Computer Graphics World

August 2009 Moving in Stereo I n my job as 3D effects supervisor on a wide variety of stereo- scopic projects at Sony Pictures Imageworks, I have been for- tunate to have witnessed firsthand the emergence of a differ- ent kind of cinematic medium. While stereoscopic imaging can be traced back to the mid-1800s and the invention of the first stereoscope, it wasn't until the recent advent of digital production techniques and digital exhibition tools that the ability to create and present truly high-quality 3D has become possible. During the past five years, I have had several moments when my expectations for the possibility of 3D entertainment have been e xpanded. My first eureka moment came in 2004 when I saw the test images for e Polar Express: IMAX 3D Experience. It was then that my expectation for what a cinematic experience could be was forever transformed. ere are those who think of 3D films and believe they are a "gimmick" and, oftentimes, associate their poor, headache-inducing experiences watching anaglyph (red/cyan) home-video releases (and, sadly, some theatrical releases) with modern 3D. Anyone who has seen a modern 3D film projected either in an IMAX theater or with digital projection knows that the medium has the power to connect you with characters and into the action in ways that are impossible with traditional cinema. It should be made clear, though, that it is a different medium and one that deserves and demands a different set of rules and cinematic language. Approaching 3D filmmaking using strictly 2D thinking will not lead to the real breakthroughs that are just on the horizon. My second eureka moment came just last year when I saw the concert film U2 3D chronicling the Vertigo concert tour of the iconic rock band. e film featured multiple layers of imagery at different depths and 3D graphical elements that wouldn't typically belong in a narrative film but, in this case, allowed it to transcend the term "concert film." I believe the film should be viewed as a key step in the innovation of stereoscopic filmmaking. For Disney and Jerry Bruckheimer's G-Force, director Hoyt Yeatman came to Imageworks to create the digital visual effects and animation, bringing the hero guinea pigs and their gadgets to life (see "Pushing the Bounds," pg. 18). e film's subject mat- ter spans a wide range of scales, including everything from a tiny housefly to an eight-inch-tall guinea pig and an 80-foot-tall killer robot (yes, this film has giant killer robots, too). In order to capture this action, Yeatman deemed it important to be able to film using traditional 2D camera rigs and not be limited by existing 3D camera technology. With that decision made, he came to us again to discuss a postproduction process to convert the plate photography and integrate the visual effects elements into the resulting stereoscopic image. While a postproduction process had been used before on already-completed films (notably on e Nightmare Before Christmas), nobody had attempted a day-and- date-release of a feature film using a mix of converted photography and true stereoscopic elements. With about three-quarters of the running time of the film fea- turing visual effects already being executed at Imageworks, it was a natural fit for us to tackle the stereoscopic adaptation, farming out the remaining work to two other facilities. With this ap- proach, for the 3D release of G-Force, every shot in the film is now a visual effect in which the second eye's viewpoint has been created u sing information from the original photography. At a very high level, the process consisted of isolating all the elements within the shot, offsetting them through projection or 2D techniques and then filling in the holes created by revealing occluded regions. For shots featuring guinea pigs, for example, the additional step of ren- dering the character from the other viewpoint and integrating it into the dimensional plate would complete the effect. e end result of using this technique is that we have freed the director to use all the tools and techniques for 2D plate photog- raphy developed over the past 100+ years of filmmaking and have also allowed the depth choices for each shot to be deferred until p ostproduction. While good composition is still important during StereoScopy By Rob EnglE Rob Engle is 3D effects supervisor at Sony Pictures Imageworks, where he most recently worked on the stereo feature G-Force.

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