For several decades now, computer graphics simulations have been used for a wide range of tasks such as pilot training, automotive design, and architectural walkthroughs. The entertainment industry has developed techniques for creating startling special effects and realistic simulations. Even virtual reality games use convincing imagery with great success. But are these images correct? Would they accurately represent the scene if the environment actually existed? In general, the answer is no, although the effects are appealing because the images are believable.

For the past decade or more we have been developing a system to test, validate, and improve the fidelity and efficiency of computer graphics algorithms. Our goal is to develop physically based lighting models and perceptually based rendering procedures for computer graphics that will produce synthetic images that are visually and measurably indistinguishable from real-world images.

Over the past two years the we have articulated and refined a framework for realistic image synthesis, presented in a special SIGGRAPH session in August of 1997. This framework articulates future research goals for physically-based global illumination through a major multidisciplinary effort among physicists, computer scientists, and perception psychologists.

Our research framework is subdivided into three sub-sections:

• the local light reflection model
• the light transport simulation
• the visual display algorithms

In addition to improved computer graphics rendering, this major paradigm shift from "looking good" to "measurably good" will make it possible to use computer graphics in a predictive manner. With this key element of fidelity, our algorithms can also be used for testing and developing printing technologies, photographic image capture, the design of display devices, and algorithmic development in image processing, robotics and machine vision.