Computer Graphics World

January 2009 13 CG Character ■ ■ ■ ■ heads on Pitt's head, but the small actors playing the young Benjamin Button had smaller heads, and Digital Domain's heads would need to fi t on the small actors' shoul- ders. e riggers wanted to give the anima- tors a specifi c facial animation rig for each age. First, though, they did create a scalable rig for the heads to show Fincher various sizes for the diff erent ages. "Once he settled on the scales he wanted," Preeg explains, "we retargeted the motion data, making reasonable guesses for how Benjamin's jaw skin would move when he is 80 and so on. en, we created a rig for each age." It took nine months to put the captured shapes into deformation rigs that anima- tors could manipulate for each age. "Get- ting those shapes into the rig was the magic voodoo," Barba says. And that was only the beginning. Creat- ing a digital human is not easy. Timing is Everything "We discovered that Benjamin not only had to move exactly like Brad does, but without Brad's timing, he wouldn't come across as Brad," Barba says. " ere was no turnkey solution to capture both." at is, to simultaneously capture his expressions and his timing. e plan was to have Fincher direct Pitt reading Benjamin Button's lines on a soundstage after Fincher had fi nished shooting the small-body actors and the rest of the cast on location. e timing Digital Domain needed would come from that reading. "In order to use Mova for that, we would have had to put Brad in green makeup for seven days," Barba says. " at wasn't an option. With Brad in green makeup, it was hard for David [Fincher] to discern his performance." Also, the Mova system wouldn't mix well with the audio recording. " ere are many hard drives," Barba says, "and fans are whirring." Instead, as Pitt read the lines on the soundstage, Digital Domain captured his performance on video. Later, Image Met- rics derived animation curves from that video. "It worked beautifully," Barba says. "Brad was relaxed and gave us a great per- formance. We had him scheduled for 10 days, and he fi nished in seven. He was happy. David was happy." Here's how it worked: Pitt reclined in an ab (exercise) machine on a soundstage, with his knees raised up to align his body. Around him, the crew positioned four ompson Viper digital cameras that were constantly in sync and trained on his face. "His face was always in the center of the frame," Barba says. "And cameras set at angles always gave us his profi le." Although Image Metrics typically uses just one camera, Barba insisted on four. "With one camera, you can't see the jaw from the profi le or subtleties around the eyes and ears," Barba says. Also, Barba wanted to give the animators all four views later for reference. On a nearby monitor, Pitt could see the edited footage from shots fi lmed on location. He wore an earbud to listen to the recorded scenes. "He'd look down, watch the footage, then say, 'Great.' David would call, 'Action,' and he'd do the line," Barba says. " en we'd show him the next clip." Preeg was impressed: "[Pitt] could watch a 40-shot sequence twice and then perform his lines strictly on the audio cues. I was con- cerned about his matching the performance months after the shoot to a person's motion that was done 3000 miles away on set. But, I've got to say that Brad's a lot more than a narrow waist and broad shoulders." After the performance capture and dia- log session, Fincher inserted his selections of Brad's performance into the edited footage, putting the selects on the side of that footage. To turn a performance into motion data, Image Metrics' custom software usually translates key points from a video onto a Instead, as Pitt read the lines on the soundstage, Digital Domain captured his Instead, as Pitt read the lines on the soundstage, Digital Domain captured his Instead, as Pitt read the lines on the soundstage, Digital Domain captured his Instead, as Pitt read the lines on the soundstage, Digital Domain captured his January 2009 Hair He Is When Benjamin Button is fi rst born and very old, he has little hair, but even that sparse hair needed to be modeled, moved dynami- cally, and rendered. Mat- tais Bergborn led the team at Digital Domain that created a new hair system based on Maya's NURBS curves. With the maquettes for reference, the team paid particular attention to creating various ways of using the guide hairs to clump the hair. "Even his hair at the scraggliest has clumping behaviors and friction and electromagnetic effects," Bergborn says. "It might look good modeled, but it gets fuzzy and indis- tinct when rendered. So we had to give it structure and fi nd ways to make the light rays take more interesting paths to create shadows and highlights." The hair stylists could set global parameters, control areas with texture maps, and create clumps with guide hairs that attracted other hair; a virtual brush gave the stylists control over CVs within a radius as a stylist stroked it along the guide hair curves. Bergborn worked on Benjamin Button's hair for a year. "David [Fincher] was meticulous," Bergborn says. "He'd want minute changes. We had to create the hair on a shot-by-shot basis." –Barbara Robertson

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