Computer Graphics World

September 2009 17 CG I•Stereo n n n n to the parts library and did the initial set dressing for the layout teams. "We built detailed interiors for places the characters would go into and out of, and low-res interiors when you could only see inside the windows," Kim says. To sim- plify the modeling task, the team altered and replicated base models whenever pos- sible. A hallway made from thousands of egg cartons, for example, started with two models that the crew bent and placed in various ways. e largest interior set was Flint's labora- tory, and the biggest geometric part of that lab was a wall with 62,233 buttons. "We tiled sections and copied them, but we modeled each button that someone would push during the movie, so the amount of geometry on that wall was amazing," Kim says. "And, all the buttons had to work." For modeling, rigging, and animation, Imageworks uses Autodesk's Maya en- hanced with custom tools; for cloth simu- lation, an in-house solver called Tango. Tami, a custom renderer, works with hair groomed in Maya. Swami manages mo- tion cycles and paths for crowds. Painters and texture mappers work with Adobe's Photoshop and Maxon's BodyPaint 3D. Technical directors create the primary ef- fects tools within Houdini. For some ef- fects, they use a custom 3D sprite renderer called Splat, and for others, SVEA, a volu- metric renderer. Imageworks' Katana han- dles 3D lighting and 2D compositing. And Imageworks' in-house version of Arnold, raytracing software developed originally by Marcos Fajardo, now a software architect at Imageworks, rendered the film. Crazy Colors "Our bible for the movie was the artwork the production designers gave us, and we adhered closely to the artwork, from light- ing, to design, to the stylization of the food," says Bredow, "so much so that when we compared our shots to the artwork, as we wiped over the art, you could hardly tell where the transition was." All well and good, except that stylized food doesn't always look delicious enough to eat. It was up to the look dev team artists, four CG supervisors, and a team of TDs to make the 50 different edibles believable enough to be appetizing yet fit within the film's brightly colored style. "We were excited that the directors wanted a stylized look in terms of charac- ters and shapes in the environment," says Danny Dimian, CG supervisor, who laid the groundwork for the Arnold shader writ- ers. "We had two shader writers and a lot of support from the Arnold programming team," he says. "For our show, they wrote the shaders in C++, so it wasn't as simpli- fied as it will be later with the open-source language Larry Gritz is working on." Early in the film, when the people in the town were poor and down on their luck, the lighting team created a muted environ- ment using only a few colors. When the food began to fall, the colors intensified. "We had purple skies and incredible or- ange skies," Dimian says. "At one point, we heard that we weren't pushing the colors and the look far enough and that we all needed to go to 'crazy school.' So we took that comment to heart. When the charac- ters go inside the meatball, we went as far into the color space as we could to get lots of crazy hues. But, the lighting needed to behave realistically, partially because the movie would be in stereo 3D." e team believes that the global illumi- nation built into Arnold made it easier to achieve the realistic lighting they wanted. "In Arnold, we'd set up a sun and a sky dome, and we'd get a really beautiful look right out of the box," says Daniel Kramer, digital effects supervisor. Because lighting with Arnold closely re- sembles lighting with real-world lights and because many of the lighters had worked only with scan-line renderers, Bredow sent them to classes at Mole-Richardson, a well-known Hollywood lighting company. "With Arnold, the size of a light dictates its shape, the size of the shadows, and how soft or hard the shadows are, which is much more like lighting on set with live- action photography," Bredow says. "So, at Mole-Richardson, we had DPs walk our guys through live-action photography." e DPs lit sets mocked-up from art- work of a bedroom, complete with a bed, tables, sheets, and a window, noting how lighting they would use for characters walking through the set would differ from that in the artwork. "It was refreshing for me to have con- versations with the lighters about where to place bounce cards," Bredow says. "Because Arnold is a raytracer, it renders the shadows right in every shot, whereas on previous Modelers built four versions of the town Chewandswallow. The mad scientist Flint and his sidekick Steve survey the damage in a detailed model of a building destroyed by the falling food.

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