Nevertheless, Lucas wanted the dewbacks, and the stormtroopers who rode them, to be in those shots. Berton and his technical directors had to figure a way to put the same filter over the new CG elements. But since the filter wasn't listed in the original camera notes, Berton's team had trouble determining exactly which Pro-Star was used. "One of the famous moments of the show occurred when we had George in to look at our footage," Berton relates with a grin. "We said, "we're really concerned about trying to match these computer graphics dewbacks into the existing footage because we're seeing all of these star-cross filters everywhere, and we're looking at how to emulate something like a Pro-Star in an image processing format.' And George said, "Well, you know, we just put nylon stockings over the lens in order to give the desert some diffusion that would really make the stormtroopers look good!' People don't put nylon stockings over their lenses these days, but back then it was a common practice. Computer graphics, needless to say, were not common. But somehow we had to meld those technologies together. We eventually wrote image-processing programs that basically spread out the high-end light in a way similar to how a nylon net would do it; we then added little rings of color to give the spectral range."
Compared to the photographic issues, the modeling and animation of the dewbacks and other CG characters followed the standard evolution of digital effects: the models were first constructed as wireframe armatures in Alias, then animated, and finally textured and rendered in Renderman. In spite of their white plastic armor, the CG stormtroopers riding the CG dewbacks presented problems unique to the human form. "There's a reason we started out with liquid-metal men and dinosaurs as we began making great strides in effects at ILM," Berton says. "People are tough [to animate] because we know what they look like. And the closer you get to something familiar, the more precise you have to be in your thinking to make them move. Real human beings are much harder because they have facial features and hair, which we were glad to dispense with. But finding a way to reproduce realistic movements became a really big issue with regard to the stormtroopers. They were relatively easy to assemble because computer graphics mimic plastic rather well, and we also had all of the reference footage we needed to build the models. But eventually, it came down to real motion. The stormtroopers still move like human beings because they're guys in armor suits, so to take a CG stormtrooper and put him right next to a guy in a suit in the same shot, and make it work, was no small task."
That Star Wars takes place in a retrofitted future led to further complications. "Everything was dusty, everything was dented, and this understanding of everyday wear and tear gave realism to the images," Berton opines. "But we had to deal with that too. So just when you think, 'Oh good, stormtroopers—white plastic with black,'—George has done us the favor of making it difficult again because of all the dirt and mud. So we used the same techniques for painting textures onto dinosaurs to paint dirt onto the stormtroopers. Some of it was painted on by hand and some of it was done with computer graphics procedural techniques—adding dirt into the perimeters which created the renders, like noise fields."
In one of the most startling shots set in the rolling dunes of Tatooine, a stormtrooper rides a dewback across frame in close-up. For a shot in the Mos Eisley spaceport, a stormtrooper dismounts a dewback in the background behind C-3PO and R2-D2. These disparate shots illustrate the problems involved in creating realistic human animation. Berton explains, "In the first shot, the rider's motion was a little more repetitive. But when the focus is on something that's not moving that radically or going through such an obvious motion as dismounting, we had to pay more attention to the nuances, because anything can give away an animation cycle. I think the dismount was the best job we did on the stormtroopers. The dismounting trooper was in a scene in downtown Mos Eisley. It involved a very difficult camera move which we had no record of, and the lighting conditions were changeable and more complicated than in the dunes. Although dismounting is a very clear action, and we had lots of reference of people getting off horses and climbing down from elephants, we still worked very hard to make that shot work."
While the dewbacks are associated with the Empire's military campaigns, two other native Tattooine creatures are seen roaming the streets of Mos Eisley: the brontosaur-like "rontos" (the Jawas' beasts of burden), and the diminutive, feral "scurriers." Berton explains, "We were trying to build some creatures into the city that would really give it some scale and some mass."
A potent combination of dewbacks, rontos, scurriers and many ILM employees, family members and friends—shot against bluescreen and disguised as stormtroopers, aliens and desert dwellers—successfully transformed the once-sleepy spaceport into the fabled "hive of scum and villainy" that erstwhile Jedi Knight Obi-Wan Kenobi described it to be. But ILM didn't simply make Mos Eisley seedier; the spaceport was also enlarged, thanks to the efforts of digital matte department virtuosos Yusei Uesugi and Paul Huston.
During his career, Uesugi has made the lightspeed jump from traditional painted-glass backgrounds to computer technology. He used various 3-D modeling programs to build Mos Eisley in CG, creating beautiful backgrounds for effect shots that parallax flawlessly with camera movements. "The shot were Luke's landspeeder comes into Mos Eisley involves a crane shot that starts on two robots fighting. We then move up as the speeder goes into the city, and we see rontos and hundreds of people, mountains in the background, and spaceships flying around," Berton marvels. "That's a totally synthetic shot, and that's the wave of the future in terms of what I call Digital Cinema."
Conversely, Huston, who built models for the original Star Wars, used his expertise to construct a miniature Mos Eisley set from foam-core, paint cans and plastic balls; he physically painted and aged the materials before squeezing off pictures of the model on his 35mm still camera. Huston then scanned the stills into the computer and used them as the basis for his matte painting of the spaceport.
Working in collaboration with visual effects supervisor John Knoll (Star Trek: First Contact), Huston also constructed a 6 foot-wide foam-core model of Docking Bay 94. This setting was enhanced with a new high-angle shot that peers down into the bay as Han Solo's freighter, the Millennium Falcon, blasts off into Tatooine's upper atmosphere. Huston photographed the interior of the docking bay outside, at a predetermined time, to get the precise angle of necessary sunlight. He then painted his matte over that shot in the computer. Knoll subsequently projected Huston's 2D painting onto some rough 3-D geometry he modeled in the computer, which enabled him to do a virtual pan-tilt across Bay 94, replete with the lens distortion of a real pan and tilt on a real set. "That way, my shot could have the proper lighting interaction," Knoll says. "The CG Falcon could emerge into the sunlight streaming into the bay, and cast shadows onto its walls." Knoll's main inspiration for the spacecraft's motion was a shot that happens later in the film—as the Falcon escapes from the Death Star, it pulls out and turns around before soaring into empty space.
The following shot, which depicts some stormtroopers in a Mos Eisley alleyway watching the Falcon blast off, was on Lucas' wish list from the outset. "In the original, the Falcon was probably a cutout photograph just going up at this diagonal," Knoll speculates, "and the lighting didn't really match the shot's sunset look. Now the lighting's perfect. I also had the Falcon travel a lot faster on a curved path, so you actually see its perspective change as it gets smaller."
[ continued on page 4 ]