Computer Graphics World

November/December 2014

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n o v e m b e r . d e c e m b e r 2 0 1 4 c g w 3 3 glass, steel, volume rendering, and atmospherics with no lim- its. We could have done this film without Hyperion. But, it would have been a different film." O T H E R T E C H N I C A L A C H I E V E M E N T S Hyperion, though, as remark- able as it is, wasn't the only technical advancement realized for the film. "This was our most ambitious film ever," Driskill says, and lists several reasons why. "We built a geographically accurate version of San Fran- cisco with every lot and building height," he says. "We worked on aspects of it for over a year, going back and forth with visual development in terms of com- plexity. We built it procedurally using template environments for districts. Our biggest shot had 350,000 unique elements." To populate the city, the crew designed a new system called Denizen that put 6,000 people in the opening shot, and created an animation retargeting system to work with Denizen. "CG films have oen felt like they were filmed on a soundstage," Driskill says. "Fiy feet out you have a painted backdrop, and you have the same six crowd characters. We kept pushing further and further because we felt unlimited." The team also built a new system called Parade to help animators. When an animator manipulates rigging controls, Parade calculates the effect of those changes on neighboring frames, which helps animators iterate more. Some of the new tools cen- tered on Hyperion. For example, they refined and improved a frame interpolation technique that sister company Industrial Light & Magic had built for Pacific Rim. "If we ended up without enough bandwidth to render every frame, we could have rendered every other frame and interpolated," Driskill says. "By the time we were in shot pro- duction, we didn't need it, but we now have a cool frame-aver- aging technology. We can break out layers and average them, and it does nice noise reduction as a side effect. Hyperion, like any path tracer, is nonlinear in the time it takes to squash the last bits of noise. This helps clean up those last bits of noise in the image, so we can chop off one turn of the crank." To further reduce rendering time for some shots, the team created Façade. "Global illumination is inter- esting because you bounce light in the whole world to create im- agery," Driskill says. "But, when we're in Hiro's bedroom with the sun coming through the window as the light source, Hyperion spent most of the time render- ing San Francisco Bay out the window. It had loaded the entire city. Even though Hyperion allows an obscene amount of geometry in a scene, we didn't need that. Facade pre-bakes the illumination outside, then builds a piece of geometry outside the window with that pre-baked illumination." The effects team also had technical challenges – espe- cially in creating Hiro's little mi- crobots, which use magnetism to connect to one another and disconnect. Other challenges were in creating effects partic- ular to each character, and in producing a signature effect for the climax, which involves an environment created entirely with volumes. But of all the accomplish- ments, the breakthrough idea for rendering encapsulated in Hyperion stands out. It's tempt- ing to call the Hyperion team the Big Heroes on this film. "Hyperion was absolutely a crazy idea," Driskill says. "When Brent brought the idea out, we went, 'Oh, wow. It's revolution- ary.' We went to Ed Catmull, and he said, 'Go for it.' " And they did. The rest is CG history. "I've watched the San Fransokyo flyover probably 100 times," Driskill says, "and I'm still excited about it." ¢ BIG HERO: BIG RENDERFARM To render Big Hero 6, Disney used a large renderfarm run by a program called Coda. "When I say large renderfarm, I mean world-class," says CTO Andy Hendrickson. "We had 55,000 cores in four different places in Los Angeles and San Francisco running 400,000 visualization jobs per night." Even so, Big Hero 6's render hours topped those of previous shows by far. Tangled had an overall render footprint of 11,500,000 hours. Wreck-It-Ralph needed 21,900,000. Frozen's ice and snowy landscape upped that to 62,800,000 hours. Total for those three: 96,200,000. Double that and add another seven million render hours and you have the total for Big Hero 6 alone: 199,000,000 render hours. –BR Barbara Robertson is an award-winning writer and a contributing editor for CGW. She can be reached at BAYMAX AND HIRO SOAR OVER A BEAUTIFULLY RENDERED, HIGHLY DETAILED SAN FRANSOKYO.

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