Research On The Key Algorithm Of Deformation Extraction Using D-InSAR Technology

Synthetic Aperture Radar(SAR) was invented in the 1950 s. Because of its capability of all-time and all-weather imaging and through the rain, the technology has been increasingly used in military and civilian fields. Among all the applications, the important one is to extract the deformation. The technology of the Differential interferometry synthetic aperture radar(D-In SAR) uses the phase information to extract the land’s surface deformation. In recent years, D-In SAR with its advantages of rapid, all weather, all day, and the ability of high precision measurement has attracted wide attention in the field of deformation monitoring area. The information of land’s deformation using the technology of D-In SAR can be used in the seismic settlement of the surface settlement, subway, city and glacial drift, etc.In this paper, the key algorithms of the basic theories to extract the deformation information using D-In SAR are extensively studied. First of all, the applications and the research background of D-In SAR are systematically analyzed. The basic theories of In SAR and D-In SAR are summarized. Meanwhile, the process of using D-In SAR technology to extract deformation’s information and the major sources of error are analyzed. Besides, the processing process of D-In SAR, including flat-earth phase removal, phase unwrapping, the extraction of elevation information and the extraction of deformation, will be researched and analysised. Firstly, the current three algorithms of flat-earth phase removal are discussed and analyzed, including the elimination method based on orbital parameters, frequency shift method and the elimination method based on rough precision DEM data. Further, this paper gives the detailed steps to remove flat-earth phase based on frequency shift method by doing experiment. Secondly, the paper analyses the advantages and disadvantages of the current algorithms of phase unwrapping. Taking into account the different contribution of spatial noise from azimuth and distance, the paper propose a new quality map to guide phase unwrapping. At the same time, the method uses the heap sort of computer science to save time. The experimental results show that this optimization method is not only efficient, but also stable. Thirdly, the paper gives the detailed steps to simplify the geometric model. Through the specific experiments, the feasibility of this model is verified. For the extraction of deformation, the correction of deformation is introduced. Besides, the detailed steps to extract deformation information based on three-track are given. Finally, Based on the above key algorithms, the software using the technology of In SAR and D-In SAR is written in complete. Using the C++ programming language and the Qt interface environment, the software can work starting from the input of SLC formats, through the processing steps such as generating interferogram, flat-earth phase removal, image filtering, phase unwrapping, DEM reconstruction and extraction of deformation information, and form the software of In SAR and D-In SAR.