Multibaseline phase unwrapping for INSAR topography estimation

Multibaseline Synthetic Aperture Radar (SAR) Interferometry (INSAR) can be successfully exploited for automatic phase unwrapping and high quality Digital Elevation Model (DEM) reconstruction. The information coming from several interferograms with different baselines increases the elevation ambiguity interval and allows automatic phase unwrapping. The height of each pixel in the image is considered as a random variable: a Maximum-Likelihood (ML) estimation of the height is carried out by exploiting the probability density function of the inteferometric phase, that depends on the local coherence value. After phase unwrapping is possible to combine all the information available, getting a combined DEM that is more reliable than each single DEM. Results obtained using ERS-1/2 SAR data gathered over Vesuvius and Etna are presented. In both cases an accuracy better than 8 meters was obtained