Issue link: https://digital.copcomm.com/i/863766
34 cgw j u ly . a u g u s t 2 0 1 7 F E A T U R E the performance of actors atop horses with saddles and stirrups, which was translated onto apes riding bareback. "That motion tended to look a bit off because the actors were taking weight, even minimally, on their feet, and that was not translated on the screen," says Barrett. Evolution, however, helped resolve this problem in War: The apes have evolved in their relationship with horses and have developed their own tack. As a result, the captured motion translated more intuitively onto the CG apes. Fur-Real Perhaps one of the biggest improvements on this film pertains to the fur grooms. "We pushed our fur technology quite a bit be- tween Dawn and War," says Lemmon, noting much of that resulted from work Weta did for The Jungle Book on King Louie and the monkeys. "That gave us a chance to push our grooming tools to the next level." The artists did a re-grooming pass on all the recurring characters. In terms of volume, Lemmon estimates that most of the characters have two to three times as many strands of hair now as they did in Dawn. Although the count varies from character to character, Caesar has close to a million hairs now; some of the denser- covered cast has between three million and 10 million hairs. "We are also clumping and styling the hair in a way that is more realistic, closer to what we see in nature" Lemmon says. More complicated environmental condi- tions introduced new levels of interaction and visual complexity as to how the fur behaves. In addition to dirt and rain, harsh winter wind and snow (freshly fallen flakes, melting snow, and so forth) have been added to the mix. These elements needed to realistically alter the texture and color of the fur and integrate into the simulation of the individual hair movement. "Snow on fur is something we hadn't really done before," says Lemmon. "The apes walk through the snow. There's falling snow that sticks to their fur, clumps, and falls off. They roll around in the snow in one sequence. Having that interaction between the snow and fur, and transferring the snow from the air, ground, and back onto the character's fur was a big deal that forced a change in our fur grooming system and our dynamics system." As a result, Weta rewrote sections of its hair engine, Wig, to allow it to integrate more seamlessly with the studio's simulation soware, Synapse. As a result, data could be passed back and forth between the two systems to create more sophisticated styling tools for the fur. "It wasn't just about getting dynamics in participating media like snow onto the fur, but was also about using some of the simulation tools to isolate, style, and attach parameters to the hair in different ways," Lemmon explains. "It gave us more flexibility in our core styling tools and in our simulations." Lighting conditions ranging from sterile winter exteriors to warm flame-lit cave en- vironments also demanded realistic-looking fur. As a result, Weta moved away from Pixar's RenderMan, which was mostly used for Dawn, and rendered War entirely through Manuka, the studio's new ray-tracing engine. By doing so, the artists can model the transport of light through the hairs and the shadowing of the hair back onto the skin far more accurately and realistically. TDs also rewrote the shader. "We moved to a dual-core model. In addition to modeling the hair strand with all the scales and the way the light breaks up, we model the cuticle and the medulla, so there is an inner core to the hair," explains Lemmon. "That gives us a lot more realistic transfer of light through the hair, and we get a lot better glint and breakup, particularly in backlighting situations. That is what we struggled with in Jungle Book." Moreover, a system built on top of Manu- ka, called PhysLight, enables the artists to accurately model the way the cameras pick up and respond to light. As a result, they IN WAR, HALF THE HORSES ARE CG, THE OTHER HALF TAKEN FROM PLATES. FOR THIS FILM, WETA ALSO IMPROVED ON THE CG HORSE MODELS AND THE DYNAMICS BETWEEN THE HORSES AND RIDERS.