Issue link: https://digital.copcomm.com/i/739236
10 cgw s e p t e m b e r . o c t o b e r 2 0 1 6 to make sure the detail could render for the length of the film. There is lots of fuzziness in the film – the trolls, the other crea- tures, the world around them." Level of detail helped manage the rendering requirements. DreamWorks uses a proprietary scan-line renderer. "When the trolls are away from camera and small, we use displacement," Denis says. "When they're close enough to see the fuzz, we use a fur shader." The crew handled elements in the environment similarly. Trees, for example, might be geometry with fur shaders or displacement. "When the camera pulls back, the texture becomes just displacement," Denis explains. "But the shader had to respond to the light, so the trees still seemed like felt, not plastic. Every time I did surfac- ing rounds, I knew we were in good shape when I wanted to touch the fuzzy thing. It became a checkpoint." S E T T I N G T H E T O N E The biggest challenge for the effects crew, though, was the number of sets. There's the troll village, Bergen town, and many environments between. "The challenge and the fun was that our effects needed to fit into this kind of handmade world. Almost like a stop-mo- tion world," Denis says. "Our grass was felt. Our fire looks like hair. Our hair looks like fire. For dust, we use a little piece of fuzz. And we made the tree roots from a sheet of gauze- like fabric. It isn't stop motion. There's blur. But there is a little feel of that." Throughout the film, the crew used shallow depth of field, matte paintings, and digital matte paintings – projections onto 3D geometry – whenever possible to reduce the render- ing load. During one musical sequence, for example, Poppy travels through 27 different environments. "We had almost one envi- ronment per shot," Denis says. "It was very graphic. Each beat had a different color. It becomes more abstract as she leaves the troll village, and then gets totally abstract. Really colorful – but, with only one or two colors for a simple read." On the other hand, for a se- quence set in the troll village, the artists have Poppy sing in several unique, fully lit, fully surfaced 3D sets. Throughout the film, music carries the narrative, with songs selected by the directors with help from Music Produc- er and Branch's voice, Justin Timberlake. "It was a musical from the in- ception," Mitchell says. "If you're doing a film about happiness, you need singing and dancing." "Of course, the trolls would be full of song," Dohrn says, "colorful music to tap into im- mediate emotion. Plus, there's a great tradition of using music in animation. Our music is non-traditional, but our film has its roots in animated musicals." "We had to do it in a way that the musical numbers didn't stop the story," Mitchell says. ANIMATORS STRETCHED, SHAPED, AND PLACED THE TROLLS' HAIR USING GUIDE CURVES SO IT COULD BE USED IN EXTREME WAYS. HAIR WAS ALSO A DESIGN ELEMENT IN THE TROLLS' WORLD.