Welcome to a look Inside the Holocron. A collection of articles from the archives of *starwars.com no longer directly available.
(*Archived here with Permission)
Let There Be Light!
As one of the three Industrial Light & Magic visual effects supervisors who worked on Episode I, Scott Squires had to deal with the creation of virtual realities on a daily basis. But the challenges of visual effects have changed a lot since the computer revolution reached cruising speed at the beginning of the 1990’s.
Now able to manipulate photons like atoms to create an entire universe and its inhabitants, the visual effects wizards at Industrial Light & Magic use computers to accomplish an always-increasing number of tasks that were traditionally handled not only by model builders, but also set builders and practical effects specialists.
“Our first step is to scan the film into the computer so that the whole shot is digitized,” says Squires. “Then everything is done digitally from that point.” For visual effects veterans, this is a great leap from the way effects work was accomplished before computers took over. For instance, the traditional procedure used to combine several different elements in the same frame is called “optical compositing,” and involves the projection of a series of already-shot visual elements that are re-photographed, in sequence, on unexposed areas of a previously partially-exposed strip of film. Optical technicians first photograph a background using mattes, which are opaque silhouettes used to block out certain areas of the film. Then the technicians “fill in the gaps” by photographing the rest of the elements, placing each of them in the proper blank space left by the mattes during the first step of photography. But if the asteroid added to the star field background during step two needs to be partially covered by a spacecraft, then the asteroid will be photographed with a matte in the shape of the spacecraft on top of it, in order to leave the blank space that will be occupied by the ship in step three – and so on. When this delicate process is completed, when all the layers have been added, the result is one frame of film. Twenty-three more of these will be required to create the illusion of one second of movement on the screen.
Visual effects used to be created in such ways, because optical compositing was simply the most effective process at the time. All the space battles in the classic Star Wars Trilogy, among other scenes, were painstakingly done using optical compositing techniques. In some cases, particularly in Return of the Jedi, the procedure involved putting together up to forty layers of visual elements combined on a background, for just one frame of film. Now that the digital revolution is in full bloom, the technology allows visual effects creators to combine different elements within the memory of a computer, without ever touching a piece of film. And though the digital age gives filmmakers access to a broader range of effects than what had been possible before, the work remains just as complex as it has always been. Better doesn’t necessarily mean easier, especially in the world of visual effects.
Whether the computer is used to combine two live-action elements photographed separately or a live-action shot with a computer-generated object, the process of digital compositing remains generally the same as it was with optical compositing, with each new layer being added onto the previous ones. Except, of course, that everything is accomplished within the computer. More importantly, the output also remains the same: one frame at a time. “After the digital work it goes back out of the computer: we put out little frames every day – this is called a “wedge” – just so we can check the color and the look on film,” says Squires. Still, today’s visual effects wizards have more power, and can do more in less time than was required in the past. Gone are the days of white-gloved optical artists manipulating strips of film in a dust-free environment. But enhanced power comes with enhanced challenges.
“I guess the biggest challenge was the volume of complex shots,” Squires says. “Our team alone had to deal with 561 shots in less than a year.” Dennis Muren and John Knoll were handed out different volumes of shots, based on the complexity of the work involved. So Muren’s team had to produce 310 shots, while Knoll’s team tackled an impressive 1072 shots. In Muren’s case, the number of shots was kept at a minimum because he needed to produce scenes that were completely computer-generated: the underwater sequence and the ground battle. And since an outside, daylight scene is the most difficult environment to create digitally, the ground battle alone represented quite a challenge.
“For my team, this meant twelve to fifteen final shots each week,” continues Squires, “compared to the average output of about 5 VFX shots a week on a major motion picture. And we needed to keep the quality level up, of course. So part of the challenge on this movie was to find creative and clever solutions to problems. To speed up things, we needed to find a balance between digital and practical effects. So for certain sequences, we would shoot physical models, and then digitally enhance the footage. At other times, we might use a digital matte painting instead of having the computer render a new background for each frame. And so on. We even used salt, poured from fourteen feet up in the air, as the basic visual element for the Theed waterfalls.”
However, as Squires points out, digital technology has reached a point where another type of challenge arises: “We also need to know when to say, okay, let’s stop here,” he continues. “One of the great things about this technology is that you can control everything to the Nth degree, but a lot of times you have to take a step back and realize that the element you’re working on might end up onscreen for two seconds. And sometimes, it won’t matter whether a particular piece of hair goes this way or that way. You just have to look at it realistically and make sure that your last few months on the project are spent finishing the film, and not making half the movie more perfect than it needs to be. Basically, we bring each shot up to the level George Lucas wants and needs. Then it’s time to move on the next shot.”
As traditional visual effects artists have discovered long ago, it is not always wise to do everything to make an effect absolutely perfect simply because the technology allows its users to do so. Most of the time, an element doesn’t need to be perfect in real life to look perfect on the screen. It’s a question of balance, and in that, digital technology hasn’t lightened the burden. It may in fact have made it a bit heavier. But the wizards of ILM rose to meet the new challenges of visual effects, and stand ready to repeat the feat on Episode II. The ‘magic’ in Industrial Light & Magic doesn’t only appear in the final product on the screen : It is part of the whole process.