Three dimensional SAR image focusing from non-uniform samples

Multiple SAR signals acquired along different orbits can be exploited for reconstructing a three dimensional (3-D) reflectivity profile of the scene along azimuth, range and elevation co-ordinates. For the 3-D image formation, the problem of the non-uniform spacing of the orbits has to be considered. In this paper we propose a technique based on two steps: 1) a preprocessing step, in which the samples of the multi-pass signal is computed on a grid which is uniform in the elevation direction, starting from its unevenly spaced samples; 2) a 3-D image focusing based on a simple 3-D convolution operator. The technique proposed has the main advantages of preserving numerical efficiency and allowing to easily include information on the signals bandwidth in the pre-processing step, in such a way to regularize the problem and obtain stable solutions.