Recursive SAH-based Bounding Volume Hierarchy Construction

Advances in research on quality metrics for bounding volume hierarchies (BVHs) have shown that greedy top-down SAH builders construct BVHs with superior traversal performance despite the fact that the resulting SAH values are higher than those created by more sophisticated builders. Motivated by this observation we examine a construction algorithm that uses recursive SAH values of temporarily constructed SAH-built BVHs to guide the construction. The resulting BVHs achieve up to 28% better trace performance for primary rays and up to 24% better trace performance for secondary diffuse rays compared to standard plane sweeping without applying spatial splits. Allowing spatial splits we still achieve up to 20% resp. 19% better performance. While our approach is not suitable for real-time BVH construction, we show that the proposed algorithm has subquadratic computational complexity in the number of primitives, which renders it usable in practical applications.