Computer Graphics World

July 2009 50 n n n n CG I "We can shape, sculpt, stretch, squash a character almost any way we want, which allows us to get close to what 2D anima- tors have been doing for decades." e rigs have blendshapes built in, but much of the shaping happens through the joint sys- tems, which allow the animators to freely push and pull parts of the geometry. For example, although Scratte shares some of the characteristics of the irrepress- ible, acorn-obsessed Scrat, she has a distinct personality—actually, personalities, plural— and the rig helped animators accent those personalities. We don't know whether her goal is to have Scrat fall in love with her or to steal the acorn. "Scrat's instinctual," says Gabor. "She's a slicker, sexier, smarter ver- sion of him, and she uses intelligence and sweetness to get the acorn. So it becomes a love triangle: Scratte, Scrat, and the acorn." When Scratte is acting sexy, the animators used the flexible rig to sculpt her body with a small waist and a big chest and butt. When she's acting cute and innocent, they give her more of a potato shape, like Scrat. Scratte's dual personalities and Blue Sky's flexible rigging meant that it was particular- ly easy for the animators to slip off model. "at's the downfall of having so much control," Gabor says. "She was especially difficult to keep on model. We needed to keep her looking seductive, and a lot of min- ute details affected her appeal. It was easy to make her look ugly if we weren't careful." One trick was to keep her mouth closed. "When she opens her mouth, she looks like a coyote, so almost 90 percent of the time she doesn't open her mouth," Gabor says. "Scrat, on the other hand, the uglier he is, the more pathetic he is." Twisted Fate Animators working with Buck also needed to be careful to keep the weasel appeal- ing. To make Buck look like an untamed animal, the character designers gave him long, sharp teeth and a patch over one eye. "We'd pose his mouth and teeth to give him a wilder look," Dastrup says. "Buck is trapped in a lost world filled with dino- saurs, and the isolation has driven him a bit crazy. He's a survivor, but he's a bit de- lusional. He might hear a rock calling him, or a bush. But, he's a lot of fun, and he risks his life to save Sid." Buck has a long, weasely spine, so Dastrup and the 10 animators working with him benefited from the rig's agility, performing some extreme animation. "Buck used his spine to his advantage, to move around in a dangerous world," Dastrup points out. "e animators would twist him, tie him up, wrap him around things, and use the rig in a way that was a lot of fun." Gabor points to a particularly awesome shot: "ey twisted him 360 degrees, like a towel squeezing out water." Dastrup elaborates. "Buck is coming out of the water when we first see him," he says. "To wring himself out, we twist his body 720 degrees, as if we were wringing a towel, and then he jumps in the air and dives down, like a missile in a corkscrew spiral, to get inside a flower. ree hundred and sixty degrees wasn't fun enough." Although the animators had controls and ways to clean up any crashing geometry resulting from all that twisting and wrap- ping, it wasn't often necessary. "e spine rig handled a lot," Gabor says. "We could stretch him, create a C shape, and even cre- ate an E shape. We're pushing the CG art form and trying to go as far as traditional animation has gone. I think everyone was pleased with how well it worked." At the peak of production, nearly 70 ani- mators worked on the film, with about half hired temporarily. "We have a lot of teach- ers at Animation Mentor," says Gabor, "so we draw from the students there. For the most part, the people we hire are pretty close to just out of school—on their first or second job. Or, they are going through a career change and trying to get into the animation industry. We train them for two weeks, and they're on their way." To help the animators, character leads create pages with dos and don'ts for each character. And, animators often sketch out poses using a 2D program developed in-house. "Animators use it to pitch ideas, plan shots, and brainstorm," Gabor says. "It's like a light box—you can see the drawings underneath and flip through them to see them in the context of shots around them. You can also take them into [Autodesk's] Maya and use them as an underlying structure for animation." Ani- mators also videotaped themselves for act- ing reference and sometimes even showed directors that footage to get an OK for a performance idea. Animators took advantage of Blue Sky Studios' flexible rig to twist the one-eyed Buck's CG body into shapes rivaling those of hand-drawn animated characters.

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