Computer Graphics World

March/April 2013

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n n n n CG Characters (Top) Actor John Kassir, who played General Fallon's little head, stood next to Bill Nighy, who performed the General Fallon giant, during motion capture. (Bottom) Giant Studios handled body capture on set while, at the same time, Digital Domain managed the facial capture. a virtual camera session. This was rushed, so we did them together." The virtual camera was a tablet with characteristics that mimicked the cameras that the production crew would use later on set. "Bryan and Tom Sigel [Newton Thomas Sigel], the DP could compose shots while the actors per, formed on the motion-capture stage," Rosenbaum says. "At any time, we could capture up to 10 or 12 actors, depending on the action." The captured motion from the actors and the virtual camera went to Digital Domain and to The Third Floor. At The Third Floor, previs artists refined the camera and tightened the edit in preparation for principal photography. During filming, the CG giants appeared in camera as if they were on location. On Set This virtual production technique proved especially important for a sequence during which Fallon drags a mace (a ball on a chain) through the Norwich Cathedral. A camera on a crane follows the mace and then booms 24 feet up Fallon's body and settles on his face as he turns into the camera for a close-up. "We wouldn't have been able to create this shot without SimulCam," Rosenbaum says. 26 "The odds of guessing where the CG character was in that space would be slim." Prior to filming in the cathedral, a Digital Domain crew had surveyed the location to produce an accurate previs environment. During the pre-cap motion-capture session, Nighy and Kassir, who played two-headed Fallon, had performed in that replicated environment, and data captured from them had been transferred onto the CG giant. The CG character then moved into the Simul am system for filming. "Giant Studios C put motion-capture markers on the live-action camera and composited the virtual character into the environment being filmed in real time," Rosenbaum explains. Thus, the DP and camera operator could look through the eyepiece and see Fallon in the cathedral. "Our character was just like an actor," Gilberg says. "A 24-foot actor. The camera operator could look at him or not; the giant stayed in his own world space." The crews used the same type of system for sequences filmed outdoors. "They filmed the show in stereo using 3ality's Epic rigs," Gilberg says. "The stereo rig is so heavy it always ends up being on a crane, which means there isn't as much freedom moving the camera. That one drawback, especially for virtual production, is also a plus. On the plus side, we had Giant Studios encode the crane, which we hadn't done before. On Real Steel, we had active markers and a motion-capture volume for the cameras." Even without the hindrance of heavy cameras, the crew might have used the crane anyway. "It was too windy to put up a truss for motion-capture cameras," Gilberg says. "So, we used old-school encoding with realtime playback through [Autodesk's] Motion Builder. The plus was that we ended up with a much smaller footprint than if we would have used a truss and 30 or 40 cameras." CG Giants The audience first sees a giant during a chase sequence. The character Crawe (actor Eddie Marsan) has climbed the beanstalk to the land of the giants and discovered Fee. "Crawe hides behind a tree," Rosenbaum says. "Fee comes up behind him and rips the tree out of Fallon Under Water During one sequence in the film, the two-headed giant Fallon swims under water, through a moat. "With specialized motion like this, the question is, Do you keyframe it or what do you do?" says Digital Domain Visual Effects Supervisor Stephen Rosenbaum. "The shot continued from where Bill Nighy and John Kassir were acting on the motion-capture stage, so both actors were there. You could hook keyframe to the subtle [captured] acting. But, we developed a technique in Avatar that I exploited here. I took the back off a rolling office chair, had Bill Nighy lie across it, and I pulled it across the motioncapture volume while he mimed the action. It looked silly and it raised a lot of eyebrows. But it works. It gave us his distinct motion, and we didn't have to keyframe that later." – Barbara Robertson March/April 2013 CGW0313-Jackpfin.indd 26 3/14/13 12:15 PM

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