Computer Graphics World

Simulation To create Glago's hair, beard, and mous- tache, the crew pioneered the use of Dis- ney's XGen software with geometrically sculpted hair. "Hiroki modeled every tuft so it could be art-directed," Hollings says. "He sculpted the tufts, and then Mitch Snarey grew the hair to fill the volumes. I think that's the first time we've constrained hair into volumes here." For Glago's coat, character effects su- pervisor Ian Coony traveled north to Pixar to talk with the crew that handled the clothing for Ratatouille. "John [Lasse- ter] was over the moon about how good those clothes looked," Hollings contends. "But, they were cotton. Glago's coat is wool." Ultimately, though, Coony used Disney's Fabric in-house cloth solver for the dynamics. "It was a fairly straightforward simula- tion process," Hollings says. "Once we fi- naled the animation, we'd run simulations, and once the simulations looked good, we'd bake them into files." e other major simulation task, con- trolling the little alien orbs, was less straightforward. Effects supervisor Cesar Velazquez created a process that started with particle simulations in Side Effects' Houdini to produce the general motion of particles moving from one point to an- other. en, using Houdini scripts, he cre- ated additional layers. With one, he added collision detection so the particles wouldn't interpenetrate. Another added deforma- tion so the little green balls would retain their volumes. "He gave us 'wedges' with 1000, 2000, 5000, and 10,000 orbs," Hollings says. "e more the orbs, the slower the simulation." Velazquez also offered Williams different choices for how the orbs moved—bouncy, slowly, treadmill-like motion, and so forth— and with the orbs moving as a group or with some orbs moving independently. Effects animator Dave Hutchins created most of the other particle simulations—in- cluding the blowing snow, interactive snow, and objects moving inside Glago's house— with Maya, using hardware rendering in some cases. He also added Glago's breath to every shot in which the star appeared. Road Testing Each night, when the render queue light- ened up, the system automatically created a simple render of all the shots. "e pipe- line was completely push-based," Hollings says. "As an animator finished, the lighter would get the new animation. If someone moved a chair in a room and I was working on the same shot, the next time I rendered it, the chair would have moved." e nightly auto-render served as a troubleshooting tool. "It rendered every- thing in a simplistic way, and also the cloth sims," Hollings says. "It was a way to see the status of the show every day and dis- cover anything that was broken." Pixar's Mike King helped the team de- velop the asset management tool, which they named Nani. "at was the tool that managed all the master sets, populated the shots with elements, and created Maya files," Hollings says. "We also took advan- tage of having people on the crew, who had come from many different studios, help create tools across the board. We put our heads together and thought about what we would do if we could create a pipeline any way we wanted." For example, iPlay, written by Sung, gave the artists the ability to look at the whole short and select what they wanted to see within a sequence. A navigation system that moved quickly within the file system made it possible for the artists working on something within a particular shot to play the shot easily. "We tried to create the most efficient pipeline possible in a small scale," Hollings adds. Some of the tools and techniques road- tested for "Glago's Guest" helped power Bolt. "We transitioned from using tile- based texturing to facet-based texturing, which Bolt then used," Hollings says. "And, some ideas are being considered by the Ra- punzel leadership. Even though exact tools may not move to other shows, the ideas flow when the people join other crews. But, that wasn't the point. e point was to explore and innovate. It isn't often that you get the opportunity to do a show any way you want, and to succeed or fail." Succeed, they did. Sometimes, the big- gest achievements happen way behind the scenes. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. A new lighting package called Lilo, developed for "Glago's Guest," helped the lighting artists produce the film's stylistic photoreal look quickly. n n n n CG Short Films February 2009 20

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