsidence, originated by different sources, have been studied with interferometry techniques, showing the suitability of such methods for other types of ground deformation. Several Multi Temporal Interferometry (MTI, Wasowski & Bovenga, 2014) approaches have been here applied, in order to investigate and analyze displacements present in the area, and the integration with “conventional” methods, such as inclinometers, piezometers and geomorphological surveys, turned out to be relevant for these purposes, providing very precise information about the nature and causes of ground deformation