Issue link: https://digital.copcomm.com/i/225858
with Disney researchers in Zurich, Switzerland – "where it's easier to get snow, Kallianpur laughs. There, the team mea" sured the diffusion profile of snow with lasers. "We had weekly meetings with them and our shading department to talk about the technical aspects of rendering snow, Kallianpur says. "We ended up shaping shallow and " deep subsurface scattering lobes according to real data and then combining the two different effects. It isn't raytracing through a volume; it's an approximation. But, we got a nice lighting effect. " All the hero characters benefited from the R&D into subsurface scattering, as well. "We used a similar technique for their skin with shallow and deep subsurface scattering, but with different lobes than the snow, Kallianpur says. For the deep " snow and snow that the characters interact with, the lighting team used a completely different shading system that lit the snow as if it were a volume. Olaf, however, provided a unique challenge: He's a snowman in snow. "We used a cheat to make him stand out, Kallianpur " says. "We always made him pop by using value – he's a little brighter than the background behind him, or we placed a shadow behind him. Or, if he's in a saturated environment, he might be slightly more neutral. And, we always had rim light on him. " Throughout the film, the lighting artists took care to use hues and saturations that kept the film from looking too white, and at the same time, made sure the snow never turned gray. "Even in our bleak scenes when the directors wanted the mood dark and gray, we play our grays slightly blue-violet, " Kallianpur says. Kallianpur stayed involved with the look of the film all the way through color timing, and is thrilled with the result. "I have seen this film I don't know how many times, and it's just amazing, he says. "I'm biased, but it's really the most beautiful CG " film I have ever seen. " By successfully integrating 2D traditions into a CG world, one filled with technical challenges, the Disney artists have created a unique film and a certain classic. "I felt like a gift had landed in my lap, Goldberg says. "One " of the reasons I came to Disney was the promise of applying and blending the fantastic 2D aesthetic and design, those design principles, in a CG 3D medium. I felt we achieved that on this show. ■ CGW " Barbara Robertson is an award-winning writer and a contributing editor for CGW. She can be reached at BarbaraRR@comcast.net. Vancouver Film School ANIMATION & VISUAL EFFECTS C G W N ove mb e r / D e c e mb e r 2 013 ■ 15