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Issue: Volume: 24 Issue: 7 (July 2001)

Fur Real




Digital groomers style a new coat for a panda model

By Audrey Doyle

The commercial is anything but subtle. Footage of various endangered species flashes across the TV screen as Bob Dylan's "Shelter from the Storm" plays in the background. While the announcer explains how viewers can help protect these species by making contributions to the World Wildlife Fund, the scene cuts to a small cluster of bamboo trees, where a panda bear walks across the frame as a large contribution envelope falls to the ground. The bear then takes cover inside the envelope, curls up, and peacefully goes to sleep.

Although the commercial's message is simple and direct, the process of creating the 60-second spot, titled "Panda Bear," was quite the opposite. "Technologically, this was the most challenging project I've worked on," says David Shirk, animation supervisor at Quiet Man, the New York City facility that created the CG spot for The Plowshare Group agency (Stamford, CT). "Even as far as computer graphics technology has come, creating fur in the computer is still a technical hurdle that's larger than any I've dealt with so far in my 15-year career."

According to Shirk, it was impossible for a live panda bear to be used in this commercial. Not only would it have been difficult to train a panda to crawl into a large envelope and pretend to fall asleep, but using the animal in such a way would have been unacceptable to the client. "The World Wildlife Fund has a tremendous amount of sensitivity regarding animals, especially endangered ones," Shirk says. In fact, he adds, this might be why the client and agency asked Quiet Man to model the bear in a slightly stylized fashion, rather than aim for true photorealism.
Modelers created convincing-looking skin and fur to give a panda model a realistic yet slightly stylized appearance for a World Wildlife Fund television commercial.




Although the bear is somewhat stylized, that didn't mean the Quiet Man team could take shortcuts when modeling, texturing, animating, and lighting the animal's pelt. On the contrary, the panda's fur had to be generated so that it moved realistically, as though it were part of the skin to which it was attached. "We've faked fur in the past by using a 2D cheat-essentially, by creating 2D texture maps of fur," Shirk admits. Employing this trick on "Panda Bear" was out of the question, however, because it was necessary for the animal to be viewed from all sides. "He turns completely around in one shot, so there was no way we could use that 2D shortcut," Shirk says. "Plus, the fur had to be an organic part of the character so that viewers would accept it."

Realizing the technical challenges that lay ahead, Shirk and the team first studied reference footage of pandas, then Shirk sketched pandas until he got a sense of how they move, how their musculature works, and how the muscles move under their hide. Next, he built a polygonal model of the panda's skeleton and skin in Avid's Softimage 3D and conducted several animation tests in the software, all the while tweaking the skeleton and skin whenever the character's movement appeared awkward. The animator says it was important that he develop the panda's skeleton and skin simultaneously because the skeleton is what drives the panda's motion, but the interaction between the panda's skeleton and skin defines what viewers see.

"Although I found lots of reference footage of pandas, it was hard to find good zoological references of these animals. Moreover, because bears have a loose skin that slides over their musculature, it's difficult to tell what's going on under the surface. So, I had to animate the character's movement through trial and error," Shirk explains.
In addition to creating realistic fur, the modeler also had to ensure that the pelt and skin moved realistically across the animal's musculature as it lumbered toward the envelope.




"But by developing the skeleton and skin at the same time, I could properly define the muscles and determine how the shoulders move and where I would need more or less geometry," Shirk adds. "I could manipulate the skeleton and see right away when areas of the skin weren't moving correctly. It helped me figure out how much detail I would need, to make sure the skin would work correctly with the skeleton."

Up to this point in the creation process, Shirk had been working with a bald bear. Now that he had the skeleton and skin moving correctly, it was time to texture-map the skin's surface. Although he would eventually be covering the panda's body with 3D fur, first he assigned texture maps of the skin to the entire surface of the model in Soft image 3D.

"The texture maps were necessary to control the various fur parameters," he explains. "I created one texture map that would control the color of the fur, another that would control the length, and a third that would control the thickness."

Assigning these texture maps to large, flat areas of the panda's body-such as its stomach and back-was fairly painless. The limbs, however, proved more challenging. Explains Shirk, "Because a bear is basically a big blob shape in the middle, with limbs growing out of it, it was easier for me to build the model with polygons rather than NURBS. With polygons, though, it was hard to get the texture maps to attach to the polygons in a coherent way, especially on areas where the limbs joined to the body."

Shirk overcame that problem by using Cineframe's YouMap texture-fitting plug-in, which enabled him to create from the polygonal model a NURBS proxy model onto which he could assign UV texture coordinates. "With YouMap, I could work with a NURBS proxy and control how the texture maps wrapped on the surface of the model," he says.

After assigning the texture maps, Shirk painted them using Right Hemisphere's Deep Paint 3D. "It was like painting, using black and white paint, on the skin of a panda bear," he notes. The animator then finessed the painted texture maps in Adobe Systems' Photoshop.
To ensure that the bear's fur moved naturally with its body, the artist first created a polygonal model of the panda's skeleton and skin to help define its muscle structure. Once the skeleton and skin moved correctly, he covered the surface with a




After importing the texture maps back into Softimage, Shirk used various tools with in Phoenix Tools' RealFur to grow, groom, and control the fur. First, he used FurGen to generate a mesh of flat polygons, in which each polygon represented a single hair, and then he adjusted the direction and length of the hairs. "You end up with a simple representation of the fur, but it's enough to show the direction and length that the final fur is going to take," he says.

Next, Shirk used FurSim to specify and control such elements as the fur's mass, friction coefficient, and degree of stiffness. He also used FurComb to groom the hair so that it was facing in the right direction on all parts of the panda's body. "For instance, on the face it should lie back against the muzzle," he adds. When he had achieved a pleasing result, Shirk lit the model in Softimage and rendered it in Mental Images' Mental Ray.

"This commercial represented new ground for us in that we had to create fur in a way we had never done before, which required a lot of experimentation," Shirk says. "But we're already applying what we've learned to new jobs."


Softimage, Avid (www.softimage.com)

RealFur, Phoenix Tools (www.phoenixtools.com)




Audrey Doyle, a contributing editor to Computer Graphics World, is a freelance writer and editor based in Boston. She can be reached at audreyd@mediaone.net.

Images courtesy Quiet Man.
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