Research And Implementation Of Key Technologies In Real-time Three-dimensional Roaming System

Real-time 3D roaming has been playing the important part among various researches in the field of virtual reality. As an emerging subject of information science, Real-time 3D Roaming have been widely used in military, entertainment, medical, geographic information systems, etc. This thesis'objective is to research the key technology of real-time 3D roaming, including modeling, scene organization, visibility culling, and collision detection and to implement a real-time 3D roaming demo system. The main contents are as follow:(1) Common modeling technology is discussed and their advantages and disadvantages are compared. The difference between indoor and outdoor scene organization is discussed and the indoor scene organization based on BSP-Tree is briefly introduced. The avoid triangle and object partitioning BSP-Tree building algorithm is proposed. Objects in scene are stored in leaf of BSP-Tree for visibility culling and first stage collision detection.(2) Visibility culling technologies are discussed. This paper proposed a fast cone culling algorithm based on improved BSP-Tree. Cone culling is processed based on objects that stored in BSP-Tree instead of triangles. This algorithm can fast choose objects in cone and discard the others so can rapidly reduce the objects send to Direct3D.(3) Basic theory of collision detection is introduced and a double stage collision detection algorithm base on space division and surrounding ball was used to accelerate the speed. First we choose the smallest sub space and detect collision based on objects' surrounding ball and then do accurate collision detection using object's triangles. This paper finally builds an indoor scene using 3DS MAX and implements a real-time 3D roaming demo system using VC2005 and Direct3D. The cone culling algorithm and collision detection algorithm we proposed is improved to be effective.