Advanced coherence stacking technique using high resolution TerraSAR-X spotlight data

Measuring the long-term LOS deformation using a multi-pass SAR data stack by standard persistent scatterer (PS) technique has been explored since the late 1990s. Researches have been continuously conducted on increasing the data coverage at non-PS-rich areas. The recently developed SqueeSAR™ technique has validated the potential of extracting useful information from distributed scatterers. With the availability of high resolution TerraSAR-X spotlight data, this technique can benefit greatly from its higher data density and quality. This paper presents an algorithm of optimal parameter estimation at distributed scatterers in a high resolution TerraSAR-X spotlight data, paying particular attention to the covariance matrix estimation. Studies are presented on adaptive sample selection strategy for covariance matrix estimation using different statistical tests (Anderson-Darling). In addition, an adaptive multi-resolution defringe algorithm is introduced to cope with the problem of accurate fringe removal and in turn accurate covariance matrix estimation.