The photon pipeline

We propose a pipelined architecture to accelerate high quality global illumination. Ray tracing can be done in real-time, so the main challenge is how to combine the visibility information from ray tracing with the global illumination information from photon tracing. Our architecture is based on reverse photon mapping, which, under reasonable assumptions, is algorithmically faster than photon mapping without sacrificing versatility or visual quality. Furthermore, reverse photon mapping exposes fine-grain data objects, photons, which can be efficiently pipelined through our architecture for very high throughput. Because photon mapping is bandwidth-limited, we use cache behavior and bandwidths to measure the effectiveness of our approach. Simulations indicate that this architecture will eventually be able to render high-quality global illumination in real-time. We believe that fine-grain pipelining is a powerful tool that will be necessary to achieve real-time photorealistic rendering.