When it comes to converting a 2-D movie to 3-D, there is a misconception that giving depth to a computer-animated film is as easily as checking an extra box before clicking "Save As." But Pixar's Bob Whitehill, a stereo supervisor who has spent the last year and a half with his team bringing "Finding Nemo 3-D" off the silver screen, can tell you that it's much more complicated than that.

MTV News spoke with Whitehill as a part of our Fall Movie Preview to learn all about what went into the process of bringing one of Pixar's most-beloved films into the third dimension.

Choosing "Nemo"
With such a stellar catalog of films, Pixar had a bevy of options for features to convert into 3-D, but as Whitehill told us, the audience chose "Finding Nemo" for them. "I think it was a combination of the fact that it was so successful, so beloved, and had such a worldwide audience," he said.

Aside from the success of the original release, the nature of "Finding Nemo" offered a unique opportunity for Pixar. "Creatively, ['Finding Nemo'] really lends itself so well to 3-D. Being down in the ocean, we have this wonderful particulate matter that gives a great sense of depth and volume," he said. "Having characters that float and hover makes it, on a shot-by-shot basis, great in 3-D. There are certain set pieces that play so well in 3-D, the jellyfish or inside the whale's mouth or the angler fish."

Particles Matter
An element of "Finding Nemo" that factored heavily into the conversion process is something you may never have noticed in the original film. Pixar filled each scene with what is called "particulate matter." It's the little specks that float in front of the camera and gave depth to scenes even before the 3-D conversion.

"In the original version of the film, it's animated in 3-D space. Luckily for us, they put this floating particulate matter in in 3-D, so it's in proper placement to the characters and the environment," Whitehill said. "When you go in there and set the 3-D for a character, all of the sudden, you've got all this particulate way in front of your face, too far in the audience space, as we call it. We had to go on a shot-by-shot basis and really cull it out or expand it or scale it or stretch it, so that it felt fully rewarding but not overwhelming."

Animated 3-D vs. Live Action 3-D
While converting an animated movie in 3-D is difficult, it doesn't require the kind of reassembly that the same work on a live-action movie would. " 'Nemo' was heavily in production a decade ago," Whitehill said. "Could you imagine going back to a live-action movie from a decade ago and reassembling all the actors today and getting all the lights in the same place? The same costumes? Make sure the actors haven't gained weight or look any different. You're re-filming it in 3-D. That would be impossible, but that's what we're able to do with something like 'Nemo' and 'Monsters.' "

Estimated Wait Time: Nine Months
Computer animation does make the conversion process easier in many respects, but it isn't a matter of simply re-opening the files from the original movie. Pixar constantly updates its software and file types, to the point where movies even a few years old aren't completely compatible with the current systems.

Thankfully, Pixar can update those files, but it can be a lengthy process. For "Finding Nemo," Whitehill and his team spend nine months updating the original files, bringing them up to the current standards. That's half the time of the entire 3-D conversion process.

Going Back In Time
How difficult it is to bring those files up to date depends on the film. Whitehill explained that there are two issues to consider: age and complexity. "With an older movie, say all the way back to 'Toy Story,' it's a less complicated movie. Just the number of characters, the number of sets is less complicated because it was early," he said. "But because it was so far back in time, it's complicated to get it up and running. There's a bit of a tradeoff. The closer the movies are to today's date, the easier it is to rekindle and get them back working in the software. Often times, they're more sophisticated and complicated, so they present other issues in that way. With both 'Nemo' and 'Monsters,' we're right in the middle of that curve."

From "Perks" to "Breaking Dawn, " "The Hobbit" to "Skyfall," the MTV Movies team is delving into the hottest upcoming flicks in our 2012 Fall Movie Preview. Check back daily for exclusive clips, photos and interviews with the films' biggest stars.