Computer Graphics World

July / August 2016

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10 cgw j u ly . a u g u s t 2 0 1 6 human. To get their humanity right, we had to level up in a lot of areas." Those areas included skin shading, fa- cial capture, hair grooming and simulation, and lighting. B E A U T Y I S S K I N D E E P For Warcraft, ILM artists used Pixar's RenderMan – the Reyes version, not the newer RIS version. "We started development three years ago," Smith says. "We were definitely still a Reyes show." The advances they made in skin shading were more artistic than technical. "The developments we made were in tuning the skin relative to real-world photography," Smith says. "We started with photo reference of a real person and looked at how much red was bleeding across the line, the transition from sunlit to shadow. When we compared our skin to the photographs, we found that our scatter [subsurface scattering color] tended to be a little too neutral. If we didn't have enough red in the scatter, enough blood, the skin felt like wax and it was all one color. So we really pushed the input to the system. At a certain depth, the scattering picks up a nice red hue and it warms the skin." Some of the Orcs are colored green, and for those, the artists used yellow rather than red. "Jeff [White] and I lived this already with the Hulk. If you scat- ter green, the skin really does look like silicone. If you add red, it looks gray. What we found on Hulk is that the right way to approach scattering is to think about adding warmth. On a green person, that's by moving toward yellow." As they had done for Hulk, the crew took a life cast of an actor, Robert Kazinsky in this case, who plays the character Orgrim, and from that extracted pore-level detail. M O T I O N C A P T U R E ILM has perfected its method for on-set motion capture since first using IMocap for Davy Jones in Pirates of the Caribbean: Dead Man's Chest. "On this film, we would be working indoors on soundstages, so we decid- ed to get the best of both worlds," says Animation Supervisor Hal Hickel. Because the greenscreen sets were enormous, the motion-capture team was able to hide cameras in the large trees and other props to create a motion-capture volume as they would on a typical motion-capture stage. "We designed the system around captur- ing the performances in the environment," White says. "We wanted to get the reaction to the environment in the actors' faces." The actors wore suits with active and pas- sive retro-reflective markers. Director Jones could see the characters visualized on set. "We'd get a great mocap performance," Jones says. "The actors would leave. And we'd play back the low-res version of what the characters had done. We could see the shots and recompose them to move the camera around or get it into a close-up." Riggers assigned each Orc a skeleton based on the shape of its outer geometry, using a system named BlockParty. The creature's muscles moved based on its performance; simulation changed the muscle stiffness. For facial capture and animation, the actors wore a helmet with cameras pointed at their faces. The motion-capture and animation teams at ILM then used an up- dated version of the studio's Muse soware, which had been developed for Turtles, to move the data onto the CG characters. "Turtles had more demand for editabili- ty," Smith says, "for splicing different takes. Our goal was to translate the performance directly from the actors." For the humanoid Warcra characters, the crew referenced their work on Davy Jones, for which Hickel had received an Oscar for Best Visual Effects. "The key to our work on Warcra was the philosophy we developed and the things we learned working with [Davy Jones actor] Bill Nighy," Hickel says. "Some people want to change everything: Start with the first line of one take, then use the third line of another. Duncan [Jones, director] calls the result a Frankenstein performance. We found the more you do that, the less believable and authentic the performance feels. There is a dense web of connections between the expres- sions on an actor's face and their body language. The tilt of a head, a blink all add up to something that starts to not work anymore if you rearrange it. We treated motion capture as live action. What you get on the day is what you get. We don't stomp on it and modify it. We carry it like a fragile thing through the process." To accomplish that, ILM built a CG version of each actor who would be motion-cap- tured, and before moving data onto their Orc character, the crew first applied the data to their CG doppelganger. Only when satis- fied that the data caught the actor's facial

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