Weighted multi-resolution phase-unwrapping method

The proposed method for phase unwrapping is based on a global analysis of the interferometrical phase. The underlying principle is that the interferogram is partitioned such that the unwrapped-phase function on each element can be locally modelled by the mean values of the phase difference between neighbouring pixels in azimuth and range directions. Using this local information and a least-squares algorithm (Gauss-Seidel relaxation), an approximate model of the unwrapped phase is then generated and tested by calculating the "residue image" defined as the difference between the original interferogram and the model itself. If there are residual fringes, then the result must be iteratively refined applying the method to the residue image. The accuracy of the proposed estimation depends on the dimensions of the elements and the dynamic content of the phase, i.e. on the "roughness" of the ground surface. In order to limit the influence of noise and layover on the unwrapped-phase function generation, we are working to a "weighted" version of our algorithm. This approach introduces for each element of the partition a coefficient of confidence representing the reliability of local slope estimation.