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MIGS06: Ken Perlin on "the illusion of life"


Ken Perlin, director of NYU's Media Lab, spoke at the Montreal International Game Summit on Wednesday on the topic of "revisiting the illusion of life." Who's Ken Perlin, you ask? Well, for starters, he's awesome.

Perlin won an Academy Award in 1997 for his work in procedural textures. He's had a hand in a large number of CG movies (including TRON), and is getting more and more involved in the video game industry.

"The illusion of life" is a term that Walt Disney first used 60 years ago, and Perlin evokes it to ask the same question. Just as Disney hoped to do in animation, can games achieve "the illusion of life?"

Perlin has been focused recently on emotion in real-time interaction. He believes that the videogame industry is in a unique position; unlike the film industry, it has the potential to direct its digital "actors" in real-time. The industry, however, can no longer rely on animators to generate emotion in characters, and it's becoming more and more important for the code to carry the brunt of the work. His first example of this is a real-time render of a face, based on his observations of a then-girlfriend. "My actual girlfriend had a higher polygon count," he admits.

Perlin uses different interface switchers to move around parts of her face, and then shows that by conjoining movements, a programmer can create emotional "chords." He illustrates this by tightening her lips, half-closing her eyes, and cocking her head back in one direction. The effect is convincing: she looks displeased. Perlin's work on emotional chords has played a large part in the emotive facial responses of characters in Valve's Half-Life 2. In fact, his real-time model is almost a dead-ringer for Alyx.

Perlin goes on to discuss the increasing importance of emotion in games. He cites the example of Facade, which he says "takes the level of psychological violence much further than shooter games... I kept saying to myself 'I'm so glad this isn't a real dinner party.'"

Perlin then shows the audience the simplest character that can be made to portray emotion. Her name is Polly, and she's only five polygons. Polly displays emotion with limited movement, like scampering, swaggering, prowling, lumbering, feeling dejected, hotfeet, sprinting, and hopping. According to Perlin, we should refer more to people's own "database of emotional knowledge," playing into expectations and letting the brain do the rest. The anithesis of this is Final Fantasy: The Spirits Within. "Don't get me started on Polar Express," he says, shuddering. He asks us to contrast this hyper-realism with a Bugs Bunny cartoon. Bugs Bunny, as a character, is believable, but "that's not the same as realism. If Bugs Bunny walked through that door, people would freak out."

He shows some more demos, the next one of two emotive virtual actors, with full-body awareness of actions. When Perlin grabs the actor's hand, the actor's entire body reacts: the feet move, the hips swivel, etcetera. Perlin considers this "full-body awareness" important to in-game animation: "the reason that all game characters are unbelievable... is because of what happens from the waist down."

His response to this is several experiments in footsteps. One applet is designed to make "smart feet." Perlin says that "we are, in our minds, magical floating heads and hands." We don't often think about the rest of our bodies, he explains, so it's hard for us to animate convincing people. In each example he shows, he focuses on creating convincing foot movements.

After a few more examples, Perlins begins to wrap up his keynote. In closing, he explains that "people care about the emotions of people... We can do things they can't do in the film world; we can go beyond film, but our techniques are much younger."

"The Graduate is a mindfuck," he says, then stops and asks "am I allowed to say that?" The audience laughs, encouragingly. "Well, anyway," he goes on, "we want [games] to be that, interactively."

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