Comparison And Evaluation Of InSAR Phase Unwrapping Algorithm

SAR Interferometry (InSAR) is a new potential technology of satellite application, which have very wide application fields and practical value. However, there are still some key techniques needed to be studied. Phase unwrapping is a key step and the most significant error source. Phase unwrapping is indispensable for the purpose of either creating digital elevation model (DEM) or extracting surface deformation information with the InSAR approach. The achieved accuracy level of DEM or deformation measurements is highly dependent on the accuracy in the unwrapped phases.Firstly, this paper introduces the principle, the main steps and the key techniques of the data processing of InSAR and D-InSAR, and then phase unwrapping is elicited. Secondly, brunch-cut algorithm, quality guided algorithm, mask-cut algorithm, Flyn algorithm, iterative least-square algorithm, unweighted least-square phase unwrapping by means of multigrid algorithm, least-square phase unwrapping by means of FFT and PCG algorithm are introduced detailedly. Then, this paper categorizes some of the phase unwrapping methods—path-following algorithm, least-square algorithm and network-flow algorithm, discusses the core idea of those algorithms at the same time. Based on test data and Xi'an data this paper runs most of those algorithms, then compares those algorithms by six aspects: (1) wrapped phase map after unwrapping, (2) formula, (3) comparison to branch-cut algorithm, (4) discontinuity map, (5) combined map, (6) run time. By summarizes the phase unwrapping algorithms, this paper puts forward the integrating algorithm.At last, this paper presents applicability of the phase unwrapping algorithms, dis- cusses how to define the evaluation criterion, then discusses the future areas of phase unwrapping.