Research On Imaging And Detection Technology In SAR Tomography

With the increasing demand for three-dimensional(distance-azimuth-height)and four-dimensional(distance-azimuth-height-deformation)information in terrain mapping,sedimentation inversion,deformation detection,vegetation estimation and so on,traditional SAR two-dimensional imaging has been unable to meet the application requirements.SAR tomography utilizes a plurality of SAR two-dimensional complex images acquired in the same region,and has a three-dimensional imaging capability for measuring the target height information by forming a synthetic aperture at a height perpendicular to the distance-azimuth plane.When multiple SAR images used by it are obtained in a longer time series,it can be considered that the SAR tomography also forms a synthetic aperture in time so that the information of the target along the height to the linear deformation rate can be obtained and then,it has four-dimensional imaging capability.SAR tomography has been widely used in many fields such as geography,geology,biology and ecology because of its unique three-dimensional and four-dimensional high-resolution imaging capabilities,which has been widely focused and studied at home and abroad.But at the same time,SAR tomography technology is also facing some key issues,mainly is how to achieve a more robust,efficient,high-precision target imaging and testing.Because many of the SAR images used in current SAR tomography are obtained in larger time spans,many targets become irrelated,so the focus in SAR tomography is that those permanent scatterer that maintains good coherence along the images.And these scatterers are sparse at each distance-azimuth resolution unit.How to accurately determine the number of permanent scatterers in each resolution unit and the high accuracy parameter estimation for each scatterer is the core problem of SAR tomography and detection.Based on this idea,this paper first describes the principle of SAR tomography and detection,and analyzes and compares the existing methods.Then,this paper studies the application of beamforming algorithm,relax algorithm and Compressive sensing algorithm in SAR tomography,and combines the generalized likelihood ratio test method with SAR tomography to propose SAR layer based on the above three algorithms And the three methods are analyzed and demonstrated from the theoretical level,the simulation level and the real data layer.