G-Force, the action/comendy about a government agency of guinea pigs that save the world, opened recently.  It’s a fully-3D movie, but didn’t start out that way.  Four months into shooting regular 2D film, a change of course requiring some fairly extensive rethinking.

So principle photography on G-Force, produced by Jerry Bruckheimer, proceeded as it does on most movie sets—in two dimensions. But four months into shooting the film, Disney asked if Yeatman could make G-Force in 3D. Yeatman turned to VFX house Sony Pictures Imageworks, which was already creating the film’s animated guinea pigs, to figure out how to do it. “We said, ‘there is this technique we can use,'” says Rob Engle, 3D visual-effects supervisor at Imageworks. Known as dimensionalizing, it’s when artists take a 2D image and pick the layers where they want to create depth—and it’s all done by hand. The technique gave Yeatman the control he wanted over the stereo settings in postproduction. “It’s the first time a feature-length movie has been dimensionalized in this way,” he says.

via G-Force Movie 3D Effects – New G-Force Movie – Popular Mechanics.