I’ve been saying for years that the best CGI scenes are the ones you don’t notice.
Almost exactly 18 years ago I wrote a Reel.com piece about a sleight-of-hand car crash sequence in Steven Soderbergh‘s Erin Brockovich. No one spotted it at first, and yet, if you thought about it, the scene had to involve exceptional trickery because a single uncut shot showed Julia Roberts getting into her beater, driving toward an intersection and getting totally rammed and spun around by another car. Roberts would’ve obviously been badly hurt if she’d been driving and yet she wasn’t. So how did they pull it off?
The shot was achieved by seamlessly blending two pieces of footage — one of Roberts getting into the crummy-looking car and slowly driving off, and a second starring a Roberts dummy (wig and all) behind the wheel only this time in a radio-controlled duplicate of the same car. (Or it was all one car — what do I know?) The real Roberts transitions into the Roberts dummy right around the 41-second mark, or just as her car’s structural divide section (i.e., the metal section between the front passenger window and the back seat) passes in front of the camera.
An excerpt from my original article: The alchemist was Tom Smith of Cinesite, a leading visual-effects company known for creating certain highly convincing illusions in Wild Wild West, Message in a Bottle, Armageddon and For Love of the Game.
“It’s what we call the A and B side of a shot,” Smith explains. “The first shot is of Julia getting into the car, starting it up and driving into traffic. Right when the camera is looking at her as she passes by, we stretched and blended this with footage of the Julia dummy behind the wheel of the radio-controlled car. The transition happens over a small number of frames, then we stayed with the dummy car all the way until the accident.”
Viewers might be able to notice the transition between the two Julias and the two cars when they watch this scene next fall on the DVD, says Smith. “There are very subtle differences,” he says. “The Julia dummy has a couple of hairs in the wrong position, but you can barely tell.”