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Galactic News
Friday May 2, 2003
Homing Beacon #84 |
The latest Homing Beacon has arrived, and today we get to talk CG
hair. It wasn't entirely by accident that most of the
computer-generated characters from Episode I had smooth amphibious
skin or hard metal finishes. When it comes to unmanageable hair, the
digital variety has the most kinks to work out. The workload of
Episode I favored hairless subjects, as did Episode II, though the
digital creations in Attack of the Clones did feature a few
exceptions: Yoda had a hazy crown of wispy white hair, and the
digital doubles of the main characters had to be as stylishly
coiffed as the actors who played them.
"With the digital doubles, you have less hair than you would a
furry creature, but it has to be specific hair," says Steve
Sullivan, Research and Development Director from ILM. "You're
actually trying to match a given actor, so the artist needs to be
very precise in the parameters."
Some of the Industrial Light & Magic's early experimentations
with digital hair were with creatures in Jumanji and The
Flintstones. Just getting a computer to recreate the thousands of
individual strands was a milestone, but teaching it how to move was
a different challenge altogether.
"For the lion in Jumanji, it was very complicated to have
something as dense as a mane. There is no way an individual artist
could control all the hairs directly, so they went with an approach
with 'hero hairs' or 'guide hairs.' An artist would animate those
and place them carefully, and then the computer would generate all
the stuff in between. So, the hair colors, densities, lengths and so
on were generated by the computer, but very much controlled by the
person. These hairs didn't react at all to the environment or the
motion of the lion, so somebody had to animate them by hand,"
says Sullivan.
The proper interaction of the hair with the underlying digital model
is now handled by dynamic physics simulation, the same complex
computations used to properly recreate the folds and drape of
digital clothing and the hundreds of fragments of crashing
Podracers. Now, the digital hair reacts as it would to real wind,
gravity, and motion, without having to be continually managed by an
animator. Still, the task is not that easy.
"The current approach is like this: say you wanted to comb your
hair," explains Sullivan. "You'd look in the mirror, turn
off the light, try and comb it, wait a few hours, turn on the light
again, and see how it looks. It's very indirect and very painful,
and that's what the artists who do this kind of work have to deal
with. We have a long way to go still, and our mission is to try and
make it as simple as possible. You can imagine what a hair system
should be like. It should be easy. Your mom should be able to use
one of these systems, but it's going to be years till we get to that
stage."
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Posted:
by Jedi
Power
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