They're generating millions of rays to trace them at the same time, so they shou...

They're generating millions of rays to trace them at the same time, so they should be able to use packet tracing and they seem to use that [1]. Incoherent rays can be extremely troublesome when tracing packets, as you could be entering a branch of the BVH for just a few rays in the packets and in that case you're wasting a large part of the SIMD vector. There has been some research to alleviate that [2, 3] and creating more cohorent batches alleviates it even more. One of the other big problems of packet tracing is that there is no good way to handle motion blur, but if they're generating millions of rays at once they can just create packets with rays that are all in the same time interval.