Hollywood's Secrets Revealed: Special Effects in the Movies (page 2)

Developed for film as another method of compositing, the blue-screen process quickly became the most popular technique for creating unusual backgrounds. First, the actors are filmed against a blue screen. Then, with a little darkroom wizardry, the blue areas were replaced with a background screen, dropping the actors into any world the producers desired.

The same process soon applied to video and computers. With film the process is chemical, with video it is electronic and with computers it is algorithmic. Of the three realms, the algorithmic is the most flexible.

There are some problems with blue-screen. If the talent wears something blue it will become transparent, poking a hole right through the actor. You need to be very careful with the wardrobe for a blue-screen shot. This caused some consternation on the set of the movie Superman, where the blue-suited hero had a tendency to disappear altogether. To fix this niggling detail, they made a special purple Superman suit. Before compositing the final image, the suit was color-corrected back to blue.

In the good old days of black and white movies, blood (when shown at all) was just chocolate syrup. The actor put a little syrup in his hand and slapped it onto his chest for the easiest gunshot effect of all time. In the age of super-realism, that technique just won't cut it. You need "Technicolor Blood" (that's the actual trade name). It looks great, it scabs over like the real thing and, it's washable.

Blood often involves plumbing. A gushing wound requires tubing to deliver the blood. Technicians often hide the tubing behind latex appliances (porous foam rubber made to look like skin), but it is simpler to have it run behind something, out of the view of the camera. Another way is to attach the plumbing to a knife, ax or scissors. Add a tube to the unseen side of the murderous instrument and have it deliver blood as it slices, chops or stabs. A rubber bulb at the end of the tube is us>Blood often involves explosives. To simulate a gun shot with maximum grossness, technicians use a squib, which is a small electronically triggered explosive. To simulate a gunshot wound to the chest, they strap a metal plate to the actor's chest to absorb the impact of the squib. The squib is attached to a small rubber bag of fake blood. The actor dons his costume, and on cue, the technician explodes the squib and blood splats all over.

Videographers have borrowed effects like these from Hollywood for years. These are just a few of the tricks the masters use to fool the audience. Throughout movie history, directors have pushed the limits, constantly gaining an advantage over their peers. The effects are now so good that they are virtually undetectable. What will come next from the fevered brains of the F/X wizards is anyone's guess, but you can bet that videographers will be performing the same effects in their backyards in the not-so-distant future.

With Jurassic Park, the world of special effects changed forever. No longer content with bit parts and touch-up work, computers burst on the scene with full-blooded, snorting, sneezing dinosaurs.

How do you build a digital dino? First, using fossils for accuracy, the graphics gurus created a computerized skeleton. Then, advised by paleontologists, they programmed the muscles and wrapped digitized skin around the carcass. Finally, they computed the motion.

At that point, hundreds of networked computers went to work, calculating how the light would reflect off the dinosaurs and back at the viewer. The calculations are so complex, it could take hours for a workstation to generate a single image.

Finally, after thousands of frames had been generated, the dinosaurs were composited with the live action. The result is a stunning realism that immediately became the gold standard for effects. Although the traditional methods discussed in this article are still used, their days may be numbered---in Hollywood.

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