Tom Porter’s Pixar colleagues agree: without Porter’s innovation, Buzz Lightyear might never have flown, Nemo would have washed out, and the Incredibles would have been, well, ordinary.
A three-time Academy Award winner in scientific and technical categories, Porter, an associate producer, is credited with the breakthrough that made computer-animated films a viable art form.
Back in the early 1980s, Porter, MS ’75, was one of a group of computer programmers at Lucasfilm, the production studio of Star Wars creator George Lucas. Tron, a 1982 film that merged real actors with computer-generated images, had garnered tepid reviews and disappointing audience response. As financial support for future projects dried up, computer animation faced an uncertain future. “We knew we were doing important work,” Porter says. “We just didn’t know if anyone else felt that way.”
A central stumper was how to reproduce a phenomenon known as “motion blur” that gives movie action a natural look and feel. Every time a frame is shot in live-action filming, a nearly imperceptible blur is recorded as objects move during the split second it takes for the camera’s shutter to close and reopen. String these frames together and a faint smear gives one image a seamless transition into the next. This blur can be easily simulated by hand in traditional animation.
A quarter century ago, however, no one had figured out how to create this effect using computer images, which were rendered perfect and whole. There was no natural blurring to wash them together. As a result, objects seemed to pulse across the screen, like a strobe light, causing the viewer’s eye to rebel.
Two of Porter’s Lucasfilm colleagues laid the groundwork for his later work by determining how to distinguish foreground from background colors in static images. Rodney Stock came up with the idea of “dithering”—sampling points on pixels at the edge of an animated object to determine a transition color that would properly blend foreground into background. Another colleague, Rob Cook, spent a year figuring out how to do it. Cook developed a method that looked at 16 randomly selected points inside each pixel—one of about a million of the tiny rectangles of color that compose a digital movie image—to assign that transition color. But while Cook’s work guaranteed smooth transitions between foreground and background in still images, it didn’t free animated images to move.
A central stumper was how to reproduce a phenomenon known as motion blur that gives movie action a natural look and feel.
Porter’s breakthrough came in what he describes as “one of those lovely moments,” probably while driving home or working around the house: “I thought, ‘We can solve this if we think about it in a different way.’”
Cook’s 16 pixel points represented the same instant in time. Porter proposed looking at those 16 points during the 1/60th of a second that a theoretical film camera shutter opens and closes. During that interval, various objects—a dog, a flurry of leaves—would pass over that fixed pixel. Porter’s solution: identify the color of each of those randomly selected 16 points at those moments, which enabled him to assign an average or “negotiated” color to each pixel and simulate the blurring effect needed to make a movie.
Porter downplays the originality of the idea: “This is the most trivial insight. It isn’t rocket science.”
Ed Catmull disagrees. Catmull, now president of animation for Disney and Pixar, was head of the computer division at Lucasfilm at the time. He calls Porter’s innovation “a bizarre concept that turned out to be true. [Without it] it wasn’t clear that the solution to motion blur would have been discovered.”
In nearly 30 years in the field—he also is renowned for his work on digital compositing and high-resolution painting—Porter has seen computer animation go from nowhere to the stratosphere. When he was a graduate student at Stanford in the early 1970s, the computer science department was an “academic backwater,” he says. The subcategory of computer graphics consisted of simple line drawings. Then one day Porter saw 2001: A Space Odyssey and heard the film’s special effects director, Douglas Trumbull, describe how his team created the realistic space scenes. “The whole thing looked seductive to me; the prospect of making these gorgeous images,” Porter recalls.
After Stanford, Porter went to Washington, D.C., to become the computer graphics programmer in the molecular modeling laboratory of the National Institutes of Health. But government work was a far cry from 2001. He interviewed at special-effects shops in Los Angeles, but found the pace too hectic. He moved to the Bay Area to work at Ampex, a broadcast engineering firm, and in 1980 he sat across from CBS newsmen Walter Cronkite and Dan Rather while they analyzed vote counts state by state. The graphics machine Porter helped develop turned some states “red” and others “blue,” depending on which candidate had won.
The next year, between the releases of the second and third Star Wars films, George Lucas hired Porter to come to Lucasfilm. He followed Catmull, whom Lucas had hired away from the New York Institute of Technology.
Porter has been at Pixar since its founding in 1986. He supervised shading and visual effects on Toy Story, headed up the technical direction of Monsters, Inc. and served as associate producer for Cars.
Porter and his wife, Armav Christine Baron, live in Marin County. They have three sons, Chase, a sixth-grader, Ross, a Stanford senior majoring in mechanical engineering, and Spencer, ’05.
Though he rejected the Hollywood scene early in his career, Porter admits he enjoys the hoopla of the Academy Awards. “The year Ashley Judd hosted the awards, somehow my bow tie was askew. Here this gorgeous woman takes pity on this nerdy scientist and comes up and fixes it,” he recalls. He took his mother-in-law to the first awards ceremony he attended. His wife went along for the second. Now he’s working his way through his four sisters.
Will computer-animated films one day be so realistic they might supplant real actors? No way, says Porter. “You have to realize that ‘realistic looking’ isn’t enough,” he says. “What Jack Nicholson offers is the ability to send shudders down your spine. You’ve got to put interesting characters on the screen. I’m not the least bit concerned about pursuing reality as the Holy Grail.”
Ann Marsh, ’88, is a writer in Long Beach, Calif.
