If we’re trying to achieve realistic lighting in a computer graphics scene, why not just use an environment map for the lighting? This approach to illumination is called image-based lighting; it has been popularized in recent years by researcher Paul Debevec at the University of Southern California. Churches and auditoriums may have dozens of light sources on the ceiling. Rooms with many windows also have complex lighting environments. It is often easier and much more efficient to sample the lighting in such environments and store the results in one or more environment maps than it is to simulate numerous individual light sources.
The steps involved in image-based lighting are as follows:
1. Use a light probe (e.g., a reflective ...