Ray Tracing, Bounding Volume Hierarchy, Bvh, Axis Aligned, Tetrahedron Octahedron.
illustrations show the potential behind this concept: Using a more versatile and intelligent BVH construction for AABT. Note the additional (-x+y) axis to allow for another diagonal split. While the root node bounding volume is most likely more loose than an AABB, we see tighter child volumes