If you haven't seen path-tracing before, you should check out LuxRender: http://www.luxrender.net/ It's an open source unbiased renderer that uses similar techniques.
It's a massively parallel problem, so the recent abilities to run general purpose code on a graphics accelerator has really been a huge boost to performance something like: http://www.youtube.com/watch?v=70uNjjplYzA would have been impossible before CUDA came out.
It's a massively parallel problem, so the recent abilities to run general purpose code on a graphics accelerator has really been a huge boost to performance something like: http://www.youtube.com/watch?v=70uNjjplYzA would have been impossible before CUDA came out.