Batch filtering of multi-baseline SAR interferograms

In current Interferometric synthetic aperture radar (InSAR) applications, small baseline subsets (SBAS) technique is frequently applied by setting both temporal baseline and perpendicular baseline thresholds to select interferograms with less decorrelations. However, in real cases, some high quality interferograms may be discarded and some low quality interferograms may be included based on the former thresholds. On the other hand, with the emergence of Big SAR data era, it is time-consuming and bothersome to determine real high quality interferograms manually or visually. Therefore, this paper proposes a means to determine high quality interferograms based on two thresholds, the one is the coherence of filtered interferograms, and the other is the percentage of high coherence points in interferograms. To this ends, first, robust estimation of coherence matrix of multi-baseline InSAR stack is adopted to restrain some heterogeneous points. Second, coherence matrix for each pixel is decomposed to get dominant phase signal based on the SAR scatterer mechanism. Once the interferograms are determined, phase unwrapping is easily conducted based on the high quality coherent points. Real eight scenes TerraSAR-X data over one land subsidence region is applied to verify of the proposed method.