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From the Summer 1988 issue of Animation Magazine

Cartoony Computer Animation at Rhythm & Hues

By Phil Denslow

After the collapse over the last few years of such prominent computer animation studios as Robert Abel & Associates, Digital Productions, Omnibus, Cranston Csuri and Whitney-Demos, several groups of former employees have banded together to pick up the pieces and continue doing commercials. One of these is Rhythm and Hues, founded by John Hughes (former head of production at Abel) and Charlie Gibson (a senior technical director and software designer at Abel & Digital). Among other developments, they have achieved real cartoony animation on their system by changing the way their animators control motion with the computer.

Until now, most computer animation systems allow for the grouping and movements of segments of a character, but are limited by the restrictions caused by establishing a hierarchy of those segments. The "hierarchal choreographer" program tells the computer how various objects are linked together for control of their motion. For example, the segments of a finger would be linked to the segment of the hand, which would be linked to the forearm, which would be linked to the upper arm, etc. All this would then allow the animator to move the upper arm and carry the lower segments along with it. The fingers could still have movements of their own, but these would happen in relation to the overall motion of the arm. Simple scaling changes could be made to the segments, but any complex change in the segments, such as squash and stretch along the path of action, would have to be created by "object editing" or digitizing" the extremes of the motion, which requires rebuilding the segments of the character or object. But at Rhythm & Hues this can all be done by the computer.

This allows much more creativity in moving a character or object. By giving the animator a simplified representation of the positions of the parts to be moved, the computer can almost instantly show a preview of the motion. This allows the animator to quickly modify and/or add the key frames that the computer uses to create the inbetweens. They have applied their new methods to commercials for 7-UP and Sunbeam. In the Sunbeam spot, realistic toasters and teakettles jump and run just like Tom and Jerry, utilizing all the squash and stretch any traditional animator could want.

"You're animating volumes," Gibson says, "rather than animating physical objects. You animate the space around an object and the object is in that space. You distort it or stretch it out and the object will stretch with it . We've simplified the levers that you're pulling to see your animation and refine it. The only way you can really refine the animation is to look at it a lot, modify it a lot, and be able to really get in and tweak it. If you're doing object animation and digitizing extremes, it's so much work that you're going to get sick of it, get bored, run out of time, or something, before your animation is nearly complete.

"There's a classic problem in using a hierarchical choreographer like Wavefront's, or the Abel software. Someone asks you to animate a walk cycle or something like that, and it's very difficult because the hierarchy is set, and usually you design your character with some goal in mind. You know you want to be able to tell a story, and those goals may vary from second to second in animation.

"For example, a walk cycle requires that the character's feet be on the ground. So you think: Ok, I'll build the hierarchy from the feet up. Wherever I move the feet everything else goes along. That's great, except when I rotate the ankle, the whole body rotates with it, and it's stiff all of a sudden. So you have to go and compensate for that, and you start running into problems. So then you say: Maybe the center of gravity is the best place for the origin of the body to be, so you slide him along and try animating the feet, but it really doesn't work because the toes and feet don't look like they're on the ground. Or the toes dig into the ground. But you're always limited, because with hierarchy everything is attached rigidly.

"What we've done is sever the hierarchy at the elbows and the knees, so that you put the foot where you want, it will worry about the leg later, and move the body along. You have to be careful to get the effect that you want, but you're basically unlimited in what you can do. It's not like you're moving a model around at that point. The difference between using heirarchy and our software is like the difference between armature animation and George Pal's Puppetoons. Those Puppetoons had that great look to them because they're doing replacement animation on the character. But if you're just using a hierarchal choreographer, it's like armature animation. Like King Kong."

Animation Magazine: published by Thoren Publications, Agoura Hills, CA (818) 991-2884.