Canned Lightsources

Complex luminaries and lamp geometries can greatly increase the realism of synthetic images. Unfortunately, the correct rendering of illumination from complex lamps requires costly global illumination algorithms to simulate the indirect illumination reflected or refracted by parts of the lamp. Currently, this simulation has to be repeated for every scene in which a lamp is to be used, and even for multiple instances of a lamp within a single scene. In this paper, we separate the global illumination simulation of the interior lamp geometry from the actual scene rendering. The lightfield produced by a given lamp is computed using any of the known global illumination algorithms. Afterwards, a discretized version of this lightfield is stored away for later use as a lightsource. We describe how this data can be efficiently utilized to illuminate a given scene using a number of different rendering algorithms, such as ray-tracing and hardware-based rendering.