Simulation of space-based visible surveillance images for space surveillance

The simulation of space-based visible surveillance images can offer technical support to the index argumentation, scheme design and ground-tests of spatial optical system. Based on the analysis of the space-based visible surveillance principle, this paper establishes the simulation framework of space-based visible surveillance images, as well as its workflow, and simulates the images of the celestial background and space objects respectively with OpenGL. Firstly, concerning its visual features, the celestial background can be divided into point objects and surface objects. The rendering methods based on OpenGL for both objects are given and the basic space background rendering workflow is also established. The 14-magnitude stars are rendered in the simulation of celestial background which can satisfy the need of the space-based visible surveillance. Secondly, this paper calculates the orbital elements of the objects through utilizing TLE data and SGP4/SDP4 model and obtains the positions of them in the CCD through coordinate transformation. Simultaneously, the brightness model is built up in combination with the distribution features of the space objects' surface and the simulation of the space objects' images is realized with the attainment of the brightness in the CCD through greyscale conversion. Finally, the space-based visible surveillance images are generated by overlapping the star background and the objects' images. The fidelity of the simulation images is almost identical to the images which are obtained by the SBV camera, which convincingly proves that the proposed rendering method can effectively simulate the celestial background and the target images when observed with space-based visible camera.