Issue link: https://digital.copcomm.com/i/27779
CGI n n n n Triage To cope with the number of characters in the film, ILM used a bit less geometry and a lot more displacement. “A lot of our characters had low CVs, so we had to optimize for displacement,” says Tim Alexander, visual effects supervisor. And that produced interesting rendering challenges. “We’d get displacement pops,” Alexander says. “Hair sizzle. Other problems. So, we assigned two CG supervisors—Pat Myers and Kevin Sprou—to render triage. We told the TDs that if they spent more than an hour on a problem to call their supervisor or send the problem to render triage.” For Myers, that meant spending much of the show fixing problems. “We had a lot of shots in play, and artifacts would show up in a render, so we worked on the noodly problems with the complicated solutions.” Light leakage, for example. “One time we ended up with infinite numbers inside part of a calculation, which produced cool effects,” Myers says. “It made a character look like it had explosions of light under the skin. Or, we’d run a scatter calculation and suddenly have random spots with bursts of red glow on a character’s teeth. We called them the red dots of death.” That turned out to be a slight bug in Pixar’s RenderMan that showed up with a specific kind of geometry and specific kind of lighting environment—which the RenderMan team fixed. The triage team fixed a tiny buzz that showed up on the edge of a sheriff’s badge in an extreme close-up. A sizzle in the specular highlights on refracted glass. And, sometimes, they gave up. “We’d do as much as we could and then the ‘p’ word came up,” Myers says. “We’d say, ‘Well, we can paint.’ I was amazed we held off from doing that more; we really didn’t want to go down that path.” Myers also kept an eye out for renders that ran too long. “I didn’t keep track of stats, but I can guarantee that some frames rendered for pretty close to a day. Sometimes that was in error,” he says. “When people are chasing artifacts in a problem shot, they turn up the quality knobs, and then after they fix the problem, they tend to leave the knobs turned up. I told everyone that if they had a shot that ran for 24 hours and didn’t finish, to call me.” When Myers first started on the film, he worked on creating a terrain shader to help the artists deal procedurally with the details in the huge desert environ- ment. But then, he moved into problem solving and stayed there. “With most problems, if you attack them from a bunch of different angles, you can get to the bottom of them,” he says. “I’ve always enjoyed problem solving. But I felt a little like the elves working on the shoes.” –Barbara Robertson the Beans he had in mind, the artists asked the animators to help them create a motion test. “We had her point a shotgun at the camera and do some dialog,” Steele says. “Only then did the director see that we had come up with the character.” Te first two characters the look-dev team worked on were Rango and Priscilla (Abigail Breslin), a cute little girl based on a Madagascar rat who has an unusual fondness for death. “We started with the sweetest characters,” Steele says, “which was good, because we hadn’t perfected techniques for dirtying things up.” In fact, when they first started dirtying up the grungy characters, it didn’t feel right. “It was too disturbing,” Steele says. “So, we pushed ahead slowly. CG makes things clean; there’s a real art in making things dirty. One person added matted hair. Te next added dirt. And then late in preproduction we started look dev on the inbred rodents. Mike Halsted had gotten quite far with the level of distress by then, and they were just disgust- ing. Matted, hairy, everything they should have been.” Once the characters passed their turntable examination, they moved into production, but the look-dev artists kept a close eye on their treasures, all the way through to the end. “Each one is like a little Faberge egg,” Steele says, “little jewels that everyone contributed to. It’s our job to maintain them.” Te TDs were, in a way, customer support technicians for the characters. Tis meant during production, for exam- ple, when Verbinski noticed that the eye lines in the rendered shots weren’t the same as in the animation he had finaled, it was up to the look-dev TDs to fix the problem. “In this case, we realized that refraction caused an error that was measurable,” Steele says. “So, we fixed the problem, and the shot TDs imported the fix into the shots.” Te problem arose because the anima- tors didn’t see the refraction, and refraction can skew the eye line. So, Jason Smith, a TD supervisor, configured Maya to give animators a preview of what refraction would do. “Tere was a deeper problem, though,” Steele says. “It wasn’t just eye direction. Our eyes have an ap- parent depth to them, and where the eye was sitting in the socket caused part of the prob- lem. Tere were lots of little issues like that, so we were always on a heightened state of alarm. It was quite nice when the show ended and I no longer had to worry about being respon- sible for things that could blow up.” Keep Them Doggies Movin’ James Tooley led the team of creature-de- velopment TDs responsible for rigging and skinning the characters, and for dynamic simulations. Most of the characters were bipeds that could use an evolution of rigs developed over the years at ILM. Te main innovation for this film was that the riggers created a GUI for each character—a request from the animators. “Animators could manipulate the charac- ters in Maya, or select parts of the character through the UI without touching the screen in Maya,” says Brian Paik, associate creature supervisor. “Te two systems would update each other.” Te riggers also added a little squash and stretch to the rigs to give the characters more flexibility than a character in a live-action film might require, and gave the animators the ability to tweak the characters’ silhouettes us- ing extra deformers on the skin. In addition to the bipedal characters, the rig- gers set up systems for quadrupeds, characters with wings, and one massive snake. “We had everything,” Tooley says. “Feathers, scales, hair, multiple layers of clothing that we dynamically simulated.” For characters with wings, the team created one rig that worked whether the bird folded its wing or flew. In the past, animators had to work with separate rigs. Te snake was even trickier. If stretched out, Rattlesnake Jake (Bill Nighy) would be 100 March 2011 15