Flying reindeer: for Fred Claus, Cinesite sends Santa's brother to the North Pole.(CG Modeling)

You might be able to buy the premise of the film Fred Claus, that Santa has a scallywag of an older brother named Fred (Vince Vaughn), but no Christmas comedy would be complete without reindeer, Santa's sleigh, and elves.

A crew of approximately 35 people at Cinesite spent about a year helping Santa's reindeer pull a sleigh from Chicago to the North Pole and applying visual effects wizardry to one of his elves. Originally, seven real reindeer on the set were going to pull the sleigh, but it was too heavy. "It was the size of an SUV," says visual effects supervisor Simon Stanley-Clamp. "And the base was made from cast iron so it was strong enough to be thrown around on a gimbal. It took 10 of us to move it around the set."

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Those real reindeer, however, provided great reference for modelers working in Autodesk's Maya and Mudbox to build their digital clones. Groomers clumped the reindeer's matted fur in the front and folded the hair around their leather harness straps by using painted weight maps.

For rigging and animation reference, the crew traveled to a reindeer farm to see the animals on the hoof. But, to fly digital reindeer past Chicago rooftops, they watched videotapes of swimming horses. "The horses pull themselves through the water by stretching out their legs," Stanley-Clamp says. As a result, riggers devised a system that allowed the digital reindeer to overextend their front and rear legs.

"Initially, we blocked out their flight path using simple splines to get a sign-off on direction and speed," Stanley-Clamp says. "Then we roughed-up the animation so it wouldn't look like they were on a roller coaster. As well as moving the sleigh, they needed to have their own movement." Riggers arranged the gear that hitched the reindeer to each other and to the sleigh so that the animals could bank and turn while staying in formation, and procedural animation moved the hitching gear appropriately.

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