Radiosity
Research by: Kimberly Chan, Julian Falkenburg, & Trent Willis
Overview
What is Radiosity?
Radiosity is a lighting algorithm that provides realistic, high detail lighting of a 3D scene. The surfaces in the scene must diffuse light, as the radiosity algorithm works by simulating the path that light takes from a light source to the viewer. This creates a vivid scene where lights and shadows are gradients, and there are numerous softer, subtle lighting effects. Colors of one surface leak onto others, and areas around light sources glow with light. The simulation works by dividing up the surfaces to be rendered in a scene, and seeing how well each surface's light can interact with surrounding surfaces. There is an iterative aspect of the algorithm, which uses multiple passes to see how the scene is illuminated after the light makes a series of bounces from surface to surface. Lightmaps (pre-computed brightness mapped to 3D objects) allow radiosity to be displayed in realtime, on computers with graphics acceleration hardware.
Radiosity's Relationship to Digital Arts & Sciences
Radiosity is used as a part of 3D graphics engines in modern videogames, as well as 3D graphics programs like Autodesk. Efficient implementation of radiosity allows its use in both real-time and pre-rendered 3D graphics. Linear systems of equations are used to determine view factors. When these matrix equations are solved, the brightness of each patch is revealed. Radiosity has a basis in thermal radiation, due to how it simulates brightness by computing how light is transferred between surfaces. Radiosity is an important part of 3D lighting, which is vital to rendering a 3D scene. Radiosity is a simple to implement, very effective global illumination algorithm. Efficient computation of radiosity is not trivial; there are multiple ways to finding the radiosity of a scene, including methods that employ iterative solutions and reduce computation time. Adaptive integration can be used to reduce the computation time from n log n.
