You know, it still startles me when I see a commercial or a movie preview and, after taking it for granted that a particular video clip was accomplished through live-action filming, I discover that it was, instead, entirely computer-generated. It looked too real, too detailed; not so very long ago, 3D animation was as easy to differentiate from reality as 2D animation. Now, it can take a sharp eye to tell the difference.

As 3D modeling technology grows more and more advanced, the line between reality and digital renderings becomes ever more blurred. At times it's impossible to tell CGI art from a photograph, and now even computer-generated motion is approaching startlingly detailed levels of reality. But just how do they do it? Here's a look at the technology behind applying realistic motion to fantasy characters.