Computer Science Department
School of Computer Science, Carnegie Mellon University
Simulating Soft Shadows with Graphics Hardware
Paul S. Heckbert, Michael Herf
An abbreviated version appeared in "Fast Soft Shadows",
For a diffuse scene, the method precomputes a radiance texture that captures the shadows and other brightness variations on each polygon. The texture for each polygon is computed by creating registered projections of the scene onto the polygon from multiple sample points on each light source, and averaging the resulting hard shadow images to compute a soft shadow image. After this precomputation, soft shadows in a static scene can be displayed in real-time with simple texture mapping of the radiance textures. All pixel operations employed by the algorithm are supported in hardware by existing graphics workstations. The technique can be generalized for the simulation of shadows on specular surfaces.