SOBB: Skewed Oriented Bounding Boxes for Ray Tracing

Abstract We propose skewed oriented bounding boxes (SOBB) as a novel bounding primitive for accelerating the calculation of ray‐scene intersections. SOBBs have the same memory footprint as the well‐known oriented bounding boxes (OBB) and can be used with a similar ray intersection algorithm. We propose an efficient algorithm for constructing a BVH with SOBBs, using a transformation from a standard BVH built for axis‐aligned bounding boxes (AABB). We use discrete orientation polytopes as a temporary bounding representation to find tightly fitting SOBBs. Additionally, we propose a compression scheme for SOBBs that makes their memory requirements comparable to those of AABBs. For secondary rays, the SOBB BVH provides a ray tracing speedup of 1.0‐11.0x over the AABB BVH and it is 1.1x faster than the OBB BVH on average. The transformation of AABB BVH to SOBB BVH is, on average, 2.6x faster than the ditetrahedron‐based AABB BVH to OBB BVH transformation.