Research On The Reality Issues Of Virtual Environment Generation Based On Scene Graph System

Virtual Environment generation is the essential element for the application of virtual reality, which has two basic demands, the quality of real time and reality. Even though the rapid enhancements have been made for the performance of the graphic hardware, some compromise must be made between the demanding for the real time and reality of virtual environment. In the field of Virtual Environment generation, scene graph system in the retained mode has actually become the leading scheme. The main research purpose of this thesis is in the precondition of guaranteeing the real time simulation, improving the quality of reality of the virtual environment as much as possible based on scene graph system.The main contents of this thesis include the research on illumination reality and the motion reality, which are the key issues of Virtual Environment generation. To solve the former, this thesis divides it into two sub-problems, one of which focuses on the research of how to get the better vision appearance in scene graph system by using the per-pixel rendering technique based on the programmable graphics processor to make real-time rendering, and the other of which concerns the research of how to creating the real-time high-quality dynamic shadow effect in virtual environment. To solve the latter, the motion reality of virtual environment, this thesis mainly discusses the problem of how to make the rigid body dynamics modeling in virtual environment for scene graph system, which ensures the consistency of the motion in the virtual environment.The important innovation of this thesis includes:1) A new type of programmable shader node for general scene graph system is put forward and a real-time per-pixel lighting method based on the design of the programmable graphics hardware is implemented, which makes up the shortage of scene graph system for the traditional per-vertex lighting, then improves the appearance of the slippery surfaces in the virtual environment very much.2) By using the per-pixel lighting technique put forward in this thesis and improving the standard local illumination mode, an enhanced real-time bump mapping method based on the normal map is realized in scene graph system, which improves the expression for the coarse surfaces in the virtual environment based on general scene graph system.3) Careful research has been done for the real-time shadow algorithms, especially for the shadow algorithms of image space. And aiming at the real problems of real-time dynamic shadow creating in virtual environment, a set of integrated real-time shadow creating method for scene graph system is put forward and realized, by improving and optimizing the light space perspective shadow algorithm, which may be applied with the per-pixel lighting technique and can improve the quality of lighting reality very much.4) Inspired by the scene graph technology, the research on the rigid body dynamics modeling for general scene graph system is done. A real-time rigid body dynamics simulation framework for general scene graph system is put forward and realized in modules using open dynamics engine, which solves the simulation problems of rigid body in virtual environment based on scene graph system.