Alice in Wonderland presented a high degree of difficulty for veteran VFX master Ken Ralston and director Tim Burton, who tends to prefer live action FX to digital ones. He clearly wrestled with the huge volume of CG effects—the film used far more green screen than he’s ever dealt with. “It starts freaking you out after a while,” he said at Comic-Con, admitting that Alice in Wonderland was “the most difficult” movie he’s ever done. Burton insisted on avoiding motion-capture as much as possible (the effects team did mo-cap some actors, for reference). Burton wound up favoring “pure animation and using actors in mysterious ways,” he said.
Alice in Wonderland managed to score a final visual effects Oscar slot against intense competition this year. That's because the VFX are all-pervasive throughout the film, and are used in ingenious ways to mix and match live-action footage, exacting exercises in shifting scale, and key animation. "It's one of the most complicated things I have ever been involved with," says Ralston, who is prepping Men in Black 3. "At first Burton was wary. But the great thing is, we hit if off. We didn't dwell on the technical. We'd just get it done. He wanted real props there to give the actors something to work with. The hardest thing is the combination of creating a virtual world and adding action props so you believe that live actors are in that place. It's complex, taking live actors who are talking to eccentric fantasy characters, to give a sense of relationship, to make them look like they are there."
More exclusive details and how-they-did-it photos are below.
When tiny six-inch Alice rides on the Mad Hatter's top hat, a complex program translated Johnny Depp's walking movements to a moving giant prop hat brim on which actress Mia Wasikowska was standing and falls off to land on a giant shoulder piece. But in another part of the scene, the wide-shot of Alice running across the tea party table is digital.
Similarly, when Alice battles The Jabberwocky, her close-ups are live Wasikowska on a wire rig, but the wide shot is strictly digital. The most confounding aspect of this shoot was the constantly shifting scale of the characters. "There were so many scale changes," says Ralston. "Alice is six inches, two feet, and 8 1/2 feet. She's barely ever a normal size. It all has to look as if it is happening in front of you at that moment."
Most of the film is an artful blend of hybrid live-action and animation, live actors and digital doubles. Ralston says that along with green screen, Sony Imageworks used painted murals and reflective glass surfaces; digital environments were highly detailed renderings, complete with dust motes.
Tweedledum and Tweedledee were shot as padded actors walking against a green screen (the digital environment was added later), who were then rendered by animators.
The trickiest feat of VFX magic, says Ralston, was the "so insane" Red Queen. "We had to fight to find the right look." Finally Helena Bonham-Carter's head was enlarged 175 % to be much bigger than it really is--and then had to be artfully balanced-- with hair, nape of neck and high collar--on the Queen's digital body. "You have to feel that it is resting on her shoulders," says Ralston. Animators gave her an hourglass waist to balance her proportions. Also digitally enlarged were Depp's Mad Hatter eyes, which morph into the digital green-eyed Cheshire Cat at one point, who appears in a gloomy forest with moody lighting.
Christian Glover rode stilts on the set to give Stayne seven-foot height, but animators used that footage to place him properly in the frame. He rode a horse rig, but on-screen, his horse is digital, and on set he caressed a stick with a blob on top--which became a CG dog. The Bandersnatch and March Hare are also digital.
Ralston likes how the movie looks in 2-D. (My stance is to see every movie in the form in which it was shot, and this was shot in 2-D and transformed into 3-D after the fact.) He admits to certain 3-D sacrifices in color-correction, but says that "3-D gives us another tool to help believe the characters are in spatial environments, to get inside of it instead of plastered on it."
Finally, as difficult as it was, Burton and Ralston like how Alice came together. "It's one of my best creative experiences on film," says Ralston, who admits that at Sony Imageworks, "every day has its share of terror."
See more on the VFX here.