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from ink to pixels
Keyframing
Motion capture
Simulation
from pixels to...
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Getting animated over computer animation
17 Dec 1998. Seen Toy story? Seen Antz? Then you know computer animation has entered the big time. Most recently, A Bug's Life mauled the multiplexes, selling $46 million in tix on the critical Thanksgiving weekend. Not bad for a film about a group of befuddled ants who get the super hero treatment from -- a bewildered flea circus?

bug's life
Click here to download 8MB QuickTime movie. Photos by Lorey Sebastian. ©Disney Enterprises, Inc./Pixar Animation Studios. All rights reserved.


hopper

Photos by Lorey Sebastian. ©Disney Enterprises, Inc./Pixar Animation Studios. All rights reserved.

Who wouldn't love those ants -- diligent and cooperative, obediently following their queen as they calmly gather their fall grain harvest. Then, like a squad of Roman centurions, the evil grasshoppers buzzed onto the scene -- as delightful as Darth Vader, as tender as the Terminator, as welcome as a besotted band of Hell's Angels at a cotillion, demanding extortion in the form of grain for the winter.

It's obviously a fancy remake of Aesop's fable, "The Ant and the Grasshopper." But this being a Disney flick, we know that Flik, the feckless good guy, will triumph in the end -- through a combination of luck, pluck, and sheer steadfastness.

Meanwhile, behind the scenes
But what really grabbed our attention was animation that avoided the human hand on the pencil or paintbrush. Like Toy Story, the pathbreaking 1995 Pixar production, Bug's Life emerged from a bank of computers, cut, as it were, from whole silicon.

Jessica Hodgins, who experiments with computer animation at Georgia Institute of Technology, was particularly impressed with the opening and closing scenes, with their waving grasses and hordes of ants working together. "To make each character look slightly different, so they are doing the same thing without moving in lockstep" is still problematic for crowd scenes, she points out.

heimlichWhat is computer animation? How is it done? And what's next for this merger of high technology with cartooning? These are the questions that are bugging the Why Files. So let's wave all four arms -- like the insects in the movie -- and poke our bug eyes into the odd world of computer animation.

Three major techniques
The boffo box office of A Bug's Life leaves us no choice: It's time to figure out how this stuff is made. Computer animation builds on the techniques pioneered by Walt Disney. Walt bought his prosperous Land and World with Donald Duckian sagas that fooled the eye with a rapid series of ever-changing, hand-drawn still pictures.

ant island

The newer technique substitutes powerful digital graphics for the artist's hand. Instead of drawing pictures, animators use software to create various kinds of models, then endlessly manipulates them with software. Eventually, a scene is rendered, or drawn, taking hours or even days on the kind of jump-start computer most people only dream about. (For a discussion of animation old and new, see "Principles of Traditional Animation ..." in the bibliography)

Despite the success of Toy Story and A Bug's Life, computer animation is about much more than making modern Mickey Mouse movies. It also assists in scientific pursuits and dramatic movies. In Titanic, for example, digital effects were seamlessly joined to footage of the physical model of the Titanic and were used to portray a sequence toward the end, in which the miniature submarine floated down a flooded corridor in the sunken liner -- and then, time warp fashion, entered a fully populated grand ballroom, dry and filled with the doomed guests.

As Hodgins points out, computer animation is diverging into two genres. One form is merging with conventional pictures, and another is creating cinematic works using nothing but ones and zeroes (not really, but you get the picture).

In either case, the animation relies on three basic approaches:

  1. Keyframing. The technique that's most similar to conventional animation, keyframing requires animators to draw key frames on a computer. These logically named objects show, say, every half-second of the action. The computer then creates the in-between frames more or less automatically. Keyframing requires a lot of animator talent -- since they must draw the initial pictures. If you want to see top-flight keyframing, check out A Bug's Life. End of plug.

  2. Motion capture. Models wear special badges that allow a group of video cameras to track their motion. A relatively low-rent technique that produces realistic motion, capture relies on models to jump-start the process.

  3. Simulation. Computer models simulate the motion of a person or animal, based on the laws of physics. The computer establishes a software program that makes, say, an arm, with two segments, connected by a hinge at the elbow. If you know the mass of each segment and the position of the shoulder joint, you should be able to predict how the arm can move when the bicep contracts.

Let's get the details on each technique. Keyframing comes first: How did Pixar get antsy?


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