Animated characters are likely to move out of the lights providing the specular highlights with the setup just described. It is sometimes beneficial to parent (attach to maintain a fixed relative position and orientation) the eye lights to the character so that they move wherever he does. For this to appear believable, it is important to have the lights inherit the translations but not the rotations of the character. If they follow both the translations and rotations, the specular highlights will appear on the exact same spot in each eye, no matter how much the character moves and rotates, in every frame of the shot.

The best reference for creating believable CG eyes is found in studying the eyes of everyone around you. Look closely and see what gives a person’s eyes depth and life. Also, look at the films with CG characters you think are particularly lifelike, and study their eyes. Chances are the lighting artists who created them paid a great deal of attention to the eyes.

The Dangers of Accuracy
Several of the headings in this chapter point out ways to add detail and realism to CG renders and make them more believable. Before attempting to include all these techniques in creating the perfect computer graphics scene, step back and evaluate the visuals created by all these techniques. Numbers can be perfect but still look wrong. As with a lighting diagram, the reference and data is collected and interpreted but not blindly entered into the computer as the final lighting data of a scene. The end result is the key, and the eyes are the only true judges. If the numbers all say it is a perfect match, but everyone you show it to says it looks out of place, then the numbers are wrong. Do not fall in love with numbers, symmetry and the enticement of an image in which every pixel fits neatly into a predetermined equation. The way light sculpts the forms of a scene is an organic process. The difference between a natural lighting setup and a crystal-clear, shiny computer graphics scene is obvious to the most casual observer.

With that said, attention to detail is still extremely important. The details in the eyes help the viewer identify with a character and add life to CG creatures. Reflections tie elements in directly with the elements surrounding them, and motion blur helps to mimic the recording process of a film camera. Cookies and shadows offer methods for occluding light to add both realism and compositional interest to a scene. Each of these techniques can be explored to give the lighting artist indispensable tools for creating quality computer graphics imagery.

To learn more about lighting and compositing and other topics of interest to animators, check out Inspired 3D Lighting and Compositing by David Parrish; series edited by Kyle Clark and Michael Ford: Premier Press, 2002. 266 pages with illustrations. ISBN 1-931841-49-7. ($59.99) Read more about all four titles in the Inspired series and check back to VFXWorld frequently to read new excerpts.

David Parrish (left), Kyle Clark (center) and Mike Ford (right).

David Parrish went straight to work for Industrial Light & Magic after earning his master’s degree from Texas A&M University. During the five years that followed, he worked on several major films, including Dragonheart, Return of the Jedi: Special Edition, Jurassic Park: The Lost World, Star Wars: Episode I — The Phantom Menace, Deep Blue Sea, Galaxy Quest and The Perfect Storm. After five years with ILM and a short stay with a startup company, he was hired by Sony Pictures Imageworks to work on Harry Potter and The Sorcerer’s Stone.

Series editor Kyle Clark is a lead animator at Microsoft’s Digital Anvil Studios and co-founder of Animation Foundation. He majored in film, video and computer animation at USC and has since worked on a number of feature, commercial and game projects. He has also taught at various schools, including San Francisco Academy of Art College, San Francisco State University, UCLA School of Design and Texas A&M University.

Michael Ford, series editor, is a senior technical animator at Sony Pictures Imageworks and co-founder of Animation Foundation. A graduate of UCLA’s School of Design, he has since worked on numerous feature and commercial projects at ILM, Centropolis FX and Digital Magic. He has lectured at the UCLA School of Design, USC, DeAnza College and San Francisco Academy of Art College.