Performance Analysis Of Tomography SAR Point Cloud Generation Algorithm And Verificatio

With the promoted of urbanization in China,the construction speed of smart cities and digital cities is getting faster and faster.Among them,the acquisition of three-dimensional information of cities is an indispensable part.The three-dimensional reconstruction of urban buildings is currently the main means of obtaining urban three-dimensional environment.Oblique photogrammetry and Lidar are two kinds of technologies that are currently widely used in the three-dimensional reconstruction of building.The main application scenarios of these two technologies are the modeling of large range urban buildings and the fine modeling of small-scale independent buildings respectively.The two technologies collect data in a tedious way,Its access to city information is not timely and easily affected by climatic conditions.Although the traditional synthetic aperture radar imaging technology can overcome these problems,because of the limitation of microwave imaging principle,only two-dimensional imaging can be performed,which is lack of resolution to the altitude.This technology is a further extension of the traditional InSAR technology.Its main feature is to form a large aperture in the height range to achieve the three-dimensional imaging effect of the target scene by constructing multiple baselines in the direction perpendicular to the line of sight.This paper focuses on the core technology of tomographic SAR imaging,mainly focusing on the tomographic focus algorithm of tomographic SAR and the verification of the accuracy of building point cloud generated by imaging.The main work of this paper is as follows:(1)Explain the basic principle of three-dimensional tomography in tomography.The basic principle of InSAR imaging is summarized,and the principle of tomography imaging is further extended based on the characteristics of InSAR imaging.(2)Studying the algorithm of tomographic SAR altitude-focusing.The tomography SAR imaging process can be divided into two-dimensional imaging and t altitude-focusing,This section first analyzes existing tomography SAR imaging algorithms including Fourier transform focusing algorithms and frequency spectrum estimation algorithms,According to the defects of these two algorithms,the theory of compressing the tomographic signal using the compressive sensing algorithm to obtain the building height information is proposed.Firstly,the basic principle of compressed sensing is expounded,and then the application of compressed sensing algorithm in altitude-focusing is analyzed in combination with the basic principle of tomography SAR.(3)Through two-dimensional and three-dimensional simulation experiments,the performance of the algorithm is analyzed and compared under different baseline spacing conditions,and a gradient descent sparse reconstruction method is proposed to perform high-intensity signal reconstruction.The imaging performance can be obtained through comparative analysis of experiments and is better than iterative threshold algorithm.(4)Studying the Point cloud generation of urban building based on Tomography SAR.By focusing on the tomography signals of the urban buildings and obtaining the altitude information and the three-dimensional point cloud can be obtained.Though selecting the Water Cube from the Beijing area 28 TerraSAR-X rail lift data and 41Comos-skymed data as the object of study experiment,succeeded in obtaining the 3D point cloud of target building,and verified the applicability and effectiveness of the method proposed in this paper.(5)The accuracy of the point cloud obtained by tomography SAR technology can be verified by densely-built point clouds obtained by terrestrial lidar.By segmenting the point clouds obtained by terrestrial lidar and Tomography SAR into different facade,and then extracting the boundary of the facades one by one.Lidar's three-dimensional point cloud data is used as a benchmark to compare their geometric features.thereby verifying the accuracy of3 D Point Clouds reconstruct by Tomography SAR.Though selecting the Pangu Seven Stars Hotel as the object and verified the applicability and effectiveness of the method proposed in this paper.