Hulk was feeling to create a "Greek tragedy" with comic book styling memory montages to the superhero himself, arguably one of the most successful digital humans to star in a feature film.

at the beginning that he wanted this to look like a movie, not like it was real,"Dennis Muren Industrial Light & Magic

69 technical artists, 41 animators, 35 compositors, 10 muscle animators, nine computer graphic modellers, eight supervisors, six skin painters, five motion capture wranglers and three art directors spent 18 months creating the 1,165 muscle shapes for the Hulk.

By using a pose-based system in which shapes were invoked by joint position and rotation, the creature-development team at ILM created Hulk's muscles.

ith the procedurally generated pore and wrinkle patterns.

When Banner transforms into the Hulk, his body grows, his skin expands to accommodate the muscles bulging underneath, and he turns green. Rather than animate the expanding muscles by hand and then using simulation to stretch the skin, the team decided to sculpt shapes to gain greater control. To do this, they built geometry for individual poses based on joint rotations. "For some joints, like his fingers, we could get away with a shape or two," says Ferguson, "but we had to sculpt 42 poses for each shoulder." Using height and spin values derived from joint position and rotation, an in-house program calculated the percentage of various shapes needed to make Hulk's form match his movement. Similarly, the shapes from one model size would blend into another during Banner's transformation into the Hulk and from one sized Hulk to another. The resulting shapes, in turn, determined how the skin looked.

"The values from the shape curves gave the technical director an indicator, on a point-by-point basis, of what percentage of a shape is Banner and what percentage is Hulk," says Gutschmidt. These values were sent to a shader that would, in effect, mix the skin maps using the appropriate percentage of Banner skin and Hulk skin. A so-called "riverbed" texture on top completed the illusion that the transformation happened at a cellular level. "We wanted Hulk to flow into Banner, not fade in," he says.

All these efforts helped make Hulk's skin look realistic. To make it move realistically, creature developers created 62 springs, jiggle muscles if you will, that reacted to dynamics. When the Hulk ran, for example, these jiggle muscles helped the skin flex on his legs. Lastly, the creature developers used a technique called "skin relaxation" to make the skin look like it was stretching and sliding properly. "If you don't separate the texture and the form, it's real easy to get a rubber-suit look," says Ferguson.

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