Separating and Unwrapping of Residual Topographical and Time-Series Deformation Phases in PS-InSAR Based on Zero-Temporal Baseline Combination and Time-Domain Differentiation

Abstract

To separate and unwrap the residual topographical and deformation components from the wrapped phases are the kay issues for Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) technique. The currently methods, such as grid-search method based on the assumption that the deformation in time-domain is linear, or the LAMBDA method that needs priori information to construct the pseudo-observations, etc., are still difficult to trade off accuracy against efficiency. In this paper, we propose a new method to separate and unwrap the differential phases for PS-InSAR by dividing them into residual topographical phase and differential deformation phases and performing the phase unwrapping separately. Firstly, we calculate phase ambiguities caused by residual topographical error by zerotemporal baseline combination and single parameter grid-search method. The calculated residual topographical error is used to separate the differential phases dominated by deformations from the original differential phases of PS-InSAR. Then we proposed time-domain differentiation to unwrap differential phases dominated by deformations without any assumption of deformation model in time-domain. The performance of the proposed method is tested by both simulated and real datasets. The experimental results show that, compared with classic PS-InSAR, the accuracy of residual topographical error estimation is comparable, however there is an accuracy improvement of 34.4% for the deformation parameter estimation and 35.7% for nonlinear deformation time series extraction, as well as an improvement of 20~40 times in computational efficiency.