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June 2010

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COVER STORY Eclipse’s furry woodland creatures B By KEN McGORRY mcgorry@optonline.net Tippett Studio conquers millions of strands of clumpy fur for Twilight:Eclipse’s CG wolves. ERKELEY, CA — For New Moon, the second installment of the Twi- light vampire series, director Chris Weitz tapped Phil Tippett’s studio to help in- troduce five menacing new characters — wolfmen (and woman) who shape shift from humans to realistic wolves. Tippett and company (www.tippett.com), including art director Nate Fredenburg, threw themselves into their lupine studies with characteristic intensity.The shop is well known for its early stop-motion work and its mastery of solid-body CG creatures such as the giant warrior insects seen in both Starship Trooper films. But wolves are different. And they got different again for the latest Twilight film, Eclipse, directed by David Slade. For this third installment, Slade wanted more CG wolves (from five to eight), bigger wolves, and more physical interaction between the actors and the wolves.This includes every- thing from affectionate petting to fur pulling, fighting and biting, and a big wolf vs. vampire battle sequence. Visual effects supervisor Eric Leven con- siders himself a long-term member of the Tippett VFX family — he spent two months on location in Canada with the company’s namesake and the Eclipse pro- duction crew. But he was new to CG wolves. Prior to delving onto the third movie the Tippett artists who worked on New Moon familiarized Leven (who shared VFX supervision with Matt Jacobs) with their CG wolf characters. Slade also wanted a different look for his wolves. “We had to change some of the ‘groom style,’ the amount of fur, some of the colors of the wolves,” Leven says, “minimal changes but enough to make it interesting.” In the beginning the production asked Tippett Studio’s Eric Leven: Getting a variety of CG looks “really, really fast.” Leven and company to render more and more CG fur on the creatures. Fur is difficult and the Tippett staff needed to rethink their tools, workflow and memory management. However,“what they were really looking for was a different type of fur sheen,” Leven says. “You can have fur that looks soft or looks coarse and it doesn’t necessarily have to do with the amount of fur.”The Eclipse production team wanted their wolves’ coats to suggest a “softer, less clumpy feeling.” Ulti- mately Leven and company did increase the amount of fur significantly “but we also changed the style of the groom.” 10 Post • June 2010 INTERPOLATING FUR To increase the volume and malleability of the fur,Tippett started with a set of “guide hairs” on a model’s surface which would serve to direct the action of the CG coat. Guide hairs determine the fur’s position on the model’s surface, and its “clumpiness” as well as many other characteristics.“We cre- ate them in two different ways to save memory.” Paint maps also describe the fur’s GPU, allowing them to review a shot and get feedback much faster, although without all the nuances of lighting and shading. Leven says Eclipse features “a lot of long shots with eight wolves hanging out for six, seven, eight seconds at a time. It’s safe to say that if we had not come up with [the node- based] technique, we would not have been able to render the show.” In some se- quences, like when they’re observing a foe, The studio found new ways to “grow fur” for different looks than those used in New Moon. The bottom left is an occlusion render of Tippett’s fur groom, and the right shows muscle sculpting. length, coarseness, width, color and more. Eclipse’s CG wolves sport a secondary layer of fur that, to save memory, does not follow the guide hairs; instead they are pure inter- polation. “It was a new technique for us,” Leven says.“It allowed us to grow a lot more fur and get a really different look than we were able to get on the last show. Render- Man is optimized to grow millions of hairs, but you still have the limitations of the amount of memory you can deal with.” The new fur system is more node-based than paint-map-based.“It actually works like a compositing package,” Leven says.“You can get a variety of looks really, really fast.”Tippett’s compositing supervisor was David Schnee. The node-based system allowed the team to use “hardware preview” via the www.postmagazine.com the wolves hold still. In such static shots the fur’s verisimilitude is of great importance be- cause the audience can focus on it. Tippett used Maya for animation, Shake for compositing, as well as Nuke, and its custom- built fur system was newly overhauled. CG su- pervisor on Eclipse was Aharon Bourland and CG character supervisor was Stephen Unter- franz.VFX producer was Ken Kokka. INTERACTION There are dramatic fight sequences in Eclipse and here again the Tippett interpola- tion technique helped the team add realism with virtual snow. Tippett Studio had to come up with continued on page 39 VFX

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