Issue link: https://digital.copcomm.com/i/3597
October 2009 44 n n n n Visual Effects which they built CG helicopters and planes, and added dust trails and explo- sions. "I was on set at a quarry south of Woburn, Massachusetts, for this," Nugent says. "It's supposed to represent an Afghan- istan-like warscape. ey had folks dressed in surrogate army gear and pyrotechnics going on. We did sky replacement, set ex- tensions, and a lot of battle-scene enhance- ments—explosions, firebombs, blasts, gun hits, missile trails—all that fun, active stuff." For the 3D work, the artists used Maya, and for 2D, Shake. Sandbox also did R&D and look de- velopment on the "overload device," also known as the OD, which kills surrogates. "We did that in tandem with MPC," Nugent says. "Mark had both of us ping- ponging, simultaneously zeroing in on a look. In the film, when someone aims the OD like a blow-dryer at a surrogate and presses the trigger, it sends an energy field toward the surrogate." e Sandbox artists created the effect using a combination of 3D and 2D. e 3D artists created gray-shaded mattes that controlled particle animation, and then the 2D artists used filters to warp and dis- tort the background and to add colors and other effects. "We also had Assemble help us with a shot in which the camera flies into an eyeball as it's blasted by the OD device," Nugent says. "ey did the basic CG, and we did the compositing and 2D en- hancement." MPC Vancouver: OD Device, Arm Stump, Dead Surrogates MPC Vancouver used a similar method to create the OD's energy field. e art- ists generated particle streams in Maya that they moved into Shake for compositing, driving displacement with mattes, 2D ele- ment passes, and 3D elements. "We start in Maya and then have a number of pro- prietary systems to take Maya to the next level," says Doug Oddy, VFX supervisor. ey put those systems to work on a shot in which the OD device kills police officers. "We built digi-doubles to roto- animate their movements so we could launch the effects from the digi-doubles," Oddy says. "We have a subsurface lighting effect under their skin. eir eyes explode, and we see the machines coming apart. We did a lot of shader work, and on top of that, we had a tremendous amount of compositing and re-lighting." e bulk of MPC's work, though, cen- tered on replacing Bruce Willis's arm with a mechanical stump following a chase se- quence during which the arm of Greer's surrogate is severed at the bicep. Willis wore a bluescreen sock on his arm for the remaining shots starring his wounded sur- rogate, and MPC attached a CG burned, charred, mechanical stump with leaking fluids to his shoulder in the filmed plates. "e mechanical device mimics human kinetics, so we used the human body as a template and created a hydraulic-based sys- tem," Oddy explains. "We thought of each muscle as a series of bladders that can cause a muscle to extend." Because Willis starred in some shots and stunt doubles in others, MPC scanned both Willis and one double to create a hybrid Greer, and then roto-animated the mechanical stump into place. "It was fairly straightforward" Oddy says, "but roto-animating movements is always time-consuming. We used the same rig for the actor and the stuntman, and flexed it so we could reposition the subtle physical changes between the two." e fluids, however, required R&D. "We worked closely with Scanline to get the level of viscosity we needed from [its] Flowline software to have the fluids leak out of the arm the way we wanted. We wanted them sort of pulsing out, as if a pump is running," Oddy says. "So, we built a rig within the system to get consistent results for all the shots." In addition to the CG arm, MPC put the digi-double's whole body to work, as well. "By and large, Bruce [Willis] did the stunts, but Greer is kicked around pretty good," Oddy says. "Our digi-double is a hybrid Greer that can leap across 60 con- tainers and get impaled." MPC also created a digital replica of a helicopter that the studio fitted with digi- doubles for Greer and a police officer, and, as did all the studios, smoothed actors into surrogates with a little airbrushing. "SSI [Synthespians] did the heavy lifting, but we did a little of this difficult work," Oddy says. "We could rotate our digital Greer around and pull a piece from it at the angle we needed and render it in the right lighting conditions for the composit- ing team." Because they had built Greer as the smooth surrogate, they could graft little pieces from that model into Willis's face, if needed, for his surrogate version. But, it wasn't easy. "Any time we seem to get a handle on our collective ability to do something," Oddy adds, "we up the ante. We can have VFX house Assemble built a computer-generated factory and manufactured the surrogate robots in the factory, as well.