In addition, creating a muted palette that pays homage to the Flemish masters was frustrating because of the lack of a decent computer model, according to Armour. "The north facing studio window, the Vermeer look, is what we were going for in a lot of the show. It has very, very soft lighting and as much as possible all of it is motivated. You put a movie light if you need to for separation of backgrounds, the sort of things you would normally do in live action. But the lighting approach was: First, what would the room be lit by? Where are the windows? What kind of day is it outside? And weather is a very important story point: going from a very bright, salutary beginning to a grim, very gray, monotonous feeling in the middle of the film, going into a storm, which clears to, again, a bright, sunny, positive scene. And all the interiors of mouse world are lit indirectly from windows. And rat world is sort of lit like a city at night with local sources.

Creating a muted palette that pays homage to the Flemish masters was frustrating because of the lack of a decent computer model.

"One of the first things I looked at after coming up with new surfacing tools was more image-based lighting models to reflect the environment more. It didn't start out that way: it was more like a vfx project where the background plate was supplied in one sense and you had to light the characters separately. And the only way I could see getting through this was to light the characters with the same lights as the ones used for the sets.

"Coming from a photographic background, I start out trying to emulate the same ratios of brightness that you'd encounter on a real set. So, if there's a window light, whatever's out there would look bright enough to light the interior of the set: 5 stops up from a gray sphere in the back of the room. So we would start out doing some indirect diffuse lighting setups and then from that derive one or more reasonable environment maps. And the room lighting would fall together pretty well just from the indirect diffuse and the derived environment map. And then the individual character lighting would be done by generating local environment maps where the characters were. If they were moving around a lot, we had to come up with alternatives. And there might have to be an array of lights to get soft enough shadows.

Dan Smiczek (Night at the Museum, The Chronicles of Narnia: The Lion, the Witch and the Wardrobe) served as effects supervisor and also got his first taste of animation on this movie. " I started out with a small but mixed team. We were split between Maya and Houdini. We took advantage of Houdini 9's fluid simulator instead of Realflow. We did fountains, soup sims, an ocean, piles of potatoes being cut up and sliced. For smoke and steam, we took advantage of Framestore's in-house tool, whisper, an interface with Houdini's volumetric renderer. The biggest R&D was the ocean made of generic water surface shaders because it had to be stylized enough to fit in with the matte paintings. It's a very interesting look: a moody color palette that you don't see in most animated movies. Using Houdini brings the effects up a notch in animation. You can get much more technical and it adds a realistic look."

Smiczek, who has quite a bit of experience with Massive, was instrumental in using the AI-based software for the crowd sequences involving thousands or hundreds of rats in the Coliseum. For more intimate shots of 10-20, Framestore came up with an in-house solution of playing back animation clips."

Now that Framestore has completed its first animated feature, what next? " "We've got a couple of pictures in development that Framestore is trying to do on their own," Lipman offers, "but I think the door is going to open up once people see the picture and understand what we've delivered."

Bill Desowitz is senior editor of VFXWorld and AWN.