THE DIGITAL ARTS

Movement without Motion,
Dimension without Volume:
New Wrinkles in Computer Animation at NYU

by David Frederickson

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Hollywood and Industrial Light and Magic awed viewers with the 3D animations in "Jurassic Park" a while ago: lavish effects that, we were told, cost millions of dollars to produce. They also cost weeks of heavy-duty computer time, since each frame had to be rendered separately, and each contained dozens of elements with their own characteristics of volume, motion, color, surface, lighting, and so forth, each of which had to be calculated -- and that's after the objects were painstakingly constructed in the first place.

All very well, but there has to be an easier way.

Here in the Animation Area of the Department of Film and TV at NYU's Tisch School of the Arts, Peter Bardazzi has been taking students through the paces of computer animation for nearly a decade. Over the years, the computer tools they've been using have been growing more and more powerful: hardware such as the SGI Indigo 2 computers and the Abekas frame buffer at the ACF, and software such as the animation program Alias. And Bardazzi and his students have been learning to make the most of them.

Normally, a character in a computer animation is built up out of various geometrical objects -- spheres, cubes, cylinders -- which are distorted and modified and added together and colored and animated with various computer tools until the creator is satisfied (or runs out of time). One of the tools, surface mapping, lets the artist apply a picture of a surface or texture (marble or woodgrain, say) to an object.

But the surface map itself can become the object, it seems. Working with Brian Caulfield, a PhD candidate in the Department of Computer Science (GSAS), Bardazzi has managed to create some strong 3D effects on a relative shoestring.

Starting with a couple of picture postcards, they took images of a statue of Buddha and a temple wall, gave them dimension, and animated a sequence that has the viewer moving through the space, looking at the statue. Part of the effect is the result of having the statue and the background move relative to each other -- an effect that's long been familiar in animation, where foreground objects drawn on a transparent cel (short for cellophane, by the way, the precursor of today's transparent plastics) are moved in front of an opaque background. But in Alias, the postcard Buddha can be turned into a (simulated) 3D object by using lightness and darkness to define dimension, pushing brighter objects forward and darker back. Thereafter, Alias treats the Buddha as it does any other 3D object, allowing the "viewer" to move around it (but not too far, since the statue will ultimately be revealed as a bas- relief with a hollow back). Dimension without volume.

Surface mapping can provide the effect of animated titles, too, Caulfield and Bardazzi found. Setting type on a computer is old- hat by now; it's been done commercially for thirty years or so. And it can be done in Alias as well, with letters turned into 3D objects that can fly around the screen, or chug after each other in a train, or whatever. Unfortunately, that takes a lot of computer time.

But if you let the type stand still and reflect it off a surface that appears to be moving, you've got apparent motion. Picture a funhouse mirror reflecting the type; now picture the various dips and bulges of the mirror in motion, sending the type swirling around. Here, however, the reflective surface is defined as the inside of a hemisphere, which re-reverses the type that would have been reversed by reflection. Caulfield insists that it's only the surface map on the hemisphere that appears to be moving -- he apparently thinks the hemisphere itself is real and stable, and only the map is an illusion.

Welcome to Hyperreality 203.