Inside 'The Dark Knight'

­Since Chicago became Gotham City in "Batman Begins," returning there for "The Dark Knight" made perfect sense. Not only was the city accommodating to the production, "It has an enormous amount of wonderful architecture in a very small area, a lot of modernism plus turn of the century classic buildings, so when you photograph it you get a bit of everything," notes production designer Nathan Crowley. Bruce Wayne/Batman's home, Wayne Manor, burned down in "Batman Begins," "So it was a great excuse to put everything in town and with that came a modernist city, with clean lines, to make you feel that it's a more hard-edged place."

Taking over downtown Chicago for 12 weeks was made easier by cooperation from city agencies, but was a difficult proposition. "We were having to close down streets," points out producer Emma Thomas. "They let us take over their financial district at night as long as we were safe, and they made sure that we were," adds producer Charles Roven, though he reveals one mishap invol­ving the Bat-pod cycle.

"It came out of an alley onto the street and created a huge sonic boom that blew out a bunch of windows in a building. That was not planned. But we mobilized glaziers and within 24 hours we had fixed every window."

Careful planning avoided potential disaster in flipping that semi truck on La Salle Street, which Crowley describes as "a narrow canyon of historic buildings. Then you have city sewers and electric cabling below the road, so there were a lot of logistics. You plan, you test and you do it once."

Similarly, there was no room for error in a scene where The Joker blows up a hospital. A vacant building in Cicero, Ill., that was slated to be demolished was the perfect stand-in, once it was dressed with the proper facade and signage.

The production used another vacant building, a former post office, for the opening bank robbery sequence, but the film also took over spaces currently in use. "The boardroom was an existing floor in the IBM building that we refitted. We wanted to have a real view outside the window," Crowley explains. "You're dealing with building management so there's a lot of negotiation."

That was also the case in Hong Kong, where, according to Roven, it took nine months to get the permits needed to shoot there. "What we were doing there was complicated, and we were doing it in very highly populated centers. A lot of it had to do with big action set pieces with a lot of vehicles," he explains.

Twice during production, filming moved to locations in England, including Cardington, Bedford, Pinewood and Leavesden Studios, and London. "There's an enormous old airship hangar that the British government used to test concrete and steel, and there's two existing buildings within it," notes Crowley. For a climactic high-rise sequence, "We intercut footage shot there with the exterior of a building under construction in Chicago."

Despite all the outdoor shooting in that city, weather didn't prove to be an obstacle, according to the producers. "We were very lucky that we were there in the summer. It was hot during the day, but we were shooting at night," says Thomas. "The only problem with that was the nights were short," adds Roven. "We had to wait till almost 9:00 and it was starting to get light by four in the morning."

Keep reading to learn more behind the scenes secrets about the special effects in "The Dark Knight."

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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.

Christopher Nolan wanted to make a film in IMAX for years but waited until he had the right project, and he did a lot of research and preparation going into it. "We thought it would be very cumbersome, very tricky, very time consuming, so by the time we arrived on set we had it pretty well worked out how to use it." The opening bank heist, shot in Chicago in December 2006, went so well that the format was used in other sequences in the film.

"I felt it was very important that the first action set piece be shot that way as it is the introduction to the Joker," Nolan explains. "We released that sequence in IMAX theaters six months before the film came out just to give people a taste of what we were trying to do. I wanted to shoot as much of the main of the film in IMAX as I could. I love the idea of creating cinema on the grandest possible scale."

Of course, IMAX cameras are much larger and heavier, "But we wanted to treat them as if we were filming with regular Panavision cameras. We didn't want it to restrict us," says Nathan Crowley. That meant commissioning larger mounts so the IMAX cameras could be attached to cranes and vehicles.

From a design standpoint, Crowley had to adjust for IMAX's magnified scope. "With a 35mm camera, you don't see that much floor and ceiling, and you rarely see both at the same time. But in 70mm, the detail is immense. I had to be very careful about details. You can't have a bad paint finish. You need to make stuff look perfect, and that's a lot more work."

The filmmakers are betting that work will pay off, and reach beyond the genre audience. "My hope is that people will come away saying, 'That was a great movie,' not 'That was a great comic book movie,'" differentiates story writer Goyer, who admits to thinking about a possible Part 3, but like his colleagues, deems it too early to discuss. "I think comic book fans will embrace it, but I'm hoping that it reaches a little further."

It will have to in order to recoup an estimated $150 million cost, but "The Dark Knight" is expected to open at No. 1 and could take in close to $100 million in its first weekend.

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