The New York Times has an excellent article that describes the process that Toy Story and Toy Story 2 underwent at Pixar Animation Studios for their 3D re-release:

The production process for a 3-D movie requires the use of two cameras, positioned next to each other, shooting action at the same time to mimic each of the viewer’s eyes. A live-action film not originally shot with two cameras cannot be made into a 3-D film, but in the more malleable world of computer animation, the second camera view can be added. The process involves a bit of virtual time travel.

Without changing any of the film’s action, Pixar’s 3-D specialists, or stereographers, returned to each frame of the film and virtually placed a second camera next to the original, creating left-eye and right-eye views of the scene. Then all of the scenes were re-rendered in the computer with this additional perspective.

Head over the NYTimes.com to read the entire article.

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