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Star Wars Super Models

Star Wars Super Models
Film Relied on Innovative Modeling Techniques to Create the Digital Stars, Pods, Props, and Sets of Episode I: The Phantom menace
By Barbara Robertson
There`s at least one thing everyone who has seen Star Wars Episode I: The Phantom Menace can agree with: This movie is filled with digital visual effects. Indeed, most scenes include elements created at Industrial Light & Magic (San Rafael, CA) with computer graphics tools--elements as imposing as digital characters and space ships and as invisible as set extensions. When you stop to think that each little bit of computer graphics (with the exception of pure particles) had to be modeled, the sheer enormity of this effort can`t fail to impress. "We created models that ranged in size from as small as a mosquito to Fambaa [a huge animal], which is 30 feet tall," says Geoff Campbell, digital model supervisor.
The models fell into one of two categories, organic or hard surface, each having its own methodology and requirements. Organic models were used for principle characters such as Jar Jar, Watto, Sebulba, and Boss Nass; secondary characters such as Yoda (when he`s walking around), Jabba the Hutt, the two-headed pod-race announcer, pod-race drivers, several varieties of animals and "fish;" plus many background characters. Hard-surface models were used to create props that ranged in size and complexity from saddles and reins to energy balls. Hard-surface models were also used for droids, space ships, racing pods, the Gungan submarine, and for a few sets. While most exterior shots used miniatures, CG models were used to extend or create four interior sets: the Theed central hangar, the palace hallway, the generator room, and the galactic center rotunda. Approximately 18 modelers worked on the movie, according to Campbell. Some concentrated on one category, but many worked on both types.
Shaping Characters
All told, the movie included 66 characters and creatures, and for these organic models Campbell and his team used Softimage 3D, Alias Power Animator, and ILM`s proprietary I Sculpt software running on SGI workstations to create and shape the basic mesh. For models relatively close to the camera, the modelers created additional shapes that animators could use to enhance a character`s performance--to move its clothes, perhaps, or to help it breathe. "The Gungan guards had to stand at attention for 360 frames," says Campbell. "That`s really hard to animate, so to help the animators, we created breathing shapes." In addition, six of the characters talked and thus needed libraries of shapes for lip synch.
The process began early for Jar Jar Binks, the gangly, long-eared side-kick to Qui-Gon and Obi-Wan Kenobi. "George [Lucas] wanted Jar Jar built digitally to see facial expressions quickly," Campbell says. "So in 1996, Steve Applin and I roughed out a model and went to the Ranch [Lucasfilm headquarters] to work for two months." When Lucas was satisfied with Jar Jar, the character became the first to be fed into the ILM pipeline. Campbell continued working on the model, and it became the basis for the entire Gungan species. Applin moved on to Watto, the junk-dealer with an elephant nose and hummingbird wings, and Paul Giacoppo took on Sebulba, the nasty pod racer.
For each new character, the modelers worked with Tim McLaughlin, a technical director who considered the enveloping and simulation, James Tooley, who designed the constraints (the chains), Jean Bolte, a painter, and designer Doug Chiang. First, the group would decide how much detail a character would need.
"Some of the pod racers would go by so fast that we could build a low-res character that was almost a card, a projection onto a plane," Campbell says.
For high-res characters in the foreground, they would determine how the character needed to move, how much of it could be painted rather than sculpted, and whether the character needed facial expressions and lip synch. Once they started building the models, the animation group became involved, and together the teams began to define key poses for facial expressions and lip synch.
All the characters in the movie wore clothes--Watto and Sebulba had leather vests, Boss Nass and Yoda wore robes, Jar Jar tied a sweater around his waist, and the Gungans had a variety of costumes depending on whether they were soldiers, calvarymen, civilians, or principal characters. Some of the clothes were modeled separately to make it possible to animate them using simulation software. "Jar Jar`s pants and undergarments are part of his body mesh," explains Campbell. "But his sweater and vest are modeled on top." Similarly, Boss Nass`s robes are modeled separately for the simulator.
The clothes added complexity to the already complex models, according to Li-Hsien Wei, who worked on 20 models for the movie, including Captain Tarpals (a Gungan soldier), Sebulba`s face shapes and clothes, two additional pod racers, and several animals. "Sebulba is close to Draco in size," he notes, referring to the hefty, complex dragon model in the movie Dragonheart.
"Fortunately, the computers are getting faster, and our software is good for working with heavy models."
Wei created basic structures with Power Animator, reshaped volumes to do such things as lengthen arms and enlarge heads with I Sculpt, and manipulated CVs (control vertices) for the B-spline models using Softimage 3D. For example, to transform Jar Jar into a model for Captain Tarpals, Wei used I Sculpt to make global changes to the body; but for Sebulba`s facial expressions, he used Softimage 3D to create detail around the eyes. For the Eoopie, a four-legged llama-like creature with a snout, and the Kadoo, a kangaroo-like animal, Wei started by using I Sculpt to reshape 3D scans of maquettes.
Creature artist Alyson Markell, however, created the Dewback, a lumbering lizard-like creature, the Ikopi, a deer-like animal, and the head of Sando, a huge underwater creature, from scratch. "I`d get the basic proportion in Softimage or Alias, then would pretty much hand-sculpt the model from there using I Sculpt to add muscles, shapes, and skin folds." One character for which skin folds were especially important was Jabba the Hutt. "I started with Jar Jar`s model, then began deforming it by adding face shapes, breathing shapes, and muscles in his chest and stomach," she explains. Then she modified Jabba`s model to create his mother. "I use the same geometry so I can keep the same patch names and counts. As long as the numbers and names stay the same, I can deform it [with some restrictions]", she says. "If the model is going to be animated, I can make the new one wider or thicker, but not longer than the chain in the original."
The hard-surface models that most resemble character models are those for the droids. These models were chained with skeletons for animation as were the organic characters; however, the droid models, many of which would be animated with the help of motion-capture data, had particular characteristics that affected their movement. For example, they had pistons between their hips and chests. Also, "a motion-captured head might move from side to side," explains Paul Kavanagh, technical animator, "so we built restrictions into the droid model to prevent too much movement." And since many of the droids would be destroyed, they were designed to easily come apart. Thus, despite the fact that these "characters" could walk and talk, they were modeled using techniques that might have been used for other machines.
Hard Surfaces
"When you`re sculpting a creature, you`re pulling CVs to create the shapes," says Russell Paul, lead hard-surface modeler. "But when you`re creating a machine, you work with definite, abutting surfaces." Paul, who left Alias\|Wavefront`s Industrial Design group in Toronto to join ILM, used Alias\|Wavefront`s Studio running on SGI workstations for modeling the destroyer droids, the Gungan submarine, racing pods, the Naboo Starfighter, and the all-chrome queen`s ship. "In some cases, the process is different from industrial design because you are creating an illusion," he says. "You can paint holes, for example, and you don`t always have to model them." But because the queen`s ship was totally reflective, they couldn`t cheat with bump maps and paint. "We built the queen`s ship just like a car," he says.
In fact, ILM milled a seven-foot-long model from CG data and used that model in shots when the ship sat on the ground. For the space-battle sequences, models for the Starfighter and the queen`s ship were both converted to polygons and imported into formZ from autodessys (Columbus, OH) running on Macintoshes.
In addition to the space ships, the modelers used Studio to create 18 different pods for the pod race, which was no small task. "Anakin`s pod had 3700 surfaces," Paul says. "We learned how to be more efficient, though: The number of surfaces in Sebulba`s pod went down by 1000." To further help save time, various pods were created with low, medium, high, or "hero," resolutions, depending on how close the camera got to the pod. Paul also applied techniques such as trims from his industrial-design background. He used trims in particular for the complex destroyer droid model, which folds up and compresses into a wheel. "ILM hadn`t used trims before; their 3D paint software didn`t work with them," he says, "so to create a hole, they had to create new patches." Thus, ILM`s R&D department updated its Viewpaint software to allow painting on trims. In addition, the painting software incorporated projection mapping, which opened the door to polygonal models. "For hard-surface models, in some cases it made a lot of sense to use polygons," Paul says.
One of the most complex models Paul worked on was the droid rack, a huge machine that delivers the battle droids to the battleground. "I got to animate the mechanism that drops the droids into formation because I was the only one who knew how it worked," says Paul. For that, he used Alias\|Wavefront`s Maya software.
Like the droid rack, many models appear only briefly onscreen, but that did not lessen the attention to detail. Take Jabba`s mother, for example. During her 15 seconds of fame, she`s half-hidden behind Jabba. Even so, if you watch closely, you`ll see that she has as much detail as her son. It`s a lot of effort for a few seconds on screen. "Tell me about it," laughs modeler Markell, "but it was fun."
Next month, in Part III of our Star Wars coverage, we look at the new technology created for the movie.

Only the people in these two images are real. The sets and the droid troopers were modeled at Industrial Light & Magic.
To help make the biggest fish in the undersea Gungan world look menacing, the modeler sharpened its teeth and gave it tiny eyes.

A few of the 18 pods, which are CG models when moving, are lined up (at right) for the start of the race. The pod racers are always digital, although that didn`t help the racer below get off the ground.

The queen`s ship and the Naboo N-1 Starfighter pictured were modeled using techniques familiar to computer-aided industrial designers.

ILM modelers created special shapes for Jar Jar`s tongue, and carefully folded the geometry in Jabba the Hutt`s model to create the folds in his skin.
Good Moves
Some animators call it the devil`s rotoscope. Although motion capture was used successfully for Titanic, it`s been the exception rather than the rule for visual effects. At ILM, mocap was tested, but not used for 101 Dalmatians; tried for Casper but used only for one shot of Casper`s mouth, and also used in a quick shot for Spawn. Then Star Wars Episode I made it viable to consider motion capture in a big way. "There were so many scenes that needed a volume of animation," says Jeff Light, who helped set up ILM`s motion-capture studio and became motion-capture supervisor for Episode I. The studio now has a well-utilized Oxford Metrics` 20-camera Vicon 8 optical motion-capture system, from Vicon Motion Systems (Tustin, CA). "We captured hundreds of performances," says Seth Rosenthal, motion-capture supervisor for the studio.
For Star Wars, motion-capture data helped create animatics (animated storyboards) for previsualization, became reference material for keyframe animators, and provided animators with motion cycles they could use for the Gungan soldiers and battle droids. To create the animatics, Light acted out the entire film while wearing Ascension Technology`s (Burlington, VT) wireless magnetic motion-capture system. Keyframe animators working on Jar Jar had reference data captured from actor Ahmed Best, who wore optical markers for the Vicon system, as did Light and James Tooley, who performed the Gungans and droids respectively. "James and Jeff could perform to the plate," says Rosenthal. "They knew clearly what the shots entailed because they were responsible for them. We were able to do emergency shots in the morning and see them in dailies a day or two later," he adds.
This animation efficiency was due in part to software ILM developed. "I didn`t like motion capture any more than any animator would," Light says, "so I decided I`d [create a system] from an animator`s perspective." As a result, when an animator gets motion data, it`s already applied to the hierarchy of the character, so the animator can easily use all or any part of it.
Now that Star Wars is over, ILM is using motion capture for other projects. Already the motion-capture studio has bee Now that Star Wars is over, ILM is using motion capture for other projects. Already the motion-capture studio has been put into action for another movie, The Mummy, and has helped design a creature for a game developer.
"Mocap" data helped animators move the droids.
Barbara Robertson is West Coast senior editor for Computer Graphics World.
Computer Graphics World July, 1999