Computer Graphics World

November 2008 19 Stereoscopy n n n n tracks had to match perfectly." Similarly, rotoscoped images needed to match perfectly, even though the original images might not. For example: "e cam- era views of Brendon Fraser's hair might be slightly different," says Shand. "You might see a curl of hair in the left-eye image but not in the right-eye image. at confuses the viewer's brain and causes what I call buzzing. So, the artists had to tweak the images by hand." Specular highlights captured by the camera were often different for the left and right eyes, as were lens distortions and col- ors. "e biggest things that would make this process easier would be if the camera systems produced footage that was more identical in color," Shand says, "and, if we could improve the interocular tracking." As do filmmakers working with 3D animation, Frantic's visual effects crew used the distance between the cameras as a storytelling device for their largely digital shots. "If you increase the distance, things effectively look small, as if you were a gi- ant," Harvey says. "If you do the reverse, everything feels bigger and more impos- ing. So, we constantly shifted interocular distance and convergence to tell the story. We did a lot of adjusting—literally sliding the images left or right." In doing so, the crew quickly discovered that making those adjustments on a com- puter screen wasn't sufficient. "You have to look at these images big," Harvey says. "To get things to sit properly in stereo, we were moving things at a sub-pixel level." For example, differences in the live-action images sometimes caused ghosting. "Ghost- ing happens when high-contrast areas close to each other are at different depths," Har- vey says. "It causes buzzing in your eyes, and it's hard to resolve. If you're working only in CG, you can move the images onto a zero plane with no convergence—the left and right images are the same. In live ac- tion, what was shot is what was shot." At Weta Digital, where work on Camer- on's Avatar is ongoing, Matt Welford, com- positing head, is running into some of the same challenges. "Often, we find that pull- ing a key for the left eye will not work for the right because of differences in lighting," he says. "We have to make sure the quality is perfect for both eyes, but the cameras are looking in slightly different areas." at makes the job of painting the im- ages much more difficult. "Hand painting on a single view is already difficult," Wel- ford says. "But now, if we have to remove something from a scene and hand-paint the image, we're painting a very specific depth. If we put something in a slightly different depth for one eye, we throw the stereo off. We had to toss a lot of the tips and tricks we used to use out the win- dow. However, it's good to be doing something new and different." Moving Deeper Welford is certain that although the studio will solve some of the com- plex problems in the next few years, creating hybrid live-action/CG films, such as those he's working on, won't become a push-but- ton process anytime soon. "I think maybe for people working in fully CG movies, it will be easier to make 3D a process, but it will take a long time for people working with live-action stereo films to develop automated processes that will be at a standard that's acceptable for final production." Even so, Imageworks' Engle believes that the choice to make a 3D film will eventual- ly become as insignificant as the choice be- tween filming in color or black and white. "We have three hurdles to overcome," En- gle says. "One, audience acceptance among adults as much as kids. Two, filmmaker ac- ceptance—not every filmmaker is as excited as Burton, Spielberg, Zemeckis, and Cam- eron. It remains to be seen at what stage ev- eryone jumps onboard, and that may never happen. And three, making the decision a no-brainer. We're not there yet. We have a lot of work to do with tools, but what we're really missing right now is experience. e visual language is still evolving." What might we see in the future as stereographers such as Engle, McNally, Neuman, and various directors and visual effects supervisors continue exploring the possibilities? Engle offers a few thoughts: "So far, everyone is using 3D as a repre- sentational experience," he says. "ey're mimicking reality. Why do we need to do that? I think there is a filmmaker out there who will make a revolutionary movie— someone who will really push the technol- ogy. Someone who will break the rules." McNally is looking in that direction, too. "You don't expect a painting to be a photo- graph," he says. "You expect to see the me- dium. What does it mean when we're in a full three-dimensional spatial delivery of a story?" at's what is so exciting. We have an undiscovered medium." But with 5000 3D theaters in the offing and directors readying new content, it's a medium that's ready for its close-up. n Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net. Disney's 2005 animation Chicken Little was the first stereo 3D film shown in 84 theaters newly equipped with RealD projectors. Experts estimate that in the first-quarter 2009, approximately 3000 North American theaters will be stereo 3D-ready.

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