Spatial splits in bounding volume hierarchies

Figure 1: Sample scene consisting of roughly 1.9 million triangles (left). Our method (middle) results in a significant reduction of ray shooting costs compared to a regular bounding volume hierarchy (right). The heat views visualize the summed number of traversal steps and primitive intersections for primary rays. Bounding volume hierarchies (BVH) have become a widely used alternative to kD-trees as the acceleration structure of choice in modern ray tracing systems. However, BVHs adapt poorly to non-uniformly tessellated scenes, which leads to increased ray shoot-ing costs. This paper presents a novel and practical BVH con-struction algorithm, which addresses the issue by utilizing spatial splitting similar to kD-trees. In contrast to previous preprocessing approaches, our method uses the surface area heuristic to control primitive splitting during tree construction. We show that our algo-rithm produces significantly more efficient hierarchies than other techniques. In addition, user parameters that directly influence splitting are eliminated, making the algorithm easily controllable.