JM: Call of Duty was obviously a touchstone, but we talked a lot about the Mac OS, where each iteration gets simpler. He's in essence surrounded by a 360-degree view of the battlefield. It's all virtual, but he's surrounded by it. And where he turns, the graphics follow his eyeline and we wanted to convey the basic amount of information you needed to know to play the game and play it well. We strived for simplicity.

BD: And what were the directors like to work with?

JM: Mark and Brian staged everything like a documentary and then went around on roller skates or hand-held to shoot whatever. So gathering data or even trying to figure out what they want to do in post, was a challenge. It's not like things are planned. In pre-production, I hired Halon to do previs, so we could understand the action sequences. And they spent around 10 weeks in Albuquerque doing what they do really well, and the directors looked at it three times and said great and then went off to shoot whatever they wanted to shoot. They don't work that way: they don't storyboard, they don't previs. They show up that day, choreograph the action and then figure it out. And from a vfx perspective, that's a very difficult way to work. More than any director I've worked with, they really like it to look invisible. We didn't even plan to put a helicopter in those shots -- it was something that was never discussed in prep. They never asked for it but we thought it would be really cool to do so and the only reason that the helicopters are still in the movie is because they look real.

BD: So let's get into some of this other CG mayhem.

JM: There are racer rounds, explosions, missiles flying, lots of CG helicopters; in fact, pretty much all of the vehicles you see are CG, with the exception of a stunt with snow plows. Those were done by Furious FX. All CG blood was simulated using Next Limit's RealFlow, creating defined shapes of flying liquid rather than just a particulate spray. After simulating, the liquids were rendered using Chaos Group's V-Ray renderer, which provided the opportunity to simulate accurate sub-surface effects and reflections. The finals were then output as multi-layered Open EXR files in unclamped float using The Foundry's Nuke, which gave Celluloid complete flexibility to create the final look of the blood.

The directors thought it would be really cool if they were walking on the moon, so Duboi built an elaborate lunar landscape.

BD: What about environments?

JM: There are different kinds of environments: there are obviously extensions to the Albuquerque skyline and it's a very low, kind of empty-looking city, so we tried to make it look a bit more metropolitan. There also a sequence in the picture when Michael C. Hall, the bad guy, and Gerard walk through a lunar landscape, just for no reason. If you've seen the Crank movies, Mark and Brian like to throw caution to the wind and do whatever jumps to mind. So there was this scene where they were walking through the desert and they thought it would be cool to make it look like the moon and you can see the Earth floating in the distance above them, so a company called Duboi in Paris built this pretty elaborate lunar landscape in the picture. It was just great eye candy.

So it ran the gamut of stuff that needed to look real and some fantasy ideas. That's the fun thing about working with these guys. They just have crazy ideas. At one point there was going to be a weird fantasy moment in the movie where Michael C. Hall rides a bike and they wanted to have the witch from The Wizard of Oz fly in the background. It got cut from the movie but that's the kind of idea that came while standing on the set with Michael C. Hall against a bluescreen.

Bill Desowitz is senior editor of AWN & VFXWorld.