A new 2D/3D Phase Unwrapping Strategy of Differential Interferograms SAR

3D space-time phase unwrapping is a major problem in many disciplines including SAR interferometry, where elevation models and displacement measurements can be obtained after phase unwrapping and removing the ambiguity modulo 2 pi. The unwrapping of these phases can be performed in two different approaches, the first is to place the differential phases in the 2D plane and the second approach is to unwrap the phase taking into account the phase discontinuity in the time series. The latter quantifies the space-time deformation. In this context, we propose a strategy of 3D phase unwrapping which focuses on two methods: the first one is based on locating and tracking the unwrapping path of the best quality three-dimensional factor and the second method enables to unwrap the phase voxels regardless of the path avoiding the lines and planes cut. The proposed strategy has been tested on a series of simulated interferograms to show the use of voxel phase unwrapping 3D versus the 2D unwrapping (pixel to pixel temporally). It is then applied to the differential interferogram generated from a series of ERS1/ERS2 radar images acquired over a region of southern Algeria affected by the problem of land subsidence and the presence of scalable tectonic faults.