Check out the abs on that guy.

Building the Perfect Hulk
"Humans are most difficult to animate," Brady explains, "because we see them every day and our eyes are most critical to texture, muscle and movement. A two-year-old can discern very well what's real and what's fake. We started by studying a lot of anatomy, bringing in body builders. We initially thought we were going to be able to sculpt each target pose so well that the Hulk would be more or less automated. We even discussed building from the skeleton out and all the muscle and skin on top of that. The human body is so complicated that you can't really build a model that's going to work for every single pose. We had a task force of shape guys that were anatomy checkers. Animators would give them the first pass and these guys, many of whom are artists and sculptors, would clean up key frames and make sure bone protrudes from the right place and muscles flex where they’re supposed to. We were given a design and model that were predetermined and the Hulk was already pretty exaggerated. You had to take some liberty with anatomy."

Perhaps the most remarkable sequence in the film is the dog fight in the forest, in which the Hulk must protect Betty from some savage beasts that have been imbued with some of his supernatural powers. "Early on, Ang proposed having the Hulk be nude during the dogfight, and I was all for it," Brady says. In many ways, the dogfight is the most primal moment. In my view, it's all about Hulk's adolescence, and Ang would really talk about the Hulk's three stages of development. First there's the 9-foot baby Hulk in the lab; then there's the 12-foot medium-sized Hulk in the forest; and the fully grown 15-foot Hulk who's in control at the end."

Although it was a nice idea in theory, it wasn't very practical for the Hulk to be nude in the forest in a PG-13 film. Brady said it started to look like an Austin Powers scene because of the way they had to carefully place dogs or trees in front of the Hulk's naked body. The last thing they wanted was unintentional laughter. Not when you're dealing with a man-child haunted by memories of his parents arguing behind a door.

Being a superhero is dirty business.

'Muscle Relaxation' Technique Helps Empower Hulk
Despite criticism from the animation community that the Hulk is not convincingly animated (do we still have too much Gollum on the brain?), Brady is most pleased with the facial performance. " For me the biggest surprise is that people make a greater connection between Hulk and Eric than we thought. No one seems to question that this Hulk is Eric." He attributes this to Lee's direction. In fact, in the San Francisco climax, Lee specifically told everyone to reference Kevin Kline in The Ice Storm. " At the very end, Kline has turned around to his family and realizes all the problems his lifestyle has caused and starts to tear up, and Ang wanted to capture that moment right before somebody cries. He didn't want Hulk to cry but talked about a tightness between the eyes and so we would reference that stuff frame by frame, even the little twitch and tightness that happened around the mouth. So you could say there's even a little Kevin Kline in there as well."

In terms of animation, there was some sub surface scattering done to create a certain kind of translucent quality to the skin and ears. ILM utilized a technique called "muscle relaxation" that provided a greater sense of skin sliding over bone and muscle "so that you're able to move the texture of the skin over a muscle surface while retaining the shape of the muscle underneath."

Skin traveling over mass is one of the biggest technical breakthroughs on the film, according to Brady. "The other one is that for the dog fight sequence we brought in attack dogs and motion captured them. This is the first time dogs have ever been motion captured so well, certainly here. We made goofy motion capture suits for dogs, brought in a dog trainer and had massive [mixtures] fight and take down this guy. In the end 30% of the sequence was performed by real dogs."