"The solution," he says," was a combination of things: a lot of effort in grooming to alleviate where we knew where the feathers were going to intersect, and a lot of iterations. We constantly did test renders. We have an automated rendering pipeline where we can send assets through from any part of the process a test with as much context as we want. If an artist wants to see how their textures look or how their groom looks, they can set up an automatic render that will send them a shot back with the correct lighting."

Although the Animal Logic team still used Softimage and Maya, they created a lot of new proprietary grooming and shading tools to meet the demands. "We did further computing for the collision and simplified models for the characters that were rigged for character to character collision. Also, we did dynamic simulations for wind effects and generated particles off the feather locations for sticking snow particles onto the characters or for interacting with rain, clouds and fire."

Since owls have beautiful large eyes, to enable them to see in the dark, they can't move, they are locked in their heads, which proved to be a further challenge. "The art department wanted to keep the depth and refraction of these eyes as well, since it is something so iconic to owls," explains Weight. "So we tried some test animations with the eyes completely locked off. Any eye dart became a head dart. But we found it made the character too detached, too much of a creature and therefore unable to be connected to by the audience. Plus, the eyes are such a large playing piece when it comes to conveying emotion that we were robbing ourselves of too much."

For Leighton, the biggest challenge was maintaining the continuity of performance through a very substantial series of story adjustments throughout production. "We ended up shooting a great deal more than what you'll see on screen," he reveals. In fact, Warner Bros. pressured Snyder to omit a very intense sequence early on reminiscent of The Searchers, ironically, because the studio thought the darkness came too early and there hadn't been a break for the kids in a while. Fortunately, Snyder says the sequence will be viewable on the Blu-ray/DVD.

"It was a central moment, and it was the most emotionally powerful scene that we shot, by far; and it was difficult for us to get out of that zone because it is the thing that propelled the rest of the story," Leighton insists. "It created a great conflict and certainly a great motivation for Soren to make amends. It became quite a challenge to wrap our heads around such an omission and maintain character performances without it. Arcs, relationships and subtexts were altered significantly. Right up through the last weeks of animation we had to keep up with that and keep everything integral. Once you get into the heat of production and plans change, then, unfortunately, what happens is your ideal casting choices and shooting sequences get thrown out. So you wind up casting people on characters that might not be their forte and you have to shoot things much more dramatically out of sequence. You're trying to manage a balance of a shifting dynamic and shifting story while you're shooting checker-boarded the entire thing at the same time."

Still, Leighton says that in almost every case the animators willing to embrace a more physical way of performing ended up showing the most improvement. And the Guardians was the better for it.

Bill Desowitz is senior editor of AWN & VFXWorld.