A View from Kate Greene
The Special Effects of Benjamin Button
A new type of motion-capture system tracks facial expressions.
At the Academy Awards last week, the Oscar for visual effects went to the team behind The Curious Case of Benjamin Button. The movie was a special-effects success thanks, in part, to a company called MOVA and its novel motion-capture system.
Motion-capture systems track actors’ movements and allow those movements to be animated using computer-generated characters. The technology has come a long way in the past decade, but many of the systems used for movie making require a human actor to wear hundreds of reflectors, so they are limited to sensing large movements of the body, not subtle details in a facial expression.
However, MOVA’s technology, employed in Benjamin Button along with other technologies, uses a glow-in-the-dark powder that can reveal tiny details like laugh lines or a furrowed brow. In a studio, MOVA’s system uses an array of cameras to film an actor’s facial expressions while the lighting alternates between light and dark at a rate of 100 times per second. The video is then sent to a computer where the glow-in-the-dark tracking points on the actor’s face are used to create a three-dimensional digital version of her face. Because the powder can’t be used in the eyes and mouth, digital engineers add them afterward.