Issue link: https://digital.copcomm.com/i/491590
m a r c h . a p r i l 2 0 1 5 c g w 2 3 performance," Harvey says, "and embellish it. They also added Sharlto's performance to the stunt actors." The filmmakers shot the entire movie on location; there were no digital environments or digital extensions. However, to integrate Chappie into those environments, the crew created digital versions of all the loca- tions. In all, the crew created between 65 and 70 environ- ments with unique light rigs. "We didn't Lidar-scan the locations," Harvey says. "We took hundreds of thousands of photos, used [Agiso] PhotoScan to create the digital versions with photogrammetry, built models based on that, and then mapped the low-res geometry with HDRI photos. We didn't take only one area, we took a series along an entire path to map out the entire vol- ume. Then, we'd reproject onto this low-res digital environment, to reflect light back onto the digital character. That way, you could see the reflection move as he walked past a table, for instance. It gave a real dimen- sionality to the lighting." For compositing, Image En- gine uses The Foundry's Nuke; for rendering, DNA Research's 3Delight. For lighting, the studio uses its proprietary soware called Gaffer. A R T I C U L A T I O N On set, the filmmakers would pose and position the practical robots, so those 3D-printed props needed to articulate cor- rectly. But for the digital robots, the animators needed a more complicated articulation. "The shoulder and hip joints were the most difficult," Poon says. "The robots needed to put their hands over their heads and across their chests." Although a CG robot's joints could, theoretically, move with more degrees of freedom than a human's, the crew restrict- ed the movement to what a human could do. But, that didn't make the joints easier to design, model, and rig. "Chappie has an incredibly complicated articulation," Har- vey says. "He isn't a toy robot. He had to be a strong police robot, so every joint had to be a single axis for strength. For side- to-side movement, we have a separate joint." There are no ball joints in the robots. The shoulder joint com- prises three joints; the knee, two. Bending metal wasn't an option. At Image Engine, a new IK solver managed the complex articulation, but the rigging process continued throughout the animation process. Three riggers worked on Chappie, one at a time through the project, with help from R&D to develop new ways to move the metal parts. "The animators saw pretty much the same system as always," Harvey says, "but the system underneath is technical- ly complicated." The big question was Chappie's facial expressions. Animators accomplished facial expressions within a limited set of possibilities: an eyebrow bar, chin bar, ears, lights, and icons for eyes. "On any visual film, the goal is to make the character believ- able," Harvey says. "We had made Chappie plausible, but had to go beyond to have people believe him as if he were a person. We had to create emotional arcs." E M O T I O N Aer shooting on the film end- ed in January, the Image Engine crew did postvis on the 1,000 shots with Chappie. TOP, MOOSE WATCHES CHAPPIE LEAP FROM A TALL BUILDING. BOTTOM, CHAPPIE'S MECHANICAL SHOULDER HAD THREE SINGLE-AXIS JOINTS RATHER THAN A BALL JOINT. " THE ROBOTS NEEDED TO PUT THEIR HANDS OVER THEIR HEADS AND ACROSS THEIR CHESTS."