A METHOD OF FILTERING AND UNWRAPPING SAR INTERFEROMETRIC PHASE BASED ON NONLINEAR PHASE MODEL

This paper presents a new e-cient algorithm of flltering and unwrapping phase images for interferometric synthetic aperture radar (InSAR) based on nonlinear phase model. First, we analyzed the statistical and signal properties of interferometric phase, and proposed the concept of nonlinear phase model. The model of re∞ecting topographic contour is used to approximate the interferometric phase variation occuring over the local window. And the lower amplitude bound of the principal vector is decided and the value solution method is given, which can solve efiectively and adaptively the nonlinear factor of the phase. Second, we studied the application of nonlinear phase model in interferometric phase flltering. When compared with other advanced fllters, the nonlinear phase compensation fllter, with a higher computation e-ciency and a better phase estimation accuracy in low coherence areas, has a stronger ability to reduce interferometric phase noise in rugged terrain. Finally, we introduced the nonlinear phase model to phase unwrapping, which increased the reliability of integration path and the accuracy of the phase gradient, and improved efiectively the performance of phase unwrapping. And the real data processing results demonstrated the validity of the proposed nonlinear phase model and of the corresponding solutions.