Title: Specifying and encoding appearance descriptions
Abstract: This chapter reviews the various approaches to specification and discusses how material properties can be represented in the computer for efficient processing and rendering. The most common approaches to the specification of complex appearance characteristics relies on interactive tools and visual inspection by users, while others use the power of composition and programmability to define shaders and assemble complex appearance behavior from simple building blocks. The question of selecting the adequate parameters of a given appearance model, in order to achieve a desired look, remains a major difficulty for CG artists and designers. The simplest mechanism for specifying a set of appearance parameters for digital processing is, at least from a computer's point of view, by means of a computer file. At the opposite end of the spectrum from interactive, direct-manipulation approaches, manually editing a catalog of parameter values is an effective, if tedious, way to control appearance. The Radiance lighting simulation system, which became a reference tool in professional lighting engineering in the 1990s, used this technique for handling material and light descriptions. Radiance material files use a fixed syntax modeled after the BRDF and lighting models used internally by the simulation program, and all parameter values are explicitly indicated. However, this system is not entirely monolithic since it also uses a simple form of programmability: Procedures (external programs) can be invoked to generate data such as patterns. The radiance system, therefore, offers a computer-oriented view of appearance specification, with a set of possible operations (programs) invoked using manually specified parameters.
Publication Year: 2008
Publication Date: 2008-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
Access and Citation
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot