STBVH: a spatial-temporal BVH for efficient multi-segment motion blur

We present the STBVH, a new approach for rendering multi-segment motion blur using a bounding volume hierarchy (BVH) that stores both spatial linearly interpolated bounds and temporal bounds. The approach is designed for different number of time steps per mesh or object. While separating the individual meshes using standard partitioning techniques, it performs temporal splits for locations with large or curved motion inside the meshes. Our approach uses a modified motion blur surface area heuristic (MBSAH) that calculates probabilities in the presence of spatial-temporal bounds and works on linear motion segments of primitives rather than on full motion curves. We show that our approach is able to handle challenging scenes with varying degrees of motion blur per mesh, using significantly less memory and having competitive rendering performance compared to building separate linear motion blur BVHs per global time segment.