"Cats & Dogs was our first talking animal movie and now it's the mainstay of the business," remarks Blair Clark , the visual effects supervisor from Tippett. "We had to get Kitty Galore because not only is she a great character but she was going to be hard and push us in ways we haven't quite explored yet."
Indeed, the villainous Sphinx, Kitty Galore (voiced by Bette Midler as Carol Burnett doing Nora Desmond), represents everything that Tippett has struggled to conquer in a cat, and Clark says they're the stronger for tackling her.
"She's got all exposed skin and all the wrinkles and bones that you could hide under the fur before," Clark suggests. "But now we don't have anything to mask that stuff: how the joints appear and disappear out of this big bag of skin.
As noted in "Twilight Experiences an Eclipse,"  Tippett developed a new fur growth system for Kitty Galore that was leveraged on the latest Twilight sequel, in which replaced the black-and-white map technique with a node-based system that works more like a compositing package. Tippett can build a node-based tree that determines how much fur is grown by calculating length, width and curliness.
However, even though Kitty is basically "hairless," there is a layer of peach fuzz that covers her skin as well as short hair on her nose and long hair on her legs and tail.
"We found that when you just did skin, it didn't look right," Clark continues. "You'd have the subsurface scattering and translucency to the skin, but we had to grow peach fuzz all over her anyway. It needed that to bring it to life.
"We also had to pay close attention to the clavicle and shoulders, especially with these cats because they have to be quadruped. Kitty always talks about the Call of the Wild and raises her arms. Her armpits caused problems and we asked a lot of the model and rigging guys to have her get down on all fours and raise her arms over her head."
Meanwhile, Imageworks concentrated on the two lead dogs, Diggs (James Marsden) and Butch (Nick Nolte), as well as the feline Catherine (Christine Applegate). Imageworks also shared assets for Catherine and the pigeon Seamus (Katt Williams). Overall, Imageworks created about 500 shots, evenly split between CG characters and face replacements of real animals.
Like Tippett, Imageworks played to its existing animation strengths. "I found Catherine to be the most difficult because of how hard it is to capture the skin surface and skeletal placement accurately due to the fur," Hoover suggests. "We did our usual extensive acquisition of the character with multiple still cameras, almost a 360-degree view at the same instant. But it's difficult to accurately see where their skin is. We measured the hair dab in several places in the body and accomplished what we needed.
Imageworks also had two notable action sequences: Butch chases Seamus over San Francisco with Diggs on his back and a CG James Bond-like apparatus strapped to him, and the climax in an amusement park, which features a CG apparatus that unfolds and becomes Kitty's secret weapon and contains CG animals climbing all over it and chasing each other.
"We built a 2.5D, 360-degree environment of the theme park so that Brad could direct any kind of camera move he wanted as that action occurred," Hoover adds.
Hoover says "the biggest challenge in this kind of movie always is the requirements of the character: How much actual departure from a real character is there? And is that the kind of movie the filmmakers want to make? In this case, we folded back and forth between quadruped dogs and cats and anthropomorphizing them to do things that an animal wouldn't do. And then the normal requirement to make a CG character that can cut back and forth with a real animal."
Bill Desowitz is senior editor of AWN & VFXWorld.