Among action helmers, “The Hurt Locker’s” Kathryn Bigelow is something of a throwback — despite the current vogue for Paul Greengrass-style whip-pans and disorienting editing, the director tends to map her scenes as scrupulously as a military commander, keeping precise tabs on each character at all points during an operation. In no sequence is her spacial specificity more hair-raising than an early scene in which her trio of soldiers are called out to investigate a car bomb outside of an embassy. By-the-book Sgt. Sanborn (Anthony Mackie) is stationed on the roof, watching through his rifle scope as unfriendly faces gather on balconies and minarets; greenhorn Owen (Brian Geraghty) is down below, sitting tight in what he surely realizes is within the kill zone of the bomb; and live-wire William (Jeremy Renner) is inside the car, searching for the detonator with agonizing deliberateness (and recklessness). As Bigelow crosscuts between the three for 13 real-time minutes, the ratcheting tension becomes so unbearable, and the sense of impending violence so inevitable, that the scene’s explosion-free whimper of an ending registers as the biggest jolt of all.