Research On Differential Interference SAR Algorithm Based On GAMMA

Differential interferometry technology started late in China, but develops rapidly in recent three decades. With perfect and in-depth study, focus on earthquake and volcanic activity monitoring shifted to ground subsidence, landslides and other subtle surface deformation.Surface deformation is closely related to people's life,property and safety.Differential interferometry is a new convenient effective monitoring method to monitor urban surface subsidence.Compared with the traditional geodetic technology, differential interferometry technology covers a large area of work, realizing all-weather work and 24-hours work, nearly neglecting influences of rain,fog and other adverse weather. Differential interferometry technology can penetrate the clouds, smoke, snow and even vegetation to obtain the surface information which other traditional optical sensors cann't make it.Both backscatter information and phase information makes differential interferometry technology outstanding in Surface information extraction.The main contents of this paper include:1 ) The imaging principle of synthetic aperture radar (SAR) is described,and the main features of synthetic aperture radar (SAR) image are introduced.The principle of interfering phase and the principle of interference measurement in interferometry are described.2) For the algorithms involved in each stage of D-InSAR, we studied the algorithm of registration, generation of interferogram, baseline estimation, phase unwrapping and phase difference. We realized the application of D-InSAR by Two-track Method with GAMMA ,making analysis.3) For the processing methods of two differential interferometry methods, two-track method, three-track method and four-track method,the respective working processes are systematically expounded, and the results obtained by different methods are compared and analyzed. For the three-track method to obtain different group data, we focus on the efficiency of terrain pair and differential image pair in different algorithms.4) Based on the phase unwrapping principle of one-dimensional phase unwrapping and two- dimensional phase unwrapping, three kinds of phase unwrapping algorithms are studied in detail: phase unwrapping algorithm of path tracking, phase unwrapping algorithm based on minimum norm method and phase unwrapping algorithm based on network planning. Test by the unwrapping algorithm method of branching tree growth and the minimum cost stream based on triangulation is finished. An evaluation method of phase unwrapping effect based on MATLAB is proposed, and has been verified effective by experiment in BAM, applying to Las Vegas.