The Correction of Phase Unwrapping Errors in Sequences of Multi-Temporal Differential SAR Interferograms

摘要

In this work, the theoretical foundations of a method to identify and routinely correct the phase unwrapping errors affecting a sequence of time-redundant sequence of differential SAR (DInSAR) interferograms are presented and discussed. Although the proposed method has principally been developed to work with differential SAR interferograms that form a triangle-shaped network in the temporal/perpendicular baseline plane, as originally exploited by Extended Minimum Cost Flow (EMF) phase unwrapping (PhU) technique, it may simply be adapted to work with any network of time-redundant interferograms. The fundamental idea is to exploit the phase inconsistencies of triples of (already) unwrapped sequence of interferograms, prior to the application of any inversion for the generation of surface displacement time-series, to independently identify, for every SAR pixels, the 2π-multiple integers corrections to be applied to the unwrapped phases for adjusting the time-inconsistent phase unwrapping errors. This goal is achieved by solving a simple and computationally efficient network-based minimum-cost-flow optimization problem. Some preliminarily experimental results, which have been obtained by processing a sequence of Cosmo-SkyMed (CSK) SAR images collected over the California bay area, are presented.