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Advanced stacking techniques and applications in high resolution SAR interferometry

Goel, Kanika (2014) Advanced stacking techniques and applications in high resolution SAR interferometry. Dissertation, Technical University of Munich.

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Official URL: http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:91-diss-20140225-1174987-0-2


Interferometric Synthetic Aperture Radar (InSAR) is a satellite remote sensing technique that provides information about the topography and deformation of the Earth’s surface. In recent years, InSAR’s capabilities have been considerably improved with the launch of high resolution SAR satellites such as TerraSAR-X, TanDEM-X and COSMO-SkyMed. Mapping of urban areas and even single buildings is now facilitated via multitemporal InSAR techniques, for instance, Persistent Scatterer Interferometry (PSI) and SAR Tomography (TomoSAR). These methods exploit long-time coherent scatterers, e.g. the so-called Persistent Scatterers (PSs), and provide elevation and surface displacement measurements with a high precision. However, the density of PSs is low in non-urban areas and it is imperative to increase the spatial density of measured points. Here, high-resolution SAR sensors offer new opportunities. For this purpose, in addition to the PSs, partially coherent Distributed Scatterers (DSs) can be exploited. Various methods such as the Small Baseline Subset Algorithm (SBAS) and SqueeSAR have been proposed to extract information from DSs. However, SBAS is prone to phase unwrapping errors in rural areas and estimates deformation at only low resolution. The alternative technique SqueeSAR can be computationally expensive as it processes all possible interferogram combinations. Accordingly, this thesis addresses the development of advanced stacking techniques in high resolution SAR interferometry, with a focus on complex areas that are difficult to process using conventional techniques. To this end, first, a new method has been developed for deformation monitoring of DSs at object resolution in non-urban areas. It applies adaptive spatial filtering to improve the differential interferometric phase, followed by deformation estimation using an L1-norm based SBAS approach that is more robust to phase unwrapping errors. Second, an alternative approach for mean deformation velocity mapping of DSs has been proposed for highly decorrelated areas, wherein, wrapped interferograms (with small baselines) are directly used and the deformation velocity is mapped at a suitable object resolution. It includes identification of homogenous patches, estimation of deformation velocity gradients for these patches and then, model-based deformation integration to obtain spatially dense deformation velocity estimates. Lastly, a fusion of TerraSAR-X and TanDEM-X data stacks has been presented for complex urban area monitoring exploiting both PSs and DSs. TerraSAR-X allows monostatic acquisitions and in conjunction with the TanDEM-X satellite, bistatic acquisitions are now also possible. Thus, stacks of monostatic repeat-pass and bistatic single-pass interferograms are available. The bistatic interferograms are of high quality and are free from deformation, atmosphere and temporal decorrelation. By properly integrating the data stacks, an improved estimation of topography and deformation is possible. However, the independent processing and subsequent simple combination of the bistatic and monostatic data is not beneficial. Standard TanDEM-X Digital Elevation Models (DEMs) are inaccurate in dense metropolitan areas because of phase unwrapping errors. These errors occur due to height discontinuities and geometrical limitations such as radar layover. Therefore, the joint processing of TerraSAR-X and TanDEM-X data has been investigated. The developed techniques have been demonstrated using TerraSAR-X/TanDEM-X data from various test sites and a high performance has been proven. The results show an improved utilization of the information hidden in the data and an extension of the applicability of existing techniques for mapping displacement and topography in difficult test areas. The proposed methods can benefit from future SAR systems with even higher resolution.

Item URL in elib:https://elib.dlr.de/94507/
Document Type:Thesis (Dissertation)
Title:Advanced stacking techniques and applications in high resolution SAR interferometry
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Goel, KanikaKanika.Goel (at) dlr.deUNSPECIFIED
Journal or Publication Title:Advanced stacking techniques and applications in high resolution SAR interferometry
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Number of Pages:153
Keywords:Earth Observation, Spaceborne Remote Sensing, Interferometric Synthetic Aperture Radar (InSAR), InSAR Stacking Techniques, Deformation Monitoring, Digital Elevation Model (DEM), Persistent Scatterer (PS), Distributed Scatterer (DS), TanDEM-X, TerraSAR-X
Institution:Technical University of Munich
Department:Ingenieurfakultät Bau Geo Umwelt (BGU)
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Vorhaben hochauflösende Fernerkundungsverfahren (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > SAR Signal Processing
Deposited By: Goel, Kanika
Deposited On:12 Jan 2015 15:13
Last Modified:31 Jul 2019 19:51

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