Research On Basic Theory And Algorithms Of InSAR For The Earth's Surface Deformation Measurement

Synthetic aperture radar interferometry (InSAR) firstly proposed by Graham is a new imaging technique for earth observation. Since this new technique can acquire information independently of meteorological conditions and sun illumination and possesses characteristics of measuring the earth quantificationally with high accuracy, it is becoming a very important tool for earth observation and geophysical research. InSAR geodetic technique can calculate the topography of a surface and its changes over time by exploiting the phase differences exited in an interferogram formed by at least two complex-valued SAR images acquired from different orbit position and/or at different times. In fact, the interferogram is in essence the contour map of the change in distance between the ground and SAR instrument. Therefore, the key points inside InSAR technique are two basic problems: how to acquire a high quality interferogram and how to extract the information about topography and land deformation from this interferogram.This project aims at theses basic problems, and launches a systemic and all-around research work about basic theory and data processing algorithms of InSAR land deformation measurement techniques. Some main works include:(1) SAR data imaging and SAR image geometrical processing are very basic for InSAR data analysis, therefore the basic theory and algorithms about SAR imaging and SAR image geometrical correction, and a foundation is lay for further research. At the same time, we apply theses algorithms on the SAR raw data acquired at Huanghe delta area, and get a good imaging effect.(2) Based on analysis about the basic theory of InSAR, the flowchart for InSAR data processing is discussed, and the coregistration algorithm which can influence the quality of interferogram and the phase unwrapping algorithm which is very important for extracting information from the interferogram are further investigated. We also choose SAR data about some typical areas to do InSAR data processing work and acquire some high quality interferograms.(3) The basic principle of differential InSAR (D-InSAR) is discussed in detail, and the D-InSAR data processing flowcharts for two-pass and three-pass respectively are further investigated, especially the effects posed by deccorelation and atmosphere are analyzed quantificationally. We also discussed the temporal decorrelation problem integrating with real SAR data.(4) The flowchart for permanent scatterers InSAR (PS-InSAR) data processing is carefully studied based upon detailed analysis about the basic principle of PS-InSAR. An algorithm for PS identified from SAR data is investigated in detail by SAR image time series analysis. The data structure for saving large quantities of irregular PSs in computer memory is discussed and a graph structure is proposed for this purpose.(5) an algorithm based on periodgram and spectrum analysis is introduced to solve multi-baseline phase unwrapping problem about each PS. Deformation inverse techniques for PS are carefully discussed aim at linear and non-linear deformation models respectively.By these research works, not only some preconditions for setting up a platform to do basic theory and application research work are created, but also a foundation is laid for further research about key InSAR techniques.