A filtering approach to improve deformation accuracy using large baseline, low coherence DInSAR phase images

Phase noise in an interferogram hinders the accuracy and reliability of interferometric synthetic aperture radar (InSAR) measurements, including deformation estimation and topographic mapping. The Goldstein filter is one of the most commonly used interferogram filters to reduce the effects of phase noise. In this paper, we present a modification to the Goldstein interferogram filter such that the maximum value for the filtering parameter alpha is set to greater than 1 over less coherent areas so that aggressive filtering is implemented on incoherent areas. We also discuss the combined use of estimated coherences from linear and non-linear filters to deal with the coherence saturation due to the strong filtering, which is crucial in generating InSAR deformation products.