Unlike megablockbuster Avatar, Alice wasn't filmed with a stereoscopic camera rig; instead, it was shot with traditional cameras and converted after the fact. This is because Burton felt it would be less time-consuming given the film's potpourri of effectsmanipulated live action (the Red Queen's bulbous head), rotoscoping (the Red Knave's movement) and completely computer-generated characters and backgrounds. Instead, a team at Sony Imageworks headed by visual-effects supervisor Ken Ralston was tasked with creating the three-dimensional Wonderland. "What helps the audience feel as if Alice is in this world is part of that false sense of depth, the spacial relationship to what she's running around in," Ralston says. "When she's in a mushroom forest heading for a caterpillar, 3D is one more way of making you feel as if she is standing out there with the Tweedles, with the Caterpillar and the smoke wafting around. It seemed to be a natural fit. We weren't forcing the 3D down anyone's throat; it really helps you feel as if you are in Wonderland."
While in Wonderlandor Underland, as it's called in the filmAlice is constantly changing size, shrinking to fit through a tiny door and growing into a giant to impress the bossy Red Queen, whose huge head leads her to love anything larger than life. Filmmakers used the 3D to enhance the effect, putting the camera down low as she grew taller and shooting from above to show the sheer size of the things around her as she shrank. "There are so many scale changes where she's 6 inches or 2 feet tall or giant," Ralston says. "3D was beautiful for those shots."
Sometimes, visual-effects artists manipulated the 3D to make the audience feel what Alice was experiencing. When Alice teeters on the edge of crumbling ruins while facing off against the jaw-snapping Jabberwocky (modeled after some of Ray Harryhausen's stop-motion work), the camera shows her point of viewstraight downand you're right there with her. When Alice is trapped in a teacup, you feel that, too. "If Alice was trapped, we made sure the depth was more compressed," Ralston says. "Or if it was a big, wide scene, then we let you feel a little more of the distance there. You can do a lot of that stuff with 3D."
And then there are shots reminiscent of old stereoscopic films, where objects fly off the screen toward the viewer. While most filmmakers believe that such effects are gimmicks, preferring to make the experience more immersive and less intrusive, Ralston says they wanted those shots in the film. "In fact, in the beginning Tim was probably thinking we'd do less silly stuff," Ralston says. "And then we ended up doing Red Knights poking spears at the lens. We wanted to have more fun with it. When we grew up, there wasn't much 3D, but what was done was so silly, and this is an homage to those movies."
But making a stereoscopic film came with its own set of challenges. "As hard as you push 3D, it can never be too extreme or your eyes get pulled out of your head," Ralston says. Making settings for interaxial distancethe space between the two cameras that represent the human eyes and create the illusion of depthtoo intense can lead to an uncomfortable experience for the viewer. A good example of extreme depth done well in the film, Ralston says, "is the shot where you're looking at a dew drop on a mushroom, and you can see the upside down reflection of the Tweedles and Alice walking towards the Dodo Bird. The camera drops down from that and we see them behind it. That was an extreme depth."
Even placing digital elements too close to the camera can look odd to the audience. "There are so many things you have to look out for while doing this so it doesn't look funny," Ralston says. "Small things on the edge of the frame can work better in 3D than a big objectthat can look very strange. And until you see it you're not quite sure why. Some of those considerations came into play in terms of what we could have in the foregrounds and backgrounds."
While he acknowledges that working in 3D was toughand created a lot more work for the VFX artistsRalston is thrilled with the result. "It worked a lot better than we thought it would," he says. "It's just one more great tool if you can use it right. I enjoyed using it. Creatively, 3D was a great thing to have."