The Near-earth Space Environment, 3d Modeling And Visualization Technology

The simulation for the real outer space plays an important role in human being's space flight activities. Being a key technology of the real outer space simulation, 3D modeling and visualization of the near earth space environment (NESE) is a frontier research area. In this thesis, some main issues are researched and some significant results are achieved. The major work implemented is presented as follows:1. Preliminary Research on 3D Modeling and Rendering of Key Elements in NESE.(1) A new method for star field simulation is presented in accordance with the human's observing experience. The stars are rendered in the different sizes and colors in form of point or billboard, which is determined by their magnitude; the distance conception is introduced for the stars, and the stars data are organized by octree for real-time high-speed visibility judgment.(2) A earth LOD model based on the ellipsoid is implemented, and a continual global terrain LOD algorithm called SROAM is given base on ROAM.(3) The algorithms of equivalence face and volume rendering for the space environment elements visualization are addressed, and an efficient method to achieve atmosphere effect is presented base on the hardware. This algorithm avoids complicate physical computation.(4) An new geometry and behavior integrated model language(GBML) for space object is designed to settle the problem on the parameter description of the model's geometry and behavior, and then a model reading and display COM compoent for GBML is developed.2. Designs and Implementations on an General 3D Engine for NESE Visualization —NESE-3D.(1) Multiple elimination algorithm are integrated together to ensure the real-time property for 3D rendering of the engine, which include the back-face elimination, the view frustum culling, the earth occlusion culling, and the screen space culling.(2) A special objects control technology is adopted in the engine. And a continual view point switch algorithm based on the spherical linear interpolation (SLERP) is presented to achieve fluency in camera sight changing.(3) The engine's script description is designed , and the difficulties in implementing the script control technology is solved.3. The Distributed NESE (DNESE) based on HLA is realized.4. At last, a NESE 3D Simulation Demo Platform (Space Eye 2005) is founded, with power function, sound effect and stable performance.