Fast BVH construction and refit for ray tracing of dynamic scenes

As the complexity of virtual environments increases, it becomes a critical issue to ray tracing of dynamic scenes interactively. In this paper, we propose an effective method to address this issue. Firstly, we improve the Surface Area Heuristics (SAH) based bounding volume hierarchies (BVHs) construction algorithm and present a sub-interval search criterion for predicting the optimal split plane position. Compared with the standard SAH approach, our algorithm is much faster but has a little quality degradation. Secondly, we present two new BVH refitting operations, which could run fast and obtain considerable quality of BVHs. The two operations are general and applicable to complex and dynamic scenes including a wide range of deformation. Lastly we use multithread to handle the dynamic scenes during animation, one thread for BVHs rebuilding asynchronously, the others for BVHs refitting and ray tracing. The results of this experiment show that our method is effective. Compared with the previous works, it obtains higher and smoother frame rate.