School's out, but here's a pop movie quiz. What's the common denominator between Braveheart's surging armies, Die Hard 3's pulsing subway-signal lights, Apollo 13's smoke-belching rockets, Batman Forever's glistening Gotham streets, Judge Dredd's airborne motorcyclists, and many of Waterworld's seascape settings? Though you'd never guess it from the pristine images on screen, none of these wondrous sights is remotely real. They've all been grafted, animated, simulated, computer-generated, duped, and composited into existence in short, faked using state-of-the-art digital special effects. We don't mean to burst Hollywood's virtual bubble, but this summer, filmmakers are out to prove that the computer is much quicker than the eye. And it's not just the big, patently unreal sci-fi-and-fantasy pictures that are trying to fool the public. In everything from action flicks to family fare to melodramas, an astonishing percentage of the shots you'll see in the coming months were not simply captured on film but spliced, diced, and ''rendered,'' one pricey pixel at a time, by numbers-crunching software run on high-tech computer workstations.
''We're at the point where almost every major studio picture has a budget for computer enhancements,'' says director Chuck Russell, who used computers to turn Jim Carrey into a shape-shifting cartoon in The Mask last summer and may soon team with Arnold Schwarzenegger for the F/X romp The Eraser. ''The way the technology is going,'' declares Russell, ''doctoring moving images will soon be no more unusual than airbrushing a publicity photograph. What's scary is it's becoming just as subtle.''
And just as undetectable. Check out these seamless sleights of hand in several current and coming confections:
In filming Die Hard With a Vengeance, director John McTiernan found that stunt drivers careening down real Manhattan avenues couldn't always swerve as near to oncoming traffic as he wanted. So in postproduction, the cars were digitally hauled a few feet closer together, and voilà instant semi-fender-benders. And in order to allow Bruce Willis' truck-rig turnaround to escape a wall of water, thick cables pulling the vehicle were erased and the gravel disturbed by the rigging smoothed over.
Computer ingenuity even went into what may be Die Hard's smallest-scale, most stunt-free scene the one in which the film's villain forces John McClane to walk down 137th Street in New York's Harlem wearing a placard that says ''I Hate Niggers.'' One sign used during the filming had no words; in postproduction a computer added the new, offensive message. ''It would have been too risky to use the phrase we ultimately wanted in a shoot on a real Harlem street,'' says Diane Pearlman of Mass.Illusion, one of the film's several effects producers. ''Seen out of context, it could have caused a lot of trouble.''
While editing Braveheart, director Mel Gibson decided that in one major battle sequence, he and his posse entered a shot a little too soon. So the kilted one and company were digitally eliminated and their entrance delayed several seconds for dramatic effect. And what about those impressive masses of troops and battlefield corpses? Let's just say Gibson didn't exactly have to run a command the size of General Patton's. A pool of 2,000 extras was replicated to look like hordes in certain scenes up to 10,000 people. Don't worry about Mel injuring the horses, either: That lance protruding bloodily from one steed's belly was actually just a computer-animated prop.