Maximum likelihood approach for the phase offset estimation in InSAR DEM generation

Synthetic Aperture Radar Interferometry (InSAR) exploits the phase differences (interferogram) of SAR data pairs relevant to the same illuminated area and received by slightly different look angles. Within the InSAR processing chain, it is necessary to calculate a proper phase offset (PhOff) value to add to the unwrapped SAR interferogram. To this aim, different algorithms have been proposed in the literature, which typically exploit the external topography information provided by proper Ground Control Points (GCPs) relevant to the observed scene. In this paper we present a Maximum Likelihood (ML) approach for the InSAR PhOff estimation. It is based on the use of GCPs represented either by Corner Reflectors (CRs) or by the pixels of an available external Digital Elevation Model (DEM) of the observed area. The effectiveness of the proposed approach is assessed on simulated data.