Performance Considerations

Ray-tracing is very compute intensive. PBRT-v3 runs on the CPU, but is excellent at using multiple CPU cores. So it runs best on a multi-core CPU.

Even with a fast CPU, rendering can take a long time. To reduce the amount of time required, consider reducing the resolution of your image to what you really need. Similarly, reducing the number of rays per pixel will also make your code run faster.

Near Future: Moving to the GPU

PBRT-v3 runs entirely on the CPU. Moving a physically-accurate ray tracer to the GPU is quite challenging, but PBRT-v4 has managed to do it (at least for recent model Nvidia GPUs). We are actively working to move ISET3d to support PBRT-v4, but it is still a work in progress.