The fine art of making a room go boom

HOW do you light a man on fire, blow seven others to bits, choreograph a gun battle with 20 shooters, discharge 400 special-effects squibs, shatter a panoramic hotel window, separate an FBI agent’s torso from his waist, then show a neo-Nazi to his seat -- which happens to be a chain saw -- all in mere minutes?

The secret lies with writer-director Joe Carnahan and the team of specialists he brought in to handle the wet works in his new movie, “Smokin’ Aces,” opening Jan. 26.

Carnahan calls the final sequence “Doomsday on the Penthouse Level,” in which he tempts a ruthless cast of assassins and law enforcement officers to the top floor lobby of a casino hotel then pulls the pin.

“I wanted to make something so wild,” Carnahan says. “And I like tons of stuff going off at the same time, all in the same frame.”

Imagine a deus ex machina moment in which God is reincarnated as the most hyped-up film fan in the universe. As if 50 times over he’s studied the high-octane ending of “Mad Max 2: The Road Warrior,” the gunfight at the end of “Bring Me the Head of Alfredo Garcia,” the helicopter invasion in “Apocalypse Now.”

Carnahan’s angels of death on this mission were cinematographer Mauro Fiore (“Training Day”), production designer Martin Whist (“The Island”), stunt coordinator and second unit director Ben Bray (“I {heart} Huckabees”), and special-effects coordinator Larz Anderson (“Hostage”).

Reading the sequence for the first time was like a fantasy come true for Bray. “I heard beautiful music in my head,” he says. “Every [stunt] coordinator’s dream is a sequence with weapons, a number of people, blood, fire, debris.”

With his A-team signed on, Carnahan set up the “Smokin’ Aces” production offices and posted the storyboards for the elaborate lobby sequence.

“It was almost like osmosis,” Carnahan says. “You had to walk right past those boards. That way people had a working knowledge of what we were doing. As you walk past, it’s like, ‘Oh, yeah! That guy’s got to sit on a chain saw. How we gonna do that?’ ”

First, they had to conceive of a space for the combat to unfold. Carnahan asked tactical weapons consultant Paul Maresse to identify a worst-case scenario. He described a situation with little room to maneuver amid a barrage of crossfire.

With that in mind, Whist designed a lobby set to accentuate the feeling of being pinned down. Characters unload on each other while clinging only to hallway walls. An M-50 is fired into the set through a large window directly across from two elevators that successively offload assassins and law enforcement into the melee. Given the 360 degrees of action, Fiore had to figure out a way to intelligibly light and cover the helter-skelter panorama.

“We came up with a specific lighting design with a fixture hanging in the center of the room so we could light all the characters and keep the light off the walls,” Fiore says.

The whole sequence is shot as if seen through the eyes of the Tremor Bros. characters, three neo-Nazi psychopathic assassins, who Carnahan claims are huge action-movie fans. As a result, Carnahan and Fiore wanted to make the scene feel like the Tremors’ deranged yet lucid dream. To achieve this, they over-cranked the cameras, shooting the scene at 120 frames per second, which to the eye appears to slow down the motion five times from the normal 24 frames.

“Visually it’s beautiful, it has such great attitude,” Carnahan says. “But it’s really tough to coordinate when you’re looking at 120 fps; you open yourself to scrutiny ad infinitum. People say, ‘Aw, that didn’t hit there.’ ”

The only way to avoid such criticisms was to time shots perfectly. Bray’s stuntmen and crew ran through the blocking six times, videotaping it once for dissection, over five rehearsal days. When they were ready to roll film, Fiore set up a dolly track so he could capture the action sequentially.

“We thought it would be more interesting to see things move through the frame than us moving to capture everything,” he explains.

Every department had a safety zone. Fire extinguishers were nearby. Anyone on the frontline near the camera was issued a pair of goggles and a shield, Bray says.

Such measures helped prepare the crew for one of the most difficult shots in terms of both timing and safety. It’s a gag known in the stunt world as a “full firebird.”

All set, open fire

PERFORMED by Frank Torres, a veteran stuntman and Bray’s assistant coordinator, Torres runs through the frame fully ablaze while firing a 9-millimeter. Along the way he takes four squib hits then burns on the ground for four seconds.

“What I love about Joe is he does long shots,” Bray says. “There’s no break in the action, so we get to see his burn long and drawn-out.”

Slightly less lyrical is a shot in which an FBI agent is bisected across the stomach with a Tremor Bros. chain saw. Stuntman Frank Lloyd sells the moment with facial expressions and body spasms. An air pump with a funnel tube spews blood and chunks of gore into the frame for good measure.

Throw in a few hundred spent squibs, fake blood, shards of glass, smoke, water from an overhead sprinkler system, balsa wood detritus from special-effects explosions, and you’ve got one heck of a sloppy set.

“The walls were torn up, the elevators were bent and the floor was soaking wet with water and blood,” Bray says. “When we were halfway through filming, visitors asked why we were already breaking down the set.”

Carnahan says going into such demolition mode for the scene comes down to wanting to bring his own brand of action to “Smokin’ Aces.”

“We didn’t want to do the lame dives as the explosions go off in the background,” Carnahan says. “We went as deep as you can get with a sequence like that. We broke it down to almost a binary code then infused it with its own kind of beauty.”