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MIGS: Ken Perlin on the Illusion of Life

Ken Perlin, a professor from the Department of Computer Science at New York University, discussed "The Illusion of Life, Revisited" in his MIGS keynote, talking about ways to imitate life in games by 'not simply using traditional animation techniques'.

November 8, 2006

5 Min Read

Author: by Mathew Kumar, Montreal

Ken Perlin, a professor from the Department of Computer Science at New York University, opened his Montreal International Game Summit talk, “The Illusion of Life, Revisited” by referencing Walt Disney’s comments that animation creates “the Illusion of Life”, a statement made over 60 years ago. With video games not even born by the time of Disney’s statement, Perlin argued that the industry had a lot still to learn about the possibilities on offer to create the illusion of life in games; most strikingly by not simply using traditional animation techniques. The Reality of the Illusion of Reality Today After introducing slides of what Perlin argues is most currently possible of being directed in real time (a blocky, Unreal Tournament-esque warrior) versus what he imagines game creators would like to direct in real time (if not John Wayne, at least Shrek), he moved straight into discussing and exploring his research. The majority of this used Java applets, freely available for use from Perlin’s website. His first demonstration, of a 3D face with different section of the face modifiable in a limited fashion (i.e. eyebrows either up or down) allowed Perlin to describe the ease in which by combining movements of part of the face, expressions are instantly recognizable. “It was actually based on my girlfriend of the time, I’d see her expressions and add them to the software” Perlin mentioned, and taking the audience through the angrier facial expressions he added, “I was seeing these expressions towards the end of this phase of my research…” As simple as the software seemed, Perlin revealed that it's used by a group in Texas to help children with autism learn facial expressions, and Valve used it to inform the creation of the faces in Half-Life 2. Proper Movement is worth More than Photorealism “When you see a movie … the only reason you care about what happens (because remember, unlike a game you can’t even change anything) is because you care about the characters.” Perlin declared, before explaining how the emotional aspects of Michael Mateas and Andrew Stern’s Façade (which “takes the level of psychological violence much, much further than a shooter game”) led Perlin to ask, “What’s the simplest character I can make that you can get a sense of emotional interaction from the character.” Creating a character out of the minimum number of polygons (a 3D triangle) and calling it Polly, he gave it a variety of expressive animations; walking sadly and slowly, running and skipping or bouncing up and down. “The interesting thing that is that most of what happens there [seeing emotion] happened inside of your own brains, visually processing the images and mapping them into cultural and physical stuff. This is something inside everyone’s brain we can work with, if we know how to tap into it.” Perlin continued, “We don’t need to go for more and more photorealism in the absence of proper movement. Think about Final Fantasy the movie versus any Bugs Bunny cartoon; don’t even get me started on Polar Express! But Bugs Bunny is believable; you know him and understand him. But that’s not the same as realism; I conjecture that if Bugs Bunny walked through the door right now people would freak out.” The Power of Layered Procedural Animation Perlin proceeded to run through his research which expanded more deeply on the power of animation, specifically procedural animation. He showed a demonstration of his Emotive Virtual Actors, procedurally animated characters that allow the user to be a “virtual acting coach” and modify the actor’s form (i.e. shorten their legs and bend their backs) to alter the actor’s “acting”, modifying the actor’s walk even though it is still based on an original animation. Perlin argued for a system with “layers of creation” for animation in video games, with the lowest layer animation of physical movement (in a walk: where do all the joints go?) the next the physical direction (directing the shoulders to be hunched and the knees to be bent), higher still the emotional direction (an angry walk) and finally, the actor’s response to events or other actors (in response to another actor’s angry walk, that actor will perform their own angry walk). Discussing walking, in fact, Perlin opined, “The reason that all game characters are unbelievable, and they’ll always be unbelievable no matter what you do, is because of what they do from the waist down.” As the feet and legs require weight to shift to animate realistically (compared to the upper body) animating the legs is a far harder proposition, Perlin commented, showed his “Smart feet” engine, his example of procedurally animated legs. Time has Run Out for Timelines Perlin rewarded the audience of the Montreal Game Summit with a sneak peak of his research in progress, software that aims to make animation as simple as using a whiteboard: simply sketching lines to direct actors or draw walls, with actions on a time line. Perlin exclaimed, “It shouldn’t be a timeline, it should be more like a script. We really want to get rid of timelines and replace them with scripts, as they’re conditional, and supply their own AI. We want smart, ‘director’ software.” With his final thoughts, Perlin challenged the audience to work towards creating a video game equivalent of Casablanca; “That’s where the good stuff is; it doesn’t matter what happens in Casablanca if you don’t care about the character that Humphrey Bogart creates. We want to get that intensity, that vividness of character into interactive experiences, where I believe it’ll be even more powerful.”

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