Research On 3D Information Extraction Technology Of Observed Target Based On CSAR Image

Circular Synthetic Aperture Radar(CSAR)imaging technology,as an emerging SAR imaging technology,uses an airborne radar platform to perform circular motions on the observation area.The antenna beam of the radar always points to a fixed imaging area,so that it can observe the observation area in all directions and can obtain more comprehensive and richer target scattering information.In addition,due to the increase in the accumulation angle of the observation azimuth,a higher resolution SAR image can be obtained,and three-dimensional imaging of the observation area can be achieved.At present,compared with the conventional SAR imaging mode,the application of CSAR imaging technology is not perfect.Especially the three-dimensional reconstruction technology of CSAR imaging observation target is less researched,and there are still many problems that need to be studied in depth.This paper has studied in depth the technology of 3D target reconstruction and building geometric parameter extraction based on CSAR imaging.The specific research content is as follows:1.The CSAR imaging principle and performance analysis is researched.First,the echo signal model of CSAR imaging is established;then,based on the established model,the spatial resolution of CSAR coherent imaging and incoherent imaging is deeply analyzed;finally,the CSAR time-domain imaging algorithm is studied.The correctness of the theoretical analysis is proved by the measured data processing results,and the imaging algorithm support provided for the elevation of the observation target and the extraction of the geometric parameters of the building later in this paper is based on the conclusions obtained.2.For the problems of low accuracy,poor stability and low algorithm efficiency of the three-dimensional imaging of the observation scene,this paper proposed a method for extracting information from the Digital Elevation Model(DEM)of the observation scene based on CSAR imaging.The characteristics of target defocus and target position offset caused by the deviation of the imaging height in the CSAR imaging process is used in the method,and the DEM information of the target is extracted through the correlation between adjacent sub-aperture images of CSAR.The extraction of the DEM information of the observation target only by flying in a single circle is realized in this method.The measured data processing results show that the proposed algorithm has the following three advantages compared with the traditional algorithm: The algorithm is more efficient,increased by more than 2.4 times,and the algorithm time consumption is reduced by more than 70%;the accuracy is higher,and the error is less than 0.1m;the robustness is better,and the root mean square error is less than 0.1m.3.For the problem of low accuracy of the extraction of building geometric parameter information based on linear SAR,this paper proposed a method for extracting geometric parameters of buildings based on CSAR imaging.The geometric structure parameters of the building is calculated by using the correspondence between the scattering characteristics of the building on the single-angle SAR image and the full-aperture CSAR image and the geometric parameters of the building in this method.At the same time,the advantages of CSAR omnidirectional imaging based on multiple angles CSAR subaperture images are used to extract geometric parameters of buildings.This method realizes the first high-precision extraction of building geometric parameters through CSAR imaging.Finally,the actual measurement data processing verifies that the proposed algorithm can extract building parameters with high precision,and the extraction accuracy can reach 1.5m.