Computer Graphics World

Motion Capture n n n n As the robots moved, pistons and gears in- side pumped and turned automatically via ex- pressions built into the Maya rig, and jiggle de- formers tied to the animation curves caused the heavy plating to react slightly, adding a subtle secondary motion. "If the robot turned to the left, an inner gear would turn clockwise at the same ratio," Nash says. "It gave the impression that the internal movement was driving the ro- bot, when, in fact, it was the opposite. The mo- tion capture was driving what happened inside; the internal mechanics were derived procedur- ally from the motion capture." The amount of visible damage increased as Each time a robot landed a punch on another robot, Digital Domain needed to change the model. Sometimes, the artists applied a new texture or displacement map. Other times, they deformed the model. A database system tracked the damage. Giant extrapolated motion data from the images captured by the witness cameras, ap- plied it to character meshes that moved against the background, and handed the result to Dig- ital Domain. Both studios, Giant and Digital Domain, tracked the camera. At Digital Do- main, artists removed the actors on stilts from the plates, re-created the backgrounds, and refined the performances. As for the boxing robots, after filming, Levy once again evaluated their performances, this time in the context of the live-action shoot. Giant then implemented any performance changes before sending Digital Domain the clean motion-captured data. "We also cleaned up the Simulcam," Madden says. "The Simul- cam gave us a decent level of camera track- ing, so once we got the approved shots from production, we sent a clean track to Digital Domain. They could put robots into the plate using those camera tracks and get quick temps not long after the live action wrapped." Postproduction At Digital Domain, in addition to the Simul- cam track, artists received plates with the cor- responding motion-captured data from Giant that matched the frame range in the plates. "Giant would give us the [Autodesk] Maya scene with a camera, a proxy plate, and the motion-captured data on our original skel- etons with the proxy geometry," Gillberg says. "We had the camera track from the Simulcam, the plate from the motion-picture camera, and the motion capture from the virtual camera. So first, we'd render the Giant scene to double check. Then we'd ingest that data onto our high-resolution robot rigs and test that. And afterward, we'd send the shots through our pipeline and lighting packages, with default lighting using [The Chaos Group's] V-Ray. That gave us temps right away. We didn't have to wait for a tracking team, or for animators to bring in the motion capture. So it was a great head start. We'd know what worked." There was cleanup, of course, of the camera track, capture data, and animation. But, the temps let the artists see how the robots looked in the various environments. "Giant got us 80 to 90 percent there," Nash says. "It was the foundation. It was the heaviest use of motion capture I've been involved with. And, we did a lot of work on top, especially for the robot contact. There was no shot with straight motion capture. We made the robots' punches appear harder. We did keyframe ani- mation for nuance and subtlety, to finesse and fine-tune the performances. And, we spent a lot of time in R&D on robot damage." No Bull Oddly, one of the biggest challenges for the crew at Digital Domain was a bull, not a robot, and chances are many people won't realize the bull is a CG creature. "They shot most of the plates with a real bull running around, but they couldn't punch a real bull," says Paul George Palop, CG supervisor. "So we had to add a CG bull for key moments, and that single asset was more complex than we expected. We had to deal with fur, muscle simulation, skin simulation, and photo- realistic rendering of organic skin. It required a lot of work for the animators also, because there's heavy interaction between the bull and a robot. And, they're both kicking an incredible amount of dust and dirt, so some of those shots are quite complex. The bull is in only approximately 15 shots, but those were some of the toughest shots in the film." –Barbara Robertson October/November 2011 23 postproduction progressed, with two of the robots suffering severe damage. To bang-up and batter the robots, the artists at Digital Do- main needed to create new surfaces and tex- tures, and sometimes change the models. Each time a punch landed, metal had to deform or the surface had to change. "Tracking the dam- age was quite a logistical challenge," Nash says. "We had to be very precise about what level was appropriate for each shot so that damage didn't suddenly disappear." Damage Control The Crash Palace sequence had the most grue- some fight—one between Noisy Boy and Midas—but the hard-metal boxers damaged each other throughout the film. The artists had to add hoses that dripped fluids, sparks, and smoke. "We had to choreograph a se- quence of events for where the punches landed and what the effect was," Palop says. "Creating the damage involved several departments—we were doing everything: texture maps, displace- ment maps, modeling. We had to crush, bend, deform, and break pieces of the robots. So, we developed a system that knew what damage level to apply to which shot. We had a database with all the information regarding damage for

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