Research On Partial Technique Of 3D Scene Walkthrough

3D scene walkthrough means users can interact with real or virtual 3D scene environment which is indicated on the screen by some equipment. This operation can be used to simulate the man's walkthrough in real environment. Scene walkthrough is very important in the field of VR, and has a broad horizonand bright prospect for development.In this thesis, by having a thorough knowledge of relative theory of VR and scene walkthrough, the former research is dissected in this direction and then several key techniqies involved in 3D scene walkthrough are studied in depth. These techniqies include LOD (Level of Detail) simplifying scene, collision detection when moving and path planning for automated walkthrough.Virtual environment always means a mass of data. Because of this problem, the computing-power of computers can not meet the needs of real-time rendering scene. In such cases the LOD is used to improve real-time scene display. On the basis of regular net model, a LOD algorithm based on improved quadtree-split and node storage is introduced. In order to expedite the speed of quadtree generation, the times of error judgment is dwindled down. And at the same time, a new node storage structure means much less redundant data can be stored than traditional way.And besides, in order to simulate the real world best, the problem of collision should be solved at the walkthrough time in 3D scene. A collision detection algorithm based on mixed hierarchical bounding volumes is proposed. And lots of objects which don't collide with each other are excluded quickly. It reduces the complexity of detection to a certain extent. By the characteristic of data structure in this thesis, insertion sort is used and improved in the algorithm. It can reduce the consumptive of time.Finally, for interactive walkthrough and automated walkthrough these two ways in 3D scene, the implementation method of interactive walkthrough is analysed simply, and after that automated walkthrough is researched in detail. In accordance with the peculiarity of 3D scene walkthrough researched in this thesis, obstacles having three dimensions project some shadows on two-dimensional. Then path planning is implemented on two-dimensional. The method of predecessor basis on three dimensions is improved and used in this thesis. So it is suitable for the 3D scene discussed in this thesis. At the same time the ratio-nality of path also can be thought.