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n n n n Visual Effects (Left) This chase sequence, which takes place in a digitally altered tunnel, used a combination of real and digital vehicles, digital Death Eaters, the actors, stunt doubles, and digital doubles, all created at The Moving Picture Company. (Right) Shots such as this, for which MPC turned six actors into Daniel Radcliffe clones, helped overall VFX supe Tim Burke and MPC VFX supe Nicolas Aithadi earn Oscar nominations in January 2011 for Best Achievement in Visual Effects. we see six identical Harry Potters looking back. Before that, we see hybrids. Working from live-action plates of the ac- tors, MPC’s artists began by creating target concepts for each of the hybrids. “Te artwork ranged from subtle to cartoonish,” Aithadi says. “Because Tim [Burke] went for some- thing more subtle, our next step was to create CG humans for all the actors and do the trans- formation on the digital double.” To create the CG doubles, the crew decided to use Mova’s Contour System and capture the actors’ faces as they took breaks from filming. Before making that decision, though, they test- ed the system for a month. “We tried to break it, but it worked really well,” Aithadi says. On set, each of the actors stepped into the Contour rig and acted out a transformation. Some acted surprised, others expressed pain. Mova then processed the data and sent it to MPC, where riggers applied it to a facial rig. “Te facial features were really accurate,” Aithadi says, “And, the skin deformation. Te only problem was that they didn’t give us the eyes, so we ended up with a very good face and dead eyes that didn’t blink.” And, the crew discovered that the accuracy demanded was greater than anyone expected. “We underestimated how important the eye- lids were,” Aithadi says. “Because we were mixing characters together, every piece had to be good. It isn’t so much of a problem when you do one face—one George or one Harry. But you have to have good eyes to register Harry’s eyes with George’s nose. If you don’t fold the eyelids right, the eye looks weird. And the eyelashes. One millimeter can make a huge difference.” Blendshapes added to the rig gave animators the means to add blinks, squints, twitches, and eyelid folds to, in this example, Harry Potter’s (Radcliffe’s) eyes placed above George Weasley’s (Oliver Phelps’) nose. 34 January/February 2011 Te facial skin tones also had to be accu- rate, though most of the actors had darker skin than Radcliffe. “We changed the skin shader we usually use to get something that looked good close to camera,” Aithadi explains. “Ten it was a lot of trial and error to find out which shades worked best.” Once they had created a good blend, they deformed the faces. “Fleur [Clémence Poésy] was hardest,” Aithadi says. “She’s too perfect. We didn’t have much to grab onto.” After the transformation was complete, to create the illusion of seven different personali- ties “inside” Harry Potter’s face, Burke had each actor play out each role as if they were Harry Potter. Ten, Radcliffe copied those perfor- mances. “He did a fantastic job of picking up all their characteristics,” Burke says. “We shot him on a greenscreen set with motion control, and composited all the personalities together.” With the transformation complete, and the split screens composited, MPC mounted the six fake Harry Potters on brooms and Testrals, and slipped Harry into the side car of Hagrid’s (Robbie Coltrane’s) magical motorbike. ILM, which had previously created the skel- etal horse-like Testrals, provided MPC with the original models and textures, which MPC modified to accommodate two riders rather than one. On set, the actors rode real horses that MPC later replaced with the CG animals. As they take off, the point of view is Harry’s, and he sees chaos. “We have maybe 100 Death Eaters and a dozen good guys,” Aithadi says. “Everyone is fighting. And the sequence hap- pens within a big aerial environment.” To create the environment, the team ana- lyzed all the shots and divided them into back- grounds, mid-ground, and foregrounds. For extreme backgrounds, they produced matte paintings. For the mid-ground, they flew digital doubles through clouds created with Autodesk’s Maya fluids rendered in Mental Images’ Mental Ray, and through volumetric clouds rendered in Pixar’s RenderMan. “RenderMan gave us better detail for fly- ing through clouds,” Aithadi says. “Te details define the distance. From a distance, a cloud is fluffy, but when you fly through, it’s wispy, so we had to find ways to do that transition. When Harry flies away from Privet Drive, the environment is calm, serene. But, when he goes through a cloud, it’s hell. It’s a World War II extreme dogfight.” Inside the clouds, the young wizards— digital doubles from afar and live-action elements when close—and the evil, digital Death Eaters fire spells at one another, and the spells light the volumetric clouds. Simulation times for the cloud volumes ranged from 10 to 20 hours per frame, with rendering often taking two days. Te crew rendered the clouds with passes that had different directions for lighting, and then composited the shots in Te Foundry’s Nuke. “We didn’t want to get a cloud plate and stick people in there,” Aithadi says. “We really wanted to play with the light and the depth. Nuke allowed us to create more of a 3D feel with the 2D elements as well. Te compositors became more like environment technical directors.” Road Rage To escape, Hagrid uses dragon fire, a massive burst of CG flame nearly a mile long that rockets the bike and sidecar. To create it, MPC used Scanline’s Flowline. “It’s the longest sim- ulation I have experienced in my life,” Aithadi says. “It took ages to simulate, maybe a week and a half. It’s extremely detailed.” Te camera moves into the fire, and when it emerges, we see Hagrid and Harry speeding on a real-world highway toward the Dartford Tunnel outside London. MPC built the envi- ronment in CG using photographs of the en- trance and the tunnel. “Te only real things are the cars and the tarmac,” Aithadi says. “Tey closed the tunnel for two nights so we could shoot stunt cars. We also shot stunt doubles