When you’re creating a blockbuster with thousands of CGI-generated extras, you do need a technique that will allow you to previsualize the stuff you’re going to shoot. Certain scenes from recent productions (Star Wars: Return of the Sith, LOTR Trilogy, etc.) are so complex and costly that no sane producer will agree that you spend the budget “experimenting” on location. Here’s where sophisticated 3D tools kick in:

“You can experience directing a big action scene and assemble it without getting out there, without spending any money,” says visual-effects supervisor Robert Legato, an Oscar winner for his work on James Cameron’s 1997 epic “Titanic.” “You have a shot list, a rig list, camera angles, and you can organize your shooting days.”

You can read the complete article on Previsualization at the Hollywood Reporter.

If you’re interested in a more “visual” experience, you can get the Making of Star Wars: Return of the Sith DVD where you can watch the bonus DVD extra – Within a Minute. Looking at some of the stunts being polished is like looking at a small scale video production: they shoot with a Canon XL1S and use a wheel chair as a dolly. Lucas loves indie filmmaking.