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Tom Rune Lauknes, Stanford University (United States)
Tom Rune Lauknes, Norut (Norway)
Piyush Shanker A., Stanford University (United States)
Howard Zebker, Stanford University (United States)
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Recently developed InSAR processing approaches that use data from multiple acquisitions to retrieve deformation time-series include persistent scatterer (PSI) and small baseline (SBAS) methods. Each has been optimized assuming a specific scattering mechanism. PSI methods work by identifying the ground resolution elements that are dominated by a single scatterer. A persistent scatterer exhibits reduced baseline and temporal decorrelation due to its stable, point-like scattering mechanism. Interferograms formed with a single master scene are analyzed at single look resolution in order to maximize the signal-to-noise ratio (SNR) of the resolution elements containing a single dominant scatterer. In contrast, small baseline methods assume a distributed scattering mechanism and use common band spectral filtering and complex multi-looking of the interferograms in order to improve the SNR. In order to reduce spatial decorrelation, all possible interferograms with a perpendicular baseline below a certain threshold are used in the analysis. The SBAS interferogram time series is inverted for deformation time series retrieval.
Various research groups have previously demonstrated the effectiveness of both PSI and SBAS methods in obtaining deformation time series in urban areas. We apply these approaches to natural terrain, where we assume that a combination of point target and distributed scattering mechanisms occur. In our proposed method, combining the benefits of both the PSI and the SBAS algorithms helps resolve the deformation signal in areas where different scattering mechanisms exist. By using aspects of persistent scatterer and small baseline approaches, we are able to extend the spatial coverage of each, and thereby increase InSAR applicability in different terrain types. We present here a new hybrid algorithm combining the advantages from both approaches to analyze a stack of SAR scenes. The maximum likelihood PSI selection method [Shanker and Zebker, GRL 2007] is used for identifying the persistent scatterers, while the small baseline subset algorithm (SBAS) [Berardino et al., IEEE TGARS 2002] is used to resolve deformation in areas where distributed scattering mechanisms dominates. The SBAS results are combined with the identified PS in order to improve spatial coverage. We apply the new approach to study a landslide region in Northern Norway.
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