Abstract: Rapidly simulating global illumination, including diffuse and glossy light transport is a very difficult problem. Finite element or radiosity approaches can achieve interactive simulations for some classes of diffuse-only scenes, but more general methods are currently too slow and too noisy for interactive use.

We present a new method which seamlessly integrates particle tracing (for non-diffuse transport) into the gather step of hierarchical radiosity (for diffuse transport) to efficiently handle all types of light transport chains. Our integrated approach results in rapid, good visual quality solutions. This is achieved using a radiosity algorithm producing smooth, noise free simulation of diffuse light transfers, and an integrated particle trace for rapid, high quality specular reflections such as caustics.

Using our system, users can interactively visualize and manipulate small environments with global illumination including specular effects. Such general lighting effects can also be simulated for larger environments, albeit at a higher computational cost. Our system can also treat scenes which are lit mainly by indirect lighting, which is very hard using previous methods. With our method, smooth transition from fast, low quality to slower high quality solutions is possible.