Distributed visibility culling technique for complex scene rendering

摘要

This paper describes a complex scene rendering system that it can comprehensively render larger and more complex 3D scenes in a form of output-sensitive way by means of using distributed visibility culling technique. The process of the proposed visibility calculations is explicitly divided into two distinct phases, one is preprocessing stage, and the other is on-the-fly stage. At the preprocessing stage, the whole scene is partitioned into numerous regions, namely spatial cells, by adopting BSP tree algorithm. Accordingly, the complexity weight of each cell is estimated in advance depending on the number of geometric polygons within the cell. Afterwards we find out possible occluders in each cell for accelerating the real-time occlusion culling at run time. Moreover, instant visibility is taken into account to quickly calculate the tight potentially visible set (PVS) which is valid for several frames during the on-the-fly phase. As dynamic load balancing algorithm is concerned, we employ the cell arrangement mechanism to dynamically assign a specific amount of service demand to each calculating machine. The amount of service demand is estimated when a calculating machine is dynamically inserted into or removed from the distributed calculating cluster. Finally, after the drawing machines gather the PVS results from every calculating machine, they render the scene for users to view it on the next frames. From the simulation results, we can see that the proposed real-time walkthrough environment takes good advantage of the distributed visibility culling technique for displaying large, complex 3D scenes in real time and gets rid of a troublesome computation delay problem.