Computer Graphics World

n n n n Motion Capture that the artists at Digital Domain referenced, and the client provided concept art for the other robots. "We photographed the robots at Legacy for modeling and texture reference, in stages," says Paul George Palop, CG supervisor. "We didn't want to wait for them to finish before we began. With the concept art, we had to grab the main idea of the robot without changing the look and make all the mechanics func- tion. That took a lot of back and forth from the art director, director, and modeling depart- ment. Sometimes concept art looks good on paper, but the models can't move." For the motion-capture sessions, the crew At top, Digital Domain used a clever new 2D card-based system to populate the stands in the arena with multiple copies of live-action extras. At bottom, artists at Digital Domain referenced models built at Legacy FX for textures, and designed more than 30 materials for the robots' surfaces. motion-capture sessions that would take place at Giant Studios—sessions the team called "performance capture" and "camera capture." The goal was to give Levy, first, the ability to direct stunt actors on the motion-capture stage at Giant and see, in real time, the boxing CG robots; and second, the opportunity to frame shots of the robots fighting in environments matching the locations where he would film the live action. The capture sessions also pro- vided the in-ring fighting robots seen through the Simulcam system while the filming oc- curred on location, as well as the performance data for Digital Domain's final animation work later. "We called it 'pre-capture,' " says Matt Mad- den, vice president of Giant Studios and the studio's performance-capture supervisor. "We couldn't do the motion capture on location because the robots needed to be one and a half times larger than a human. If you do a straight map of data from a six-foot human onto a nine-foot robot, it doesn't look right, so we couldn't have the robot actors in the same ring as a [human] actor. We had to put the robots in smaller rings." 20 October/November 2011 There was a second reason for creating the fights early, one perhaps equally important. "Shawn [Levy] wanted to educate the actors about the intent of the fights. He wanted to go on location with a solid understanding of what each fight was about," Madden says. "Not a typical previs. He wanted a scene cut with the editor based on the actual performance of the robots. This turned out to be tremendously valuable during the shoot." Setting the Stage Prior to the capture sessions, Digital Do- main created environments and CG robots that would work with the Autodesk Motion- Builder-based pipeline used at Giant. Robot modeling and rigging for the eight main ro- bots began in December 2009. Environment capture took place in February 2010. "We had a two-pronged task for the robots," Nash says. "One was to start the full develop- ment on the high-res robots, but also quickly create lower-resolution versions that Motion- Builder could handle." Legacy Effects had be- gun work on practical models for three of the robots —Ambush, Atom, and Noisy Boy— created low-res models of the robots fitted with simple rigs. "We only used the low-proxy models for the motion-capture sessions and playblasts," Palop says. "The final models were a hundred times more complex, with moving parts." Although each robot had its own look and personality, none of the robots talked. There was no facial capture, and no need for modelers and riggers to add elaborate facial systems later. While the modelers worked at the studio, a separate crew from Digital Domain traveled to Detroit where filming would take place, to scout the physical locations and do photo surveys. "We wanted to create a fairly accurate but not labor-intensive virtual environment for each of the fights," Nash says. They then gave the geometric framework for each loca- tion they surveyed to Giant. Performance Capture At Giant, the stunt actors worked in rings that were roughly 75 percent of the actual ring sizes, which varied from 18 feet to more than 25 feet. Giant turned the rings into cap- ture volumes by surrounding them with an 80-camera optical system. Outside the ring, stand-ins played the roles of Charlie (Jack- man), his son Max (Dakota Goyo), and a few crowd extras, which would help Levy choose camera angles later. To adjust for the scaled- down ring, Giant placed the stand-ins on a lower level. "If Atom [the robot] had to look down, we got a close approximation of where he would need to look in the final shots," Madden explains. During the performance-capture sessions, Levy referenced storyboards, communicated what he wanted to the stunt coordinator and the fighters, and directed the fights as he would have directed actors on location. Although Gi- ant could have given him real-time robots to view during the fights, it didn't. "We've found that when we're capturing the performers, the

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