Exterior Stateville Prison. The left side of the prison contained a modern "sally port" (entrance), which was bluescreened, and replaced with a matte painting by Illusion Arts. All images copyright Universal Pictures.

Public Enemies is summer counter-programming at its best: a prestigious biopic about gangster John Dillinger starring Johnny Depp and directed by Michael Mann, with definite Oscar potential. Not a lot of flashy CG, but noteworthy vfx nonetheless. VFX Supervisor Robert Stadd discusses the challenges of doing period work and collaborating with Mann in this VFXWorld exclusive.

Bill Desowitz: It's really hard to pull off period gangster isn't it?

Robert Stadd: I think Michael had a good take on all that.

BD: Sure: Dillinger as the last of the outlaw gangsters made obsolete by technology and social engineering. And who would've guessed 400 vfx shots? You did a terrific job of hiding them.

RS: I've worked with Michael before -- this is my fourth film with him -- and the thing is he gave me very little direction during filming, because I know. What he wants is it to be invisible, seamless and not to slow down the story. Nobody should ever know it's a visual effects shot.

BD: That's pretty much the mandate for everything unless you're doing fantasy, sci-fi. And even the comic book movies want to be more naturalistic.

RS: They do but they're not always successful. I have to say that I spot them most of the time. It makes you crazy. But we should never for a second think there's anything out of the ordinary. And that just goes back to old school, traditional lighting, matching, lenses, all that hard stuff. That's basically it. And I use everything in the book, from CG to split screen to bluescreen, greenscreen. And really I looked at this as anything it took to get the job done. There was some CG, certainly, when Dillinger gets killed in the end, all the blood is CG. There was no other way to do it. And also Michael shoots at a pace. I mean, we shoot fast, even though it's at a reasonable schedule.

BD: Maybe it's that early TV background.

RS: Who knows? I think what it is: he wants to stay in the dream, in the story. And when he's there, he wants to be looking while we're filming and get every bit of it. He never wants to slow down, he never wants to stop. And the other thing is, you have to be ready. You just have to read the signs and be ready. He's not going to say, "I want a bluescreen here and we're going to shoot from this angle." You just have to know. The first time we see them robbing a bank, there's a shot of Dillinger jumping over the transom, which required a face replacement. That came up like five minutes before. There's a lot of that going on.

BD: How much previs did you do?

RS: We prevised the very end when Dillinger gets shot -- and the way we shot it was completely different from the previs. And that was just one shot. Sometimes I try to do a lot of storyboards. On this one, I did just a couple to give him an idea of framing. Nine times out of 10, it's not what we end up doing. On the shot of Johnny jumping over, that was a case of the stuntman doing an amazing job -- he was like a gymnast pausing in mid-air. Johnny couldn't do that. Then we shot Johnny doing it mostly for lighting. Then afterward there was a scanning session for his head and also for the end. So we had some CG heads that we could use and we used them a lot in the bank robbery.

BD: Who worked on that shot?

RS: CafeFX. They also did some interim work on Dillinger's death, but, really all that blood stuff was Hammerhead. We built about 60% of it in CG with 3ds Max and then using Nuke we just manipulated it. And then Hammerhead shot a bunch of live-action elements of blood just pouring out of him (using a Styrofoam head).