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.com VIDEO: Go to "Extras" in the November/December 2013 issue box ©2013 Summit Entertainment. tions. Some shots were fully CG, which removed the problem " of physical reality. For some, they could use live-action shots of the actor. "But more often than not, they photographed Butterfield, and we manipulated the content back into a physically realistic situation, Butler says. "When the actors are in the " middle of the battle room, their center of mass is where it is. In zero gravity, you still have a center of mass – mass and gravity are completely independent. But, you have no weight. And, your center of mass cannot move without force. What it means is that the actor's pivot point should be at a fixed point in space, not a fixed point on the body. There's no point on the body that is a pivot point. But, we still have the same inertia; Newtonian physics still applies, and we had to abide by all those rules. " On set, Warren had rigged wires and armatures to move Butterfield. "In tight shots when you couldn't see anything other than his head and shoulders, he was on a bicycle seat on an ar- ■ DIGITAL DOMAIN corrected footage of actors on set to give the correct pivot point for movement in zero gravity. mature, Butler says. "If he needed to leap, Garret would move " him on wires. The problem is that penduluming is a function of gravity, so it was hard to move him at a constant speed. " The stunt coordinator also put Butterfield in a tuning-fork-like apparatus that held him at the waist, and used a dual-axis harness to rotate him. "But again, it didn't allow for a correct pivot point, Butler says. "We did our best, and then we'd get back " to the ranch here, to Digital Domain, copy what we photographed, and look at what was wrong with it. " Pivot Point The first step was to move the actors in the footage as much as they could to try to approximate zero gravity. Next, they roto- NEXT ISSUE These are some of the exciting topics that will be covered in the January/February issue of Computer Graphics World magazine GAMING: A new standard for graphics in games COMPUTER GRAPHICS WORLD MODELING EVOLUTION: Blending science and art to create Jurassic models FANTASY CREATURES: Challenges in modeling, simulation, and animation for The Hobbit: The Desolation of Smaug SHORT AND SWEET: Techniques that raise the bar for CG in short films STORAGE: The state of storage in the studio …AND MORE CONTACT YOUR SALES REP FOR MORE DETAILS. Mari Kohn, Director of Sales 818.291.1153 or mkohn@copcomm.com Lisa Black, Corporate Marketing & Advertising Sales Executive 818-660-5828 or lblack@copcomm.com C G W N ove mb e r / D e c e mb e r 2 013 ■ 19