A field of grass sways in the wind, each blade clearly defined in yellow and green. A molecule of DNA, its 65,000 atoms represented by gleaming spheres, twists and folds into a thick, knotty ring. Oversize baseballs zoom by at impossible speeds, trailed by surrealistic soda fountains and eerily chattering teeth.
These remarkable images, as sharp as photographs, yet as free from the bounds of reality as an animated cartoon, were crafted not by humans but by computers. They were among the 35 video and film clips showcased last week at the twelfth annual gathering of the Association for Computing Machinery's Special Interest Group on Computer Graphics (SIGGRAPH), the equivalent of the Academy Awards for 25,000 artists, programmers and electronics engineers involved in the complex business of making computer art.
For two nights, the wide screens at San Francisco's Moscone Center glowed with some of the most sophisticated computer animations yet produced: TV commercials that showed Chevy vans floating in clouds and Norelco shavers zipping around a racetrack; television network logos replete with spinning globes and sparkling call letters; scientific simulations displaying molecules at magnifications no microscope could achieve; and animal, vegetable and mineral objects more realistically portrayed than ever before. Says Computer Artist William Reeves of Lucasfilm, who created the image of windblown grass he calls Blowin' in the Wind: "I'm not going to claim it's just like nature, but I'm pushing in that direction."
Indeed, creating objects that have natural-looking textures is one of the key challenges facing computer artists. "It's very easy to make something look smooth, like plastic or ice," says Wayne Carlson, director of production at Cranston/Csuri Productions in Columbus. "What's difficult is to give something the mottled look of bark, leaves or grass." Texture mapping, a computer technique akin to wrapping a photograph of a rough rock around a smooth stone, is one solution to the problem. Another involves the use of a class of equations called fractals. "It's a technology for filling in random surfaces in a way that mimics the way nature is random," explains Lucasfilm Researcher Robert Cook. "You want a rock to look like a rock, a random rock."
Although the results may resemble photographs or surrealistic paintings, the methods used require more mathematics than artistry. A computer artist must consider every aspect of what he wants his finished work to be and translate it into a numerical representation that the machine can comprehend.
The basic techniques by which this translation is accomplished were laid out in the late '60s and early '70s by two University of Utah professors, Ivan Sutherland and David Evans, in fulfillment of a contract for the U.S. Department of Defense. Their task: to build a flight simulator for pilot training that would show on a screen the same unfolding landscape the pilot would see from the air. To do this, the Utah scientists first had to program into the computer a precise mathematical model of every tree, house and mountain in the flight path. Then they instructed the machine to put each of those objects into three-dimensional perspective, to give it the illusion of depth and to eliminate those surfaces that would be hidden from the viewer's line of sight.