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SAN RAFAEL, Calif. - Jar Jar, racing space pods and Darth Maul's light sabers, as well as The Mummy, are arising not from outer space or the Egyptian desert, but from a nondescript industrial park. While George Lucas and his animators have people camping out for seats at the Star Wars "prequel" opening this week, it's the inventors at Industrial Light & Magic who really make that film; and others loaded with special effects; happen.

Engineers at ILM, the technology arm of the Lucas empire, have been creating and fine-tuning everything from cameras to disk arrays to controllers and networks for roughly two decades, all in an attempt to make the real and virtual worlds mesh so well that moviegoers can't tell where one ends and the other begins.

"We always have to invent new things, though often we're building them with off-the-shelf components we put together in ways the companies never thought of," said Gary Meyer, chief engineer for video engineering. "The way ILM works is that everything is in a constant state of evolution. As new shows come on, we try to do things faster and more efficiently as technology evolves."

Marty Brenneis has been inventing and reinventing film-industry technology for years. He was the first electrical engineer ILM hired, back in 1979. Described by coworkers as a wizard, he's created all kinds of cameras and camera carriers that have made it possible for Luke Skywalker and other celluloid heroes to race pods through worlds that don't exist.

Brenneis came up with the idea of a camera that moves down an 80-foot track so precisely that it can film several different takes, which can be combined to create the illusion of vehicles or monsters hurtling through space. Moving the camera instead of its target makes it possible for filmmakers to turn on lights during one sequence and engine flame during another, add an explosion in a third and then blend them all to get an image with far more details than a single pass could provide. Exactness is an obvious must, or else hours of costly processing time will be spent correcting the combined multiple images.

"This has to be dead-nuts-on accurate, or you won't buy it when you see the movie," said Brenneis, who works out of ILM's camera-engineering department. "That's why I use stepper motors to control the crane that takes the camera down its track. Steppers are either dead on the mark or they're broken. If a servo controller dies, it can tear your arm off. They keep telling me these cameras are going to be obsolete because everything's going digital, but we have four of them running simultaneously now. The newest is called the Mooseflex, because it used to make groaning noises that sounded like a moose. I went in and tweaked the steppers to make it quieter, but the name stuck."

The cameras Brenneis designs are so unique that when they break, he's the man who's called to fix them. And given the costs of shooting major productions, those fixes have to be done quickly, regardless of where the cameras are when they fail.

"During [the filming of] Dragonheart, a camera broke in Slovakia and they wanted me on the plane in four hours," Brenneis said. "It took 23 hours to get to Slovakia, and once I checked the camera, it needed parts. The technicians there told me I'd have to send a fax and get the parts overnight from the United States. I went for a walk in the city and found a very well-appointed electronic-parts store that had everything I needed."

Another time, he said, "I had to replace a power FET on a camera that was on top of a building in Chicago. Six hours and 15 minutes after I got the call, the camera was fixed."

Meyer and Brenneis are a couple of the 1,200 employees at Industrial Light & Magic. While director/producer Lucas and others work in a spacious, stylish ranch in the hills, these engineers labor in a site surrounded by auto-repair shops and some small assembly shops. That's not to say the sprawling, 25-building campus - hidden without so much as a front-door nameplate - is drab behind the scenes. Engineers often bump into the likes of Clint Eastwood, and they sometimes watch the daily shots in a plush, state-of-the-art theater. Their challenge is the constant struggle to come up with technologies that meet the needs of Lucas and others.

"We're continually inventing new black boxes; we find that often the off-the-shelf products don't perform at the speeds we need," said Meyer. "We build controllers that link the various boxes together. We'll buy things like a disk array, frame buffer and some other off-the-shelf products and build them into a usable system. Some are simple and some are very complex."

Among the simple ones is a 386 box that has run Linux without a glitch for nearly five years. Called Robot, it handles routing commands so that one of the systems can be accessed from any terminal in the system. Another "cheap PC with Linux on it" houses a TTL data-acquisition card that saves Meyer and his cohorts plenty of time when systems have to reboot.

"We call it Kicker. It pulls the TTL lines low and reboots the system," Meyer said. Other, similar devices "drop power to reboot," but Kicker does not. "If you completely drop power on a big file server, powering it down and resetting it can take 10 minutes," Meyer said.

Far more complex is a system that lets producers, photographers, artists and others view the same screens in real-time wherever they are. When the dailies are compiled after every day's shooting, various people need to communicate their views of how the shots turned out. Often, the shots are created in the camera sets at ILM and merged with other digital images.

When one director had to be in New York during a critical period of shooting elsewhere, Meyer was called in to create a videoconferencing system that could carry both the movie and images of people at both ends of the connection. Data originally went over fiber but was recently switched to satellite links.

"Our system is like a videoconferencing system, but it has high resolution; 30 frames per second," Meyer said. "We've also got a cursor overlay so when one side moves the cursor, the other can see it move to the same point. We use a 45-Mbit/s pipeline."

Two shots, one day

The bottom line is to shorten the amount of time needed to process daily shoots. Previously, film or videotape would have been shot, and combinations of special effects or virtual characters would have been added. Then the video would have been sent from ILM to the director, often in Hollywood. "It took almost two days to take a shot and make a change," Meyer said. "Now we can make two shots with changes in one day."

Meyer noted that designing hardware for artists is a far cry from his earlier experience in the aerospace industry. "It definitely adds a level of difficulty," he said. "We have to design the system so it's easy for the artist to use. The user interface has to be very intuitive, clear and graphically pleasing.

"I'd probably design the system significantly differently if bankers were accessing it."