Research On Imaging Technology Of DEM In Radar Simulator

Due to the influence of location,climate and other factors,it is hard to use real radar to teach sailors.The use of radar simulators for practical training is a viable means.As the source of radar simulation image,DEM has the advantages of high precision,flexible application and can be used to construct 3D terrain.The thesis conducts an in-depth study of DEM and combines the radar cross section(RCS)model and computer simulation technology.The main results are as follows:(1)In view of the characteristics of DEM,the processing methods of DEM are studied from the aspects of data fusion,sampling and interpolation,file splicing,file segmentation and index.The data of electronic chart and artificial building information are integrated into the DEM,which lays a foundation for the modeling of RCS;the merits and demerits of three kinds of interpolation methods are analyzed experimentally to meet the needs of different sampling accuracy;the splicing method of scattered DEM block is introduced;a quadtree-based file segmentation and indexing algorithm is proposed to facilitate the use of subsequent data files.(2)Based on the DEM,the RCS calculation methods for different types of targets are studied.For artificial buildings,the improved Gordon method and the high-order parabola equation method are used for the RCS calculation of large and small targets,respectively,and the experimental results are verified;for the natural terrain,the RCS calculation method based on the small-plane element model is introduced,this method can obtain more realistic results by using the statistical terrain topography factor;according to the characteristics of DEM,a ground echo intensity calculation formula is proposed,by means of statistical elevation distribution probability and artificial fitting of parameter variation curve,the difference of echo intensity of target is highlighted.(3)The radar image is simulated with RCS as the main factor affecting the target echo intensity.Before the simulation,the RCS pre-calculation method is proposed,and the data structure of RCS storage and retrieval is designed to reduce the real-time computation;in the simulation,the method of scanline solving is improved to solve the problem of pixel repetition and omission;after simulation,an image filling algorithm based on KNN is proposed to optimize the image quality in view of the error of image calculation.The contour of the shorelines of the final image are basically consistent with the satellite image,the targets are correct and the simulation works well,proved the feasibility of generating radar simulation images from DEM.The research results have been successfully applied to a certain type of marine radar simulator.