On fast construction of SAH-based bounding volume hierarchies

With ray traversal performance reaching the point where real-time ray tracing becomes practical, ray tracing research is now shifting away from faster traversal, and towards the question what has to be done to use it in truly interactive applications such as games. Such applications are problematic because when geometry changes every frame, the ray tracer's internal index data structures are no longer valid. Fully rebuilding all data structures every frame is the most general approach to handling changing geometry, but was long considered impractical except for grid-based grid based ray tracers, trivial scenes, or reduced quality of the index structure. In this paper, we investigate how some of the fast, approximate construction techniques that have recently been proposed for kd-trees can also be applied to bounding volume hierarchies (BVHs). We argue that these work even better for BVHs than they do for kd-trees, and demonstrate that when using those techniques, BVHs can be rebuilt up to 10x faster than competing kd-tree based techniques.