Radiosity Engine

RADIOSITY ENGINE COMMENTS A further discussion of features and techniques for the Electric Image Universe Radiosity Engine. VERSION 1.0 • © COPYRIGHT 2003 CONTENTS GENERAL DISCUSSION 2 Form-Factors Hierarchy Progressive Refinement The Different Methods SOLUTION SETTINGS 5 Minimum Energy Level Source and Receiver Density Resolution and Refinement Levels Visibility Tolerance Energy Reflection LIGHTS 7 Light Size Reflectors Size and Distance Distant Light Sources GEOMETRY 11 Double-Sided Geometry SUBDIVISION 12 Special Cases LIGHT SIZE EXPERIMENTS 15 LIGHT SHAPE EXPERIMENTS 17 RADIOSITY ENGINE COMMENTS GENERAL DISCUSSION Basically, a radiosity engine calculates how much energy reaches each surface in a scene—both from light sources and from all other surfaces in the scene. Radiosity is the rate that energy leaves a light source by emittance, or other surfaces by reflectance. An application that calculates radiosity values throughout a scene is called a radiosity engine, the process is called a simulation, and the result is referred to as a solution. The radiosity can be represented in the visual spectrum—a color, and as such, is useful for computer graphics. The engine determines the visibility between two surfaces, or how much of a source surface is visible to a receiver surface. The visibility is multiplied by the emittance or reflectance of the source surface to determine the form-factor, or the amount of energy transferred between the two surfaces. The engine repeats this process many times for every possible pairing of surfaces in the scene. Most rendering methods, including Phong and ray-tracing, treat light sources as distinctly different entities from the surfaces they illuminate. Radiosity methods, however, treat all surfaces equally—a light source is simply a surface emitting e…