| The space environment with the rapid development of aerospace technology is becoming more and more complex.In order to effectively detect and monitor unknown or enemy space targets,especially short-range extended targets,various space cameras have been deployed and developed,and a large number of test images are required for camera product factory testing and identification.Support,due to the limited number of measured image samples and harsh experimental conditions,the simulation of space target scene characteristics based on computer equipment can effectively solve the problem of insufficient input image data.This computer graphics rendering method based on ray tracing researches on the visible light coaxial imaging simulation technology of short-range space surface targets.The main research work includes the following aspects:In terms of the study of the characteristics of the space target,a method for describing the relative pose of the space target with the target body coordinate system as the reference coordinate system is proposed.The data structure and geometric characteristics of the target model are analyzed,and a similar merging method of bins is proposed for a complex model with a large number of bins,which reduces the number of bins by more than 50% and greatly reduces the amount of calculation.In terms of the characterization of the target surface material,a BRDF parameter model is constructed based on the measured data,which solves the problem that the physical property parameters are difficult to determine during the simulation of the target characteristics.In the construction of the space camera simulation model,a method of representing the actual optical system by using the function of the direction of the emitted light and the direction of incidence is proposed.The effect of the optical system on the imaging effect is coupled to the ray tracing process.Through the optical system parameters and the detection system The parameter setting realizes the simulation of imaging effect.At the same time,according to the principles of energy transmission and photoelectric conversion,the calculation formula of the pixel gray value in the path tracking mode is deduced to solve the problem that the imaging characteristics of the link are difficult to characterize in a complex lighting environment.In the design of ray tracing imaging simulation algorithm,an octal BVH structure simulation scene management method is adopted,and a reasonable bin division scheme is designed to avoid the erroneous division of irregular triangle bins.A method of using arrays for BVH storage and transfer is proposed to improve memory access efficiency.For camera data,an initial light preprocessing method is proposed to simplify the light generation step.In ray traversal,a simple stackless traversal method is proposed,which uses Morton coding to optimize the selection of the traversal order of child nodes,and solves the problems of insufficient GPU stack space and cumbersome stacking operations.In order to verify the correctness and effectiveness of the theoretical research and algorithm design in this paper,the imaging simulation software is designed and developed.The simulation obtains the target images under different scenarios.The simulation results show that the imaging effect and the imaging effect under different relative poses and different camera parameters Theoretical analysis is consistent.The difference between the gray value of the simulated image using the BRDF fitting function and the calculation result of the real measurement data is only about 5%.The occupancy efficiency of the octagonal BVH structure optimized by the traversal order of the child nodes is 2 times that of the general binary BVH.The traversal efficiency of the stackless traversal method is about 1.2 times that of the normal stack traversal method.The research results can provide important technical support for the demonstration of space surveillance system indicators,algorithm evaluation,performance testing,and capability enhancement. |
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