Steve Daly breaks down a single shot from ''M:I-3''

Summer movie season is here, even if summer itself isn’t. That means it’s time for another slew of spectacular, super-tricky effects shots on the big screen — and time to deconstruct some of the best.

THE MOVIE Mission: Impossible III

THE MOMENT Super-agent Ethan Hunt (Tom Cruise), after being tortured by super-baddie Owen Davian (Philip Seymour Hoffman), busts out of a small Shanghai building onto its tiled rooftop. (This is about 90 to 95 minutes into the 126-minute movie.) He gets his bearings as the camera swoops around him — he’s overlooking a canal — then he jumps down multiple roofs and onto a small canal bridge. The series of jumps happen all in one sustained, unbroken camera move, as Ethan gets frantic directions on his cell phone from another agent who guides his escape run by tracking his signal on some kind of satellite map.

WHY IT ROCKS In a movie loaded with good but detectable CG effects — a hi-tech rubbery mask that form-fits itself to Cruise’s face, an assault on the Vatican’s walls, a bridge attack meant to be in Virginia’s Chesapeake Bay but filmed largely in Simi Valley — this shot stands out for looking utterly real. That’s because, by and large, it was, according to visual effects supervisor Roger Guyett (a veteran hand at George Lucas’ Industrial Light & Magic shop, who worked on Saving Private Ryan and Casper, among other gigs). Cruise was not CG’d into the image via bluescreen or greenscreen or any other kind of screen — he’s really jumping along tiled roofs and down onto a physical, actual bridge — and he’s not wearing any harness or stunt wires. The camera seems to literally fly around him, like a free-floating hummingbird.

HOW THEY DID IT There’s a dash of CG trickery involved, but not where you’d expect. Most of the ”effects” are practical things done on the set for real. First, the filmmakers built their own faux-rooftop set over existing buildings in Xi Tang, a neighborhood about 100 miles west of Shanghai. (Cruise would have liked to clamber over real buildings, but their traditionally constructed tile roofs would never hold the weight of a crew — or even a Cruise.) Then three tall metal towers were built around the set to support a type of camera rig called a ”spider-cam.” It’s similar to a system called ”Skycam,” which was pioneered as a tool for covering pro football games — initally for the ill-fated XFL, then for NFL coverage on ESPN and ABC, as well as for a variety of other sports. Cables were run between the towers like a cat’s cradle, and connected to a camera on a sort of airborne sled. (Picture the droid probe from the start of The Empire Strikes Back — except on wires, not free-floating.) By adjusting the wires’ lengths via remote controls, the crew could make the camera fly in and around any position — which it did, as Cruise made that maniacal series of leaps down onto the canal bridge. CG was then used in post-production to ”paint out” the towers and the camera guide wires, and to enhance the distant skyline to make it look more like central Shanghai. ”Say what you want about him,” says Guyett of Cruise — a reference to the star’s controversial pronouncements of late, what with all the couch-jumping and amateur sonogram action. ”But he’s got some serious balls to do a lot of these things. You wouldn’t want to fall in that river…[and] he did it without a harness.”