Automatic Creation of Object Hierarchies for Ray Tracing of Dynamic Scenes

Ray tracing acceleration techniques most often consider only static scenes, neglecting the processing time needed to build the acceleration data structure. With the development of interactive ray tracing systems, this reconstruction time becomes a serious bottleneck if concerned with dynamic scenes. In this paper, we describe two strategies for efficient updating of bounding volume hierarchies (BVH) for scenarios with arbitrarily moving objects. The first exploits spatial locality in the object distribution for faster reinsertion of the moved objects. The second allows insertion and deletion of objects at almost constant time by using a hybrid system, which combines benefits from both spatial subdivision and BVHs. Depending on the number of moving objects, our algorithms adjust a dynamic BVH six to one hundred times faster than it would take to rebuild the complete hierarchy, while rendering times of the resulting hierarchy remain almost untouched.