Research On BVH Construction Method Based On Locally-Density Clustering

With the rapid development of computer graphics and computer hardware,images rendered based on indirect illumination cannot satisfy people's pursuit of realistic images,and the real-time requirements for ray tracing based on global illumination are getting higher and higher.The bounding volume hierarchy is an important research direction of the acceleration structure in ray tracing.By means of the bounding volume hierarchy,the light intersection time can be effectively reduced and the rendering speed can be improved.Aiming at the problem of slow construction speed and low quality of traditional bounding volume hierarchy,a method of constructing bounding volume hierarchy based on local density clustering is proposed.The method is divided into primitive local density calculation,horizontal iterative clustering and vertical optimization.In the process of primitive density calculation,the scene elements are spatially sorted by Morton code,and the primitive density is approximated by local search strategy.In the initial clustering process of horizontal iterative clustering,the dense elements are selected as the cluster center.The independent scattered scene objects are segmented at the high level of the bounding volume hierarchy by clustering,the overlapping area between the high-level bounding boxes is reduced as much as possible,and the traversal efficiency is improved,then an intermediate iterative clustering step is constructed.In the vertical optimization part,the bottom-up agglomerative clustering method is combined with the surface area heuristic cost function to further optimize the construction quality,and the intermediate nodes of the K-ary tree are constructed to obtain the final bounding volume hierarchy.The experimental results show that the bounding volume hierarchy based on local density clustering improves the construction quality while ensuring the construction speed.The traversal speed is increased by 8% compared with the existing method,and the overlap is reduced by nearly 11%,which can accelerate the rendering speed of ray tracing.