Research On High Precision InSAR Imaging And Processing Method

Interferometric synthetic aperture radar(InSAR) can measure large area terrain in all-time and all-weather and obtain the 3D terrain by elevation inversion. This paper mainly researchs the methods of InSAR Surface Back-Projection imaging and elevation inversion and the imaging and elevation inversion methods based on time varying baseline. The work and innovation of this paper are as follows:(1) The InSAR imaging algorithm based on Surface Back-Projection is researched. First, the steps of flat Back-Projection imaging are introduced. According to the problems of flat Bace-Projection, such as interferometric phase information loss and terrain distortion of elevation inversion, this paper analyses the model of Surface Back-Projection and deducts the Surface Back-Projection imaging can reduce the interferometric phase information loss and the numbers of interferometric frings. So it can improve the precision of elevation inversion. This paper also proves that the closer the imaging space and original terrain are, the higher the precision of interferometric phase and terrain elevation is. Finally, the simulation proves that Surface Back-Projection algorithm can improve the precision of interferometric phase and elevation inversion compared to flat Back-Projection imaging algorithm.(2) The iterative Surface Back-Projection imaging and elevation invertion algorithm is proposed. For traditional elevation invertion method has low precision and the problem of terrain distortion, this paper proposes iterative Surface Back-Projection imaging and elevation invertion algorithm. According to the advantage of Surface Back-Projection imaging that the closer the imaging space and original terrain are, the higher the interferometric phase precision and terrain elevation precision are, the algorithm images and compensates terrain elevation iteratively to improve the precision of elevation inversion. At last, the simulations prove that iterative imaging and elevation invertion algorithm can improve the precision of terrain elevation obviously no matter the terrain is simple or complex. Compared to the traditional method of elevation invertion, this algorithm has higher precision.(3) The InSAR imaging and elevation inversion algorithms of nonlinear line motion are researched. First, this paper analyses the influences on interferometric phase extraction and elevation inversion when the flatform trajectory changs. The paper proves that flatform trajectory error can cause obvious interferometric phase error and can barely affect elevation inversion. Then the simulation proves that Back-Projection imaging algorithm can compensate interferometric phase error to get high precision interferometric phase and the elevation inversion precision is also very high by comparing to the situation that platform moves in straight line. Then this paper analyses the influences on interferometric phase extraction and elevation inversion when the baseline obliquity changes and proves that interferometric phase has obvious error and elevation inversion precision will be worse when baseline obliquity is changing. This paper compensates the elevation inversion error caused by baseline obliquity changing through using corresponding baseline obliquity to invert elevation at every azimuth moment. In the end, the simulation proves that the method can obviously improve the elevation inversion precision when baseline obliquity changs compared to the elevation inversion method with regular baseline paremeters.