Abstract:
This paper presents a real-time global illumination method
for static scenes illuminated by arbitrary, dynamic light sources. The
method consists of a preprocessing phase and a real-time rendering phase.
The real-time rendering algorithm obtains the indirect illumination caused
by the multiple scattering of the light from partial light paths that are
precomputed and stored in the preprocessing phase. The starting points
of partial light paths are called entry points and are sampled randomly
on the surfaces. The end points of partial light paths, called exit points,
correspond to texel centers of a texture atlas. During preprocessing the
radiance of exit points are determined assuming that the entry point has
unit irradiance, and the results are stored in texture maps, called Pre-
computed Radiance Maps. Precomputed Radiance Maps represent the
self-illumination capabilities of the whole scene. Introducing light sources
and the camera in the real-time animation phase, the direct illumination
of the real light sources can be computed by evaluating local illumina-
tion at the entry points. Modulating the Precomputed Radiance Maps
by the obtained entry point irradiance values, the indirect illumination
due to multiple re°ections can be calculated at the exit points. Adding
the direct illumination, the global illumination solution can be obtained
instantly even when the camera or the light sources move. The role of the
proposed method in games and interactive applications is similar to that
of light maps. It also renders indirect lighting of static geometry, but
unlike light maps, it allows for dynamic lighting and updates indirect
shadows and color bleeding e®ects when light sources move..