Issue link: https://digital.copcomm.com/i/30784
n n n n CGI man’s RBD (rigid-body dynamics).” In addition, an IK-based rigging system gave animators the ability to pose the chain. “But we needed a third method that was a blend between the two systems,” Stichweh says. “And the blend needed to look natu- ral.” The goal was to give animators the abil- ity to attach two shackles, run a simulation in which the chain would act normally, and then transfer that motion to a keyframed ribbon. “When we achieved that, we bridged the two 50,000 people watch a parade with thousands of costumed dancers riding on floats and per- forming between—represented a huge techni- cal achievement for the crew, as did Linda and Tulio, the human stars of the film. “We did a little bit of work on humans for the first Ice Age,” says Saldanha, “the baby and the fam- ily. But they were crude in terms of elements. They couldn’t talk. And we didn’t do cloth simulation. In this film, the humans play out a parallel story with acting performances and mators—they had to limit themselves. “We build a lot of functionality into our rigs,” Leach says. “The animators can pretty much sculpt the characters on a shot-by-shot basis; they can use our controls to sculpt the rig based on the camera angle. And, on top of that, the animators can add in shot deformers. They can push the rig far beyond what it is sup- posed to do.” Creating the humans’ skin also pushed the crew into new research areas. Blue Sky is jus- tifiably proud of its proprietary programming language and renderer, CGI Studio (also called “Studio”), a raytracer designed to simulate light accurately. Studio produces motion blur, reflection, refraction, global illumination, dif- fuse reflection, and depth of field using prin- ciples of physics. Furthermore, rather than creating complex and detailed surfaces with texture maps, artists at Blue Sky develop most materials procedurally. Mathematical Materials “We’ll use texture maps for graphics on signs, license plates, things like that,” says materials supervisor Brian Hill. “But we generated 98 percent of what you see on the screen proce- durally. It’s a different way of approaching sur- faces that we started with Robots (see “Mech Believe,” March 2005), and have kept going that way since. We like it. Because it’s math- ematically driven, it’s resolution-indepen- dent—if you procedurally generate a gradient between two points for a bump signal and zoom into it, it’s still gradating from zero to one between two points.” However, because the crew had yet to cre- At top, modelers and riggers spent two months revamping the bulldog Luiz to make him more appeal- ing when he moved into a starring role. At bottom, one rig managed the wings—whether folded, flying, or, as in this case, amplifying a performance. worlds,” Stichweh says. “Animators could grab a section of the chain that is a hand-animated joint. We had ramps and blends from that point on to transition linearly or with a spline into a simulation. It was almost like picking a necklace off the ground.” In other words, the tools allowed a simula- tion to pass through a set of key poses. “I knew it would be great,” says CG supervisor Rob Cavaleri, “when in a test shot the animators had Blu and Jewel jump over a car, and in the middle of the jump, the chain formed a heart and then relaxed and was smooth.” The Human Touch The Carnival—during which a crowd of 14 April 2011 cloth simulation, which was technically chal- lenging for us. So, we definitely built more controls to give the animators freedom to create subtle eye movements and facial expressions.” The riggers started with model sheets drawn by Pablos that showed various facial expres- sions, creating blendshapes that made it pos- sible for animators to match those expressions, and then they designed the rig to allow more. For animators used to pushing facial ex- pressions on the previous cartoony films, that freedom was an issue at first—cartoony ex- pressions on humans can look grotesque. “We had a lot of back and forth with animation to discover what made the most appealing faces,” Burr says. But, the riggers didn’t limit the ani- ate procedural skin shaders for humans, they turned to Carl Ludwig’s R&D department for help. Ludwig, now vice president and CTO at Blue Sky, co-founded the studio in 1987 with a group of people who had worked on TRON at MAGI/Synthavision. He and physicist Eu- gene Troubetzkoy developed the proprietary software and renderer. “To create the skin shader, Carl [Ludwig] used the same transmittance code base we had been using to give leaves and foliage a translu- cent look,” Hill says. “It’s kind of the equivalent of what other studios call subsurface scattering or translucency. Carl rewrote the software, plussed it up, and handed this new amazing feature to us. One of our senior materials tech- nical directors set up the core skin we used on every single human in the movie.” The transmittance produced the subsur- face glow for the skin. To create the surface, materials artists used procedural tools, dialing parameters that added pores, shininess, and so