Research On The Key Technology Of Roaming In Multi-viewpoint VR Environment

Virtual reality which has played a significant role in medicine, teaching, entertainment, industrial production, geographical exploration and military training, is an important branch of the current computer simulation technology. The virtual roaming is one of the most important applications of VR. With the continuous development of roaming technology and the advancement of user's requirements, the scale of the virtual scence, the simulation accuracy and real-time interaction on virtual system have been required higher qualities. This thesis deeply investigates the virtual roaming technology in large-scale virtual scence behind the application background of the simulated training environment, and acquires the following results:1. The key technologies of virtual space construction are analyzed. A virtual system is generated by using cylindrical panoramic and chain-space.2. A multi-view-based virtual space navigation system is designed. It is composed of scene database generation and roaming engine functional modules, and optimized by using the level of details technology. Efficiency of the system is greatly improved by the separate structural design and function calls between modules.3. A fast vector-based collision detection algorithm is proposed. By combining the phase factors and the directional loop, the algorithm detects the collision between view-points and triangles by means of vector calculations. Because the completed cosine calculations is avoided, the algorithm only needs one cross product operation and one comparison operation to complete the test in the best case.4. A space chain based on quadratic spline interpolation is designed and implemented. The space chain is generated in real-time according to the coordinates of the adjacent view-points. Then the interpolation nodes are settled and the node images are accessed by using the curve function parameter t. By adopting this technology, the shortage that the linear-chain-space can not realistically simulate the user to bypass the convex edge of the structure of large obstacles to see the scenes behind of it, is solved and the smooth roaming among multi-view points is achieved.