Sonny follows in the digital footsteps of Gollum. Actor Alan Tudyk’s performance is featured in 80% of Sonny’s screen time. Photo Credit: Digital Domain.

Walking In Gollum’s Footsteps
Plate photography of the robot scenes required a minimum of four passes in order to provide the necessary elements. In a typical Sonny shot, the crew first photographed Will Smith playing the scene with actor Alan Tudyk — completely dressed up in green — as the robot. Then, Smith repeated his performance without Tudyk. The third pass featured a full-size Sonny puppet — built by Patrick Tatopoulos Design — that was moved around the set on a dolly as a light and texture reference. The final pass was a clean backgound plate of the empty set.

“Alan’s performance gave us the outline of what Sonny should be doing, which is a similar technique to the one that was used for Gollum in the Lord of the Rings movies,” Jones comments. “Initially, the plan was to use his performance as a guide to animate our CG Sonny and integrate the character in the plate in which Will Smith had been shot alone. However, it turned out that the actors’ performance was often better in the plates featuring Alan: the intensity was there, the eyelines were correct… It was obvious that the scene worked better whenever Alan had been part of the action. As a result, about 80% of the Sonny shots ended up being Tudyk plates, which implied painting him out in more than 200 shots. It was an enormous task, especially since the plates had been photographed without motion control. In tracking shots, the parallax on the background wouldn’t match, which made it extremely complicated to copy background elements from the clean plate.”

Will Smith’s scenes were shot with and without actor Tudyk. Next, a full-size Sonny puppet was shot for lighting and texture reference, and finally an empty set for a clean background plate was photographed. Photo Credit: Digital Domain.

The obvious solution to animate Sonny was to simply rotoscope Tudyk’s performance, but Jones opted instead for motion capture. Proyas had made it clear that the animators were free to alter Tudyk’s body language as long as his facial expressions would be faithfully reproduced. Given that the robots had many walking and running scenes, keyframe animation wasn’t even considered. “Most people think that animating a walk cycle is easy but the opposite is true,” Jones remarks. “There’s so much detail in the way that we walk. It takes forever to keyframe it and still, you never get it quite right. With motion capture, you’re 95% there. It actually takes the pain away from key-framing a walk cycle and gives you time to focus on the more creative aspect of the animation.”

Capturing the Action
Motion capture duties were handled by Motion Analysis Studios with Scott Gagain, vp of project development, and Jeff Swanty, head of production, coordinating the effort. Once the live-action set of a scene was mapped up on the MoCap stage, actors performed the robots action, up to four at a time, covered up with 48 tracking markers each. Since live action had been shot without motion control, camera angles were matched by eye while the actors tried to mimic what they had done during principal photography. Performances were captured by 22 cameras and applied to CG skeletons by a series of proprietary software. “We had two monitors side by side, one playing back the live-action plate and another one playing the motion capture animation,” Jones explains. “It allowed us to time the performances and get the best possible match in terms of framing and action.”