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Animal Research To get a handle on how wolves actually look, move, and react, leads from modeling, anima- tion, painting, lighting, and so forth took a fi eld trip to Wolf Mountain Sanctuary in Cali- fornia, where the team was able to observe, in- teract with, fi lm, and document the animals. "I was surprised at just how big a real wolf is," says Jacobs, who estimates the real animals at about 170 pounds. Jacobs notes that the group learned a good deal about the wolves' motions, what their fur looks like, and some of their subtle manner- isms, all of which the animators tried to incor- porate into the performances of the digital ani- mals. " e wolves we created weren't supposed to be wild," he explains. " ey had to perform and do things maybe wild wolves wouldn't do at times, but we still tried to draw on what we had learned and observed, to bring more real- ism to their performances." According to Tom Gibbons, animation supervisor, one of the big tasks for him and his team was to create wolves that represented the natural world but also had a touch of the human character as portrayed by the actor in that role. " e Jacob wolf would have a bit of the Jacob personality, the Paul wolf would have a bit of Paul, and the Sam wolf would refl ect some of that character," he says. "Where to fi nesse those lines was a big challenge for us. ose three characters were the most person- ality-driven in this story. We looked at the ac- tors' performances and sussed out how to put that into a naturalistic wolf and not break the illusion that it was a real wolf." Preparing the Pack e modelers, lead by Jack Kim, used ortho- graphic images collected from the fi eld trip and from books and other sources as model references. ey also purchased a taxidermy "blank" to obtain accurate information about the animal's underlying structure beneath the thick coat—a reference that proved especially benefi cial, says Jacobs. Using Autodesk's Maya, the artists built the surface model for the wolf, focusing on cre- ating it to the accurate scale and proportion of a real wolf, and used Autodesk's Mudbox for displacement sculpting. ey then slightly altered the model for each subsequent wolf, such as the length of the snout and ears. Next, Kim populated the model with ap- proximately 4000 splines to achieve the overall shape and base length of the fur. Afterward, the model was sent to the paint department, where the fur was styled and groomed using Tippett's new in-house fur tool, Furator, which interpolates all the hairs on the character using the shape of nearby curves to infl uence the look of the in-between curves. With Furator's node graph, the artist assigned to the project added secondary and tertiary de- tails to the fur in terms of the length, scale, ro- tation, elevation, scraggle, clumping … all the features that give it "character." (An accompa- nying story about the creation and capabilities of Furator can be found on, under Web Exclusives.) As Fredenburg explains, the painter had to give the fur diff erent qualities literally from the nose to the tail. "We had to come up with a plan to integrate all the diff erent types of hair and be able to deal with diff erent look issues on various parts of the body," he says. For instance, the muzzle was fairly straight- forward, with short hair that the artists then mussed up so it would not be computer per- fect. On the belly, the fur was clumped and long; on the back, medium length. On the tail, the fur was big and bushy; on the feet, short and velvety. e biggest challenge was at the neck, where the velvety, short fur on the muzzle quickly be- comes long and mane-like on the cheeks and the chops, those pointy tufts of fur that extend from the cheeks and give them their iconic wolf look. "We spent a lot of time, probably more than we wanted to, getting the shape," says Fredenburg. Achieving that recognizable attribute re- quired a great deal of back and forth between paint and modeling, whereby the modelers would reshape the splines to refi ne the look, and the painter would break up the splines with clumping and scraggle. " e painter would rotate the hairs, elevate them, and clump them together on these animals, which have very dense fur coats that tend to get mat- ted," says Fredenburg. Built by Mike Farnsworth and Andrew Gardner and used fi rst for Cats & Dogs 2 (still in production), Furator enables artists to put together large sets of operations—for instance, loading the geometry and fur, interpolating the fur, applying a length modifi cation, scraggle, and clump, merging fur, splitting fur—and store it as a project that, at runtime, generates the fi nal look of the coat. e project exports as caches with huge amounts of fur in them; the caches are then rendered in Pixar's Render- Man, though the tool is renderer agnostic. Two other painters incorporated the color variations on each hair. is varia- tion had to be carried out on all fi ve of the wolves: Jacob, which was rust brown; Sam, black; Paul, gray; Jared, chocolate brown; and Embry, lighter gray. " ey had to work collaboratively. One complicated thing about wolves is they have very unique color ticking down the length of the hair that contributes to its patterning," says Fredenburg. "We just couldn't paint the regions of color; we had to build up the pat- terning by working the color down the length of each individual hair." RenderMan shaders created in-house en- abled the painters to apply color to the root, the midsection, and tip of the hair. A map lets them control where the blend occurs between those areas. " e painters would basically paint three versions of the coloration of the wolf and blend them down the hair with these mix maps," explains Fredenburg. December 2009 39 CG Animals ■ ■ ■ ■ Key to generating the realistic fur was achieving various qualities and looks across the animals' bodies— for instance, short hair on the muzzles and big, bushy fur on the tails. Also, the painters had to incorporate color ticking down the length of each hair on all the wolves, a process achieved using RenderMan shaders written in-house.

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