Fused Collapsing for Wide BVH Construction

We propose a novel approach for constructing wide bounding volume hierarchies on the GPU by integrating a simple bottom-up collapsing procedure within an existing binary bottom-up BVH builder. Our approach directly constructs a wide BVH without traversing a temporary binary BVH as done by previous approaches and achieves 1.4−1.6× lower build times. We demonstrate the ability of our algorithm to output compressed wide BVHs using existing compressed representations. We analyze the impact of our method on software raytracing performance and show that it reduces the overall frame time on complex dynamic scenes where rebuilding the BVH every frame is the limiting factor on rendering performance.