Multipass SAR interferometry. A tool for geologic analysis

This paper investigates how the information content of repeat pass satellit e SAR interferometric (INSAR) data can be used to provide the geologist wit h a tool which can improve his ability and efficacy in the geologic analysi s of SAR imagery. INSAR processing produces interferometric fringes, cohere nce and amplitude images. To produce an interferometric DEM phase unwrappin g is a critical step. For phase unwrapping, we propose the WLMS (Weighted L east Mean Square) estimation of the phase, which is a generalization of the least-mean square method. The crucial step in WLMS approach is the weighti ng procedure. We propose a weighting algorithm based on the fusion of a pri ori information extracted from different interferometric products. These di fferent information channels-DEM, amplitude and coherence-can be effectivel y fused to convey information to the geologic interpreter using 3D stereosc opic visualization; SAR stereo pairs were artificially generated using the interferometric DEM and the intensity image or the coherence image of the a rea overlaid. In order to ascertain the performance of the procedure a numb er of tests were carried out over various sites in Matese (Southern Italy), which has a fairly demanding topography, using ERS SAR tandem data. The re sults demonstrate that WLMS unwrapping method is sufficiently robust in cap turing the morphology of the area and that stereoscopic visualization great ly facilitates geologic interpretation and the observation of detailed feat ures of the terrain.