For Nolan and his team, it was important to use practical effects rather than computer graphics unless there was no other option. "The costs are about the same but it's a different look," explains production designer Crowley, who began strategizing with the director during the writing process almost a year before the shoot. "I feel quite strongly the audience can tell the difference between things that are animated and created in the computer and things that are photographed," says Nolan, though he didn't eschew CGI altogether.
"Typically, these films will have between 1,000 and 2,000 effects shots. We have about 650 visual effects shots, a lot of which are simple rig removals or things we can't achieve for reasons of cost or safety. We really blew up everything we could in the film," Nolan notes. "When you're dealing with an anarchist, somebody who is dedicated to chaos, the most visceral way of representing that is an explosion."
Not every explosion was doable, however. "When the Batmobile gets into a head-on collision with a garbage truck, I wanted to do that for real, but couldn't, and I had to accept that," Nolan says. "But rather than doing it with computer graphics, we did it with large-scale miniatures, and I think it cuts very seamlessly into the film."
Visual effects wizardry did come into play in creating the look of Two-Face's partly mangled visage, along with lots of completion and transition work. In a tense scene involving two ferries, "We built the dock and the front end of the ferries and extended them with CGI, but the loading platforms and the pier were real," Crowley reveals.
In another example of a composite sequence, "You have Batman on a building in Hong Kong. He jumps off that on green screen, and they comp in the background that we've shot in Hong Kong. We shoot some flying stuff on stage and they do some CG flying stuff and that's comped together. Then he's barrel vaulting through a window, and that's an interior built on a soundstage."
And in some instances, it's Christian Bale doing the stunts. "I do all of the fight sequences myself, although I do have a fantastic stunt double who is a great mixed-martial artist, but it wasn't necessary," he says, explaining that he's been well-versed in Keysi martial arts since he learned the technique on "Batman Begins." "It's a very instinctive kind of martial art. It's not about choreography; it's very much about using your adrenaline and becoming an animal in your fighting style."
Bale braved standing on the ledge of Chicago's Sears Tower himself, but when it came to jumping off buildings and crashing into a car, he literally let his double, Buster Reeves, take the fall. Similarly, stunt drivers took the wheels of the Batmobile and Bat-pod on camera. "You see the Batmobile jumping other cars and I'm quite happy to admit I'm not up to that level. And the Bat-pod, because of the huge wheels, there's only one man, Jean-Pierre Goy, who was able to control that thing and not fall off. So whenever you see me on it, I'm getting dragged behind another vehicle."
Bale nevertheless took any opportunity to take the Batmobile or Bruce Wayne's Lamborghini for a spin off camera. "I insisted it was absolutely necessary for my preparation," he deadpans.
The effects and stunts weren't the only challenge. Read on to find out about the difficulty of shooting in IMAX.