Study On Phase Unwrapping Method For InSAR&D-InSAR

SAR Interferometry (InSAR) and Differential SAR Interferometry (D-lnSAR) are new potential technologies 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 one of the key step among the lnSAR& D-lnSAR processing. Its accuracy directly affects the precision of the DEM and deformation that derived by InSAR and D-lnSAR.Firstly, this paper introduces the principle, the main steps and the key techniques of the data processing of InSAR and D-lnSAR. Secondly, two main kinds of phase unwrapping methods (path-following method and least-square method) have been discussed in this paper. In addition, the author comparatively analyzed these theories and properties with real experiment. Base on these analysis, a generalized phase unwrapping approach are introduced that phase unwrapping can be regarded as a problem of constrained optimization. There are two parts of it. One is to define an effective optimization objective function, and the other is to select an efficient calculation algorithm. According to this approach, a statistically based cost function through which phase unwrapping is treated as a maximum a posteriori probability (MAP) estimation problem is defined. On the other hand, considering the unwrapping is NP-hard problem, the network-flow algorithm is present to solve this problem. The experiment results show that the Statistical-Cost Network-Flow method has gained a more accuracy result than other existing algorithm's results. Finally, the author describes the basic steps of D-lnSAR processing and the preliminary results in monitoring of city subsidence.