Motion-capture supervisor Jeff Light directs the motion-capture action for the droids, with James Tooley in the motion-capture suit. Photo credit: David Owen.

Apparently there was a whole other behind-the-scenes battle going on between the clones and the droids in Star Wars Episode II: Attack of the Clones -- the battle over motion-capture complexity. The clones won that one, too, given the extraordinary demands of these goose-stepping warriors that, unlike the droids, aren't supposed to look computer-generated.

The Problem With Clones...
"The battle droids involved pretty routine cycles, but we wanted a dead-on live-action, second unit style of shooting for the clones," explains Jeff Light, Industrial Light & Magic's motion-capture supervisor. The training sequence in which we are first introduced to the clones in Episode II took seven weeks to animate. Here the clones put on their helmets, march in formation and snap to attention. It was actually more demanding than the thrilling arena battle sequence, according to Light. "There were different orderly groups interacting during the formation session. It was a real organizational challenge.

"For every take in motion-capture, Sylvia Wong [the animation lead] would find an extra human move or would hand adjust to animate on top of the performance. But we were careful not to change a performance with keyframe animation. If the performance had to be changed, we would do another session."

Front to back: Jeff Light, James Tooley and Michael Sanders on the motion-capture stage. Photo credit: David Owen.

Working with Wong, Light would get the motion-capture performance he needed in the studio and then deliver data as a moving cloud of points. "I had a team apply data to the characters," Light says. "After tweaking the performance, data was fit into a library and then the translation rotation was run through space, which Sylvia placed along a path."

The realistic look of the clones was achieved as a result of advances in the Vicon 8 optical motion-capture system (previously used in Episode 1) and an improved pipeline for ILM. The 20-camera high-res set-up (as opposed to the earlier 7-camera low-res set-up) provided more bit depth, which allowed the animators to cover every angle in real-time to see how a person relates to his environment.

"There have been a lot of advances in motion-capture," Light adds. "It's a lot faster and more sophisticated -- you can visualize much better and dial a performance based on mood more exactly."

This occurred, for instance, when George Lucas instructed them to dial a much harder snap. Interestingly, James Tooley, the technical animation lead with a military background, suggested a stylized, Gestapo-like move that Lucas approved.

"I played a clone during one of the motion-capture sessions, which was later replicated 100 times, so you could say that they cloned me," Tooley jokes. "The labeling and triangulating trajectories of motion-capture points were better in Episode II, which meant the volume of work was more efficient."