Third Magazine

2D to 3D Conversion – How is it done?

Posted on 01. Feb, 2010 by The James in Industry, Theaters

There is a great article over at Slate discussing the process of converting 2D footage to 3D footage.  During the current 3D boom, a lot of feature films will be converted rather than shot in two camera stereoscopic style.  This includes Tim Burton’s upcoming “Alice in Wonderland”.  Here’s a bit on how the conversion process works:

The first step is to separate the shot into somewhere between two and eight layers of depth. Take, for example, an image of a man standing in front of a brick wall, with a blue sky behind the wall. The graphic artist might separate the shot into three layers: the man, the wall, and the sky. Then, he would take each layer and draw contour lines around any object that appeared there. He’d start by marking depth lines on the man using a computer, turning the image into a sort of topographical map. He’d repeat the process for any objects in the other layers.

Once this is done, the computer takes over. Software creates a new, offset image of the man by moving the various regions of the contour map to the left or right and smoothing everything out. The closer bits—the tip of the man’s nose, for example—would be moved the farthest, while the more distant parts—the back of his shoulder—would be displaced a bit less. Then the process would be repeated for the other two layers of the image: the wall and the sky.

There seems to be some petty arguments about converting 2D to 3D versus shooting stereoscopic.  James Cameron is on record criticizing Tim Burton for his choice of conversion.  I can’t help but snicker at the irony here.  Mr. Cameron, do you really have room to poke at someone for not using “true” 3D shooting when 90% of your film Avatar was CG anyway?  Is there really a difference?  All those characters had to be rendered and animated, so whether or not two cameras were used, the image is still “faked”.  I’ve personally had the opportunity to view 3D that was created both by a conversion process and by true stereoscopic dual cameras (4k Reds), and the difference is pretty much unnoticeable.  And it impossible to tell the difference when you factor in animation and lots of CG.  Dual camera options will become more common as the 3D process becomes more familiar with directors and shooters, until then, conversion looks pretty good in my opinion.

Tags: 3D Conversion