The next trick, Pace says, is to make sure that the cameras communicate with each other so that the images they capture aren't radically different in terms of zoom or focus, for instance. The cameras used for Journey were essentially networked, he says, with specialized software that monitored the input of both and dynamically adjusted them so that they matched each other. The software controls nine parameters: the zoom, focus, and aperture (the amount of light admitted) of each camera; the framing of the zoom function, so that it's the same for both cameras; and the relative angle of the cameras.

Once Journey was shot, it was essentially two separate movies: one for the right eye, and one for the left, says Lowry, who cleans up some of the artifacts that inevitably occur when shooting in 3-D. Because one camera is shooting directly, and the other is shooting from a reflection off a mirror, the images aren't equivalent. The reflected image has lost a little light and is thus of slightly lower resolution than the direct image, Lowry says. Using the horsepower of about 720 computers specialized for processing imagery, Lowry Digital adds resolution to the movie file that contains the reflected images. Lowry explains that this is done by extracting information from multiple frames. "You can find detail that's hidden in the grain or noise of a camera," he says.

Electrical noise is another important consideration--especially under low-light conditions, when the signal from a camera's digital sensors is weak. Lowry says that the footage from Journey had a lot of noise because in a number of scenes, the main source of light was the headlamps on the characters. If part of a scene has the graininess caused by noise, while another, well-lit part is crisp, the 3-D effect can be lost or, worse, annoying. To solve this problem, the image-processing software again adds resolution to frames whose darker areas might be too grainy.

For all the apparent trouble of making a 3-D movie, the industry is investing in the technology. Lowry notes that this year, there have been six 3-D movies, and next year, about 17 3-D releases are planned. "It's in a state of growth that's quite remarkable," he says.