Re:PowerVR Wizard GPU does real-time ray tracing at 10x lowe...
by alkonaut on Thursday January 07, 2016 @05:09PM
(#10861201)
PathTracing (Though not regular Ray tracing) is actually pretty tricky to parallelize. I'd be interested in hearing what their hardware actually does? I'm guessing some hardware implementation of ray intersections with a BVH or kd-Tree?
The problem that occurs when trying to do path tracing on current hardware is that secondary (reflected) rays are incoherent so the gpu will stall one ray while waiting for another that hit something, leading to poor utilization of the gpu. It's still normally faster than on a cpu, but compared to "simpler" problems like some linear algebra (Machine Learning or similar) the perf of gpu vs cpu is low.
Re:PowerVR Wizard GPU does real-time ray tracing at 10x lowe...
by cma on Thursday January 07, 2016 @09:44PM
(#10862586)
I thought GPU techniques do something like accumulate the secondary rays and use really fast GPU sorting algorithms on them before continuing, to bring back coherence.
The problem that occurs when trying to do path tracing on current hardware is that secondary (reflected) rays are incoherent so the gpu will stall one ray while waiting for another that hit something, leading to poor utilization of the gpu. It's still normally faster than on a cpu, but compared to "simpler" problems like some linear algebra (Machine Learning or similar) the perf of gpu vs cpu is low.