| The development of human space activities has prompted the rapid development of related technologies such as space operations and space exploration.As an important type of space operation,escort missions have put forward an urgent need for space target imaging simulation.Space target imaging simulation is a complex system simulation problem involving multi-disciplinary and multi-technical fields.Researchers at home and abroad have developed a variety of simulation systems based on Open GL,ray tracing and other methods.Among them,the PBRT renderer based on the efficient ray tracing algorithm supports the access of the remote sensing physical model.While ensuring the simulation accuracy,it shortens the development cycle and reduces the development cost,and has strong application potential in space target imaging simulation.This paper takes it,the requirements of space target imaging for accompanying mission,as the application background.What has been carried out based on the PBRT renderer is the research on multispectral imaging simulation technology of space accompanying flight targets.On the basis of the construction of a space target scene,to solve the question that the inconsistency between the simulated images based on the chromaticity system of PBRT and the output results of spatial optics/multispectral cameras.A method has been proposed that multispectral imaging simulation based on detector spectral response and the space companion target imaging simulation system has been developed.Then the paper verifies and analyses the simulation result.The following three contents are the main research work of the paper included:(1)The spatial target scene construction has been completed.The target and the light source are the main objective components of the space scene.It has built a space target model that meets the needs of optical spectrum observation through joint modeling of geometric features and optical characteristics;It has established a light source model dominated by the sun;It has clarified the scene coordinate system and observation coordinate system,and has completed the conversion of each coordinate system,which can accurately represent the positional relationship of target,light source and observation camera in space.(2)A space target multispectral imaging simulation method based on detector spectral response has been proposed.Based on the imaging simulation process of PBRT renderer,the spectral characteristics of material and the spectral response characteristics of optical camera were introduced,and it modified the output mode which based on human eye chromaticity system,and set up a model based on the spectral response of detector,so the multispectral imaging simulation was realized based on PBRT renderer.On this basis,a camera special effect model was established for the special imaging effects that may occur in space,and a more realistic simulation effect could be obtained.(3)The imaging simulation system of space accompanying flight targets has been developed.The simulation module,simulation process and system interface have been designed,and several sets of experiments have been carried out by configuring simulation parameters.Those verifies the simulation capability of the system which are different camera parameters,different image synthesis methods and simulation image sequences based on orbit parameters have been obtained respectively.At the same time,the simulation efficiency has been improved by modifying the storage method of the radiance value and the image output method.Based on the real-time optical camera images obtained in the real space accompanying mission,the quantitative evaluation of the consistency between the simulated image and the satellite image was carried out,and obtained the 95.78% of the radiation consistency,97.54% of the resolution similarity,and 96.93% of the geometric distortion similarity.The validity and accuracy of the simulation results have been verified.The above research work can provide a simulated image source for image processing algorithms such as target recognition in space operation tasks such as accompanying flight,and provide technical support for the optimal design and demonstration and evaluation of space imaging systems. |
