Multi-baseline SAR Interferometry using Elaboration of Amplitude and Phase Data

Abstract

Multi-baseline interferometric SyntheticAperture Radar (In-SAR) systems can be exploited to estimate the Digital Elevation Model (DEM) of the observed scene without ambiguities and with an increased accuracy, even in the case of high sloped ground regions. The techniques usually used exploit only the interferometric phase information and they are based on Maximum Likelihood (ML) estimation. An important problem to be taken into account is the mutual correlation of the (complex) interferometric images which impedes the closed form evaluation of the interferometric phases likelihood function. Moreover the statistical independence approximation of the phase interferograms is usually adopted. In this paper we present a method exploiting both amplitude and phase of the interferometric images, with the purpose of expressing the multi-baseline likelihood function in closed form, and we show that, when the number of baselines increases, to achieve an higher estimation accuracy the images mutual correlation cannot be neglected. We also show that to obtain a full resolution speckle reduced intensity image from several full resolution multi-baseline interferometric (complex) images, a phase compensation and a whitening operation have to be performed before averaging the data intensities.