Study On Three-dimensional Grid Modeling And Optical Characteristics Calculating Methods Of Space Target

In the researching process of the detection, feature extraction, identification and tracking technology for space target, optical characteristics of space target, as one of the most important information sources, is urgently needed for solving the key technologies such as the simulation and verification of target recognition and tracking algorithms, the feasibility analysis of optical sensor, the determination of parameters, and so on.In this paper, the optical characteristics calculation methods of space target are researched based on three-dimensional geometric modelling and grid modeling of space target. The geometric model, grid model, and optical characteristics calculation model of space target are built up, and finally the accurate calculation of optical characteristics is realized.First of all, on the aspect of the geometric modelling for space target, the most popular data exchange standard——IGES (Initial Graphics Exchange Specification) in CAD/CAM field is taken in this paper. Based on the study of the structures and reading technique of IGES file, the three-dimensional gerometric modelling is realized taking used of OpenGL (Open Graphics Library) technique in the Visual C++6.0 development environment.Secondly, on the basis of the established three-dimensional gerometric model, three kinds of target surface shapes including analytic geometry surface, two-dimensional plane/curved surface and three-dimensional parametric surface, which are the most common shapes of the target surface, are analysed. Several kinds of methods are taken to realize the grid. The structured grid model, Delaunay triangulation grid model and AFT (Advancing Front Technique) model are established, and then the grids of space target with complex construction are accomplished.Thirdly, on the aspect of the optical characteristics calculation model for space target, three optical characteristics calculation models, including theoretical model, finite element model, Monte Carlo ray tracing model, are analyzed in this paper, the theoretical basis and key algorithms of them are detailed studyed. Combined with geometrical structure model and grid model of sapce target, the optical characteristics calculation of space target is accomplished.Finally, the software calculating the optical characteristics of space target is compiled taking used of the OpenGL technique in Visual C++6.0 development environment. The GUI of the software has the good ability of man-machine interaction. The calculation experiments are done using this software. Taken the accuracy, computational precision, calculation time complexity of the optical characteristics models as the key factor, the combination properties of the models are analyzed.