Grid-induced bounding volume hierarchy for ray tracing dynamic scenes

This paper proposes a novel method for accelerating ray tracing of animated scenes in which objects are moved, added, or deleted. The method uses two trees with different structures. The first tree is a hierarchical grid tree that is easily generatable from the primitive list and modifiable according to its change. The second tree is a bounding volume hierarchy (BVH) tree, constructed from the first tree with intra-node agglomerative clustering. When the scene is modified, the first tree is updated, and then, the second tree is partially rebuilt for accessed nodes in the first tree. The resulting BVH tree is deterioration-free; it always coincides with the tree generated by frame-wise rebuilding. For applications where a small portion of the scene is modified between frames, the tree formation cost of the proposed method is much lower than frame-wise rebuilding. Experiments showed that the quality of BVH trees generated by this method is comparable to those created by the binned surface area heuristic approach, and that the tree formation speed is faster not only for dynamic scenes but also for static scenes.