Least squares unwrapping with iterative corrections

An approach for least squares unwrapping (LSU) with iterative corrections and its application on several data sets is presented. The LSU-program, used is this work, was implemented after the algorithm proposed in D.C. Ghilglia et al. (1994). LSU solutions are generally distorted because of undetected erroneous phase values, R. Bamler et al. The distortions become visible in the error interferogram, that is the difference between input phase and rewrapped absolute phase. The concept of this method is to unwrap the error phase in an iterative way using thresholds on the phase gradients. Addition of the unwrapped error-phase to the distorted solution yields a corrected solution. A ERS-1/ERS-2 Tandem interferogram of the Italian Alps is used to illustrate the performance of the method.