Rhythm & Hues has become a digital Animal Farm with its animated virtual menageries. The studio created 500 CG shots for Alvin and the Chipmunks. All images ™& ©2007 Twentieth Century Fox and Regency Enterprises.

At the LA-based visual effects shop Rhythm & Hues, the "cute critter quotient" runs pretty high. Following R&H's Oscar-winning visual effects in Babe, the studio has animated virtual menageries for Mousehunt, Charlotte's Web, The Chronicles of Narnia: The Lion, the Witch and the Wardrobe and The Golden Compass. The veteran animation team also has created fanciful animal characters for Scooby-Doo and Garfield, so when Garfield director Tim Hill took on Alvin and the Chipmunks for 20th Century Fox Animation (opening Dec. 14), R&H was a natural choice to create 500 CG shots that the show required.

Todd Shifflett, who has worked on several of the shop's critter features, including Charlotte's Web and both of the Babe and Scooby-Doo movies, brought an experienced eye to the post of visual effects supervisor on Alvin and the Chipmunks. "This is the first time they've been animated in 3D," says Shifflett about the chipmunk trio of Alvin, Simon and Theodore that's famous for singing their perennially popular Christmas song. "The director wanted them to look like real creatures but not necessarily actual chipmunks. They're chipmunk-esque," he laughs.

The R&H team spent considerable time poring over the extensive archive of 2D material that's been amassed since Alvin and the Chipmunks debuted a half-century ago. Shifflett recalls, "There is a lot more than you might think. There was an episodic television show for children that ran for a long time, and they had versions in different countries. So it's been running pretty steadily for the last 50 years. The biggest usefulness of doing that research was to understand how each of the characters would react differently to different situations."

Translating well-known 2D cartoons into 3D required more than adding dimensionality and realistic fur. "These are quite a bit different than the 2D characters, which were the size of children," notes Shifflett. "It would have been a little too creepy to see giant furry things running around. Our chipmunks are probably three times actual size. There was certainly room to develop a different look.

"The most difficult part was establishing what they were actually going to look like. We went through a number of iterations -- beginning with something that looked like it came right out of the woods and had a much more realistic fur quality to it. But that was just a little too scruffy and not enough like a 'Hollywood movie star.' Yet if we pushed the look too far in the other direction, it started to seem just too cleaned up and too much like a stuffed animal. So trying to find a middle area that everyone was happy with was probably one of the biggest hurdles.

R&H took months to shape the characters. They examined features like the size of the chipmunks' heads, the placement of the eye and the color of their fur.

"The process of shaping the characters took months," Shifflett explains. "We went through everything from how big their heads were to where their eyes were placed. Then we had to establish how light or dark their fur would be. When you talk about an animal's fur color it's complicated, because there are deeper layers of fur -- there's an under pelt that contributes quite a bit to the fur's look, which you don't necessarily latch onto right away. If you make the under pelt dark and the outer pelt light, you get a totally different look than if you do it the other way around. There are lots of variations that have to be mulled over. Even when we look at an animal that we would consider being a solid color, there's actually quite a bit of variation. It's something that if you actually make it only color, you start to get a cartoony feel."

R&H used the same fur simulation tools that were employed to create the photorealistic lion in Narnia, and Shifflett explains that fur sims were run for Alvin and the Chipmunks. "Each character had to have a distinct hairdo built for it, and we were given some latitude in certain scenes when they get really excited. For example, if they're riding on the top of a remote-controlled car, we could blow the fur around."

Of course, real animals don't ride on toy cars, so R&H had to finesse variations on actual chipmunk behavior when creating the character animation. Shifflett recalls observing the behavior of real chipmunks as part of the research for the film. "Universal Studios has some chipmunks, and they were kind enough to allow us to come over and spend some time videotaping the animals. It was pretty fascinating to get up close and personal with real chipmunks. They're tiny and they move very quickly. We got them running to see how their muscles move and we could get a good sense of how their fur was combed and what their little mannerisms were like when they were standing and twitching."

While the behaviors of Alvin and the Chipmunks were stylized, Shifflett says that they were "dialed down a notch" from cartoon animation. "We did have the latitude to push the characters' expressions, but the director did want some naturalistic motion to make them feel like they were really in the environment." R&H used its proprietary software Voodoo to handle all the animation, which included animating the clothing that the chipmunks wear. "There were certainly some technical challenges, for example, in trying to make their sweaters look real. It's complicated when you stretch a sweater -- you don't want it to look like texture mapping. You want to make it feel like the actual cable knit is stretching."