Issue: Volume: 29 Issue: 12 (Dec 2006)

She-Dragon


The film Eragon has two stars: a teenaged boy named Eragon and a blue dragon named Saphira. The boy is performed by actor Edward Speleers; the dragon by visual effects studios Industrial Light & Magic (ILM) and Weta Digital.

Directed by Stefen Fangmeier, the 20th Century Fox film is based on the book Eragon, written by then 15-year-old Christopher Paolini. The fantasy, the first book in a trilogy, includes elements reminiscent of both Star Wars and The Lord of the Rings. It centers on the coming-of-age of a sentient dragon and a boy who would become a Dragon Rider. At the end, together they defend their homeland against an evil king (John Malkovich) with help from a storyteller named Brom, played by Jeremy Irons.

The film is Fangmeier’s directorial debut. Given Fangmeier’s background as a visual effects supervisor at ILM, where he won three BAFTA awards for best effects (The Perfect Storm, Saving Private Ryan, Twister) and received three Oscar nominations (Master and Commander: The Far Side of the World, The Perfect Storm, Twister), it might seem that he would create an effects-laden film. Not so. Eragon’s total shot count reached around 400, divided nearly evenly between ILM and Weta, with Furious FX and Cinesite adding touches of magic.

"I like the feeling of reality in Jurassic Park, which was shot in Hawaii," Fangmeier says. "It grounds the audience in something they can relate to before taking them into the fantasy story. There are dragons and people with magic abilities in Eragon, but the rest is reality-bound."

Although the shot count didn’t reach the 800-plus number common to many fantasy and science-fiction films, for the visual effects studios, the assignment was fantastically difficult. We follow the digital lead character, a blue 12-foot dragon with feathered wings, from birth to adulthood. During the film, her behavior changes from that of a puppy to a predator that fights fierce battles. The studios didn’t make her talk—she and Eragon communicate telepathically, and the audience hears her voice (Rachel Weisz), but there’s no lizard lip sync. The flying reptile delivers emotional scenes using mammalian facial expressions and body language. "She’s the second biggest character in the movie," says Samir Hoon, visual effects supervisor at ILM. "It was a challenge to make her look real."

ILM handled the shots of Saphira from hatchling to adult as she and Eragon come of age together and bond—emotional shots of Saphira as a caring guardian and scenes of Eragon flying on the dragon. During the "unhappy flight," Eragon struggles to stay on the dragon’s back. During his first attempt to ride on the flying dragon’s back, he struggles to hang on. For this sequence, the studio composited live-action bluescreen elements of the actor on motion rigs and wires into background plates. Sometimes they replaced Eragon with a digital double, but Saphira was always digital.

The Weta team, led by visual effects supervisor George Murphy, handled the transformation sequence that moves Saphira from fledgling to adult as she flies alone through the clouds, the opening sequence with multiple dragon riders fighting in a fiery landscape, and the end battle during which a helmeted and armored Saphira fights a grotesque smoky beast. "The diverse range of creature and environmental challenges had us draw upon almost every 2D and 3D discipline," says Murphy. The beast hidden inside plumes of black smoke, for example, needed to have a convincing mass and scale as it fought Saphira. And as for Saphira: "We took every advantage we could of ILM’s existing model and texture work, but we still had to run Saphira, at least in part, through most of Weta’s normal creature development cycle."

Baby Blue

We first meet Saphira when she hatches from what Eragon thought was a stone. The awkward blue baby pokes her head out of the shell, tumbles free, and tries to stand. For this and other shots, ILM animation director Glen McIntosh looked for inspiration in the animal world. "Saphira is a creature of fantasy—she has arms, legs, and wings—so her structure is different from anything in nature, but we like to find moments based in reality to give the audience an anchor point."


Rather than create a bright-blue dragon, ILM reproduced the grayish-blue color of large animalsbut with hints of iridescent blue. Animators used such animals as lions for reference. Image courtesy ILM.

McIntosh turns to his computer, plays a video of a Siberian tiger rolling on her back, and then switches to footage of a newborn fawn struggling to stand. "I used the Siberian tiger as inspiration for the baby rolling out of the egg," he says. "And even though the fawn’s legs are longer than Saphira’s, it was good reference."

Once Saphira is out of the egg, Eragon tries to feed her milk. The hungry reptile snatches a rat instead and gobbles it down like an eagle eating a fish. To add an endearing touch, the animators had her smack her lips. "She’s adorable," says Michael DiComo, digital production supervisor. "It’s a cute sequence." Effects artists helped make her look appealing by cranking up subsurface scattering to make her reptilian skin seem softer and thinner, making her head fuzzy, and her wings downy. She also has a baby’s big eyes.

Her eyes and facial expressions, of course, played a big part throughout the film. "She’s smart," says Hoon. "She has emotions. She participates in conversations; she helps Eragon. But, it all has to happen without any audio. Her face is not fleshy; she has scales. We had to keep her eyes alive without making her look human, so she has a reptilian pupil, but a kind look."

When she’s young, the animators created puppy-like behaviors for Saphira, and on set, Fangmeier suggested that the actor playing Eragon remember his own dog as a puppy. "We had animatics," Fangmeier says, "and Ed [Speleers] was quite natural interacting with something that wasn’t there, but that helped."

As Saphira ages, the animators continued using a dog for reference, and other animals as well. On the ground, she stalks like a lion; in the air, she flies like an eagle. But the animators sold the dragon’s emotional performance with her eyes and face, not broad body movements. "Her eye movement is half dog, half human," says McIntosh, "and the meat around her nostrils crunches up like that of a dog or a lion." She narrows her pupils, darts her eyes, and adjusts her jaw when she’s listening. When she’s disgusted, she snorts like a horse. "But, she never smiles," McIntosh adds. "That looked too human."

McIntosh’s team of animators worked in Autodesk’s Maya or ILM’s Zeno, using controllers to expand and contract Saphira’s neck muscles, tense her cheeks, curl her tongue, and raise and lower her eyebrows. "These things are subtle, but if they’re not there, they take away from reality," he says.

For shots of Eragon and Saphira flying together, ILM fed data from animatics into a motion-control rig that Speleers rode; the rig mimicked the movements of the animated dragon. "It was quite challenging technically," says Fangmeier. "We used the same rig in London that was used for the Hippogriff in Harry Potter, but I think we took it to the next level in terms of complexity and the dynamics of the camera."

Scales, Feathers, and Skethers

To create the dragon, modelers at ILM used subdivision surface meshes in Maya. "Modeling with subdivision surfaces is a relatively new approach for our company," says Aaron Ferguson, creature supervisor. "The model supervisors developed new ways to handle and mirror partitions that allowed us to merge several partitions at once."

Techniques such as that helped the crew deal with ongoing revisions. "We had to swap the dragon in and out many times after we were in shot production," adds Ferguson. "Being that flexible was an interesting challenge."

ILM sent the model and texture set to Weta for its shots. "We didn’t have to do anything to the model," says Weta’s Guy Williams, co-visual effects supervisor. "We just spent a few days converting the way the texture assignments happen for our specific pipeline."


To fly Edward Speleers onSaphira’s back, the effects crewused a motion base programmedwith animation data.

The major change for Saphira was a decision to make her wings bird-like rather than bat-like; the studio requested that change after the dragon had been in production for nearly a year. "It came as a big surprise," says Ferguson. "We had to go back and redo shots." Twice. At first, the new bird-like wings looked like those of the character Angel in X-Men. Then, the feathers evolved into the dragon’s final look. They stiffened, became more like scales, and moved toward the edges of the wings. Even so, the creature had 500 of these new feathers, which the crew dubbed "skethers," on each wing.

"The client liked the feathers, but wanted them to look stronger," says DiComo. "We used directional displacement for the scales, then a transition to two or three rows of modeled scales, then the skethers. The skethers could bend and flutter, but we couldn’t have them separate much."

Ferguson’s team used a procedural rig and simulation systems to control the feathers and the creature’s skin. "We had several different solutions for the feathers," says DiComo. "We had simulation solutions and rigging solutions. Some rigging solutions worked well for closing wings, others for flapping motion." Cloth and hair simulations also moved the dragon’s mane, the feathers on her head, and dangling bits of skin on her chin and elbows. Flesh and "flesh light" simulations pushed her muscles and pulled her skin.

To help speed the simulation process, the technical animators could select parts from various simulations rather than re-simulating a shot. For example, they could blend a skin simulation from Saphira’s face with a skin simulation on her body that they ran at a different time. "It’s an interesting and fun way to use simulation," notes Ferguson. "We didn’t always have to start from scratch. We could put stuff in and pull stuff out."

Additionally, the animators could tweak the simulations. "After the simulation is run, we have a tool that inverts the simulation data back through enveloping [skinning] and saves it in a rest-position state," Ferguson says. "So we could make minor changes to the animation without affecting the simulation data." Painted maps specified areas that simulation forces would not affect, to keep the skin from tearing when Saphira flew.

Fly Like an Eagle

Saphira’s first flight happens when she’s approximately 15 years old. "Eragon is running with her through a grassy field, trying to get her to fly, and she starts dog-pedaling with her legs," Williams says. "It’s a beautiful little character moment, this adorable dragon trying to fly."

 

At TOP: To weave Saphira through Tronjheim’s towers during a fast-movingbattle, Weta Digital used software created for King Kong’s New York City tobuild the complex environment as seen in the fi nal shot (Bottom).

Weta created the juvenile by finding a middle ground between ILM’s baby and adult dragon models. "It was a challenge getting her to be the right age and looking like a girl," Williams says.

Once in the air, the dragon pedals away quickly, like a child on a tricycle, through the clouds. We see her in a flash of light when she pops out of the clouds; she looks almost incandescent. She grows larger with the second flash and becomes an adult with the third. And then she silhouettes down in a barrel roll and lands behind an amazed Eragon as a fully-grown dragon.

To create the clouds and to transform the live-action plates into cloudscapes, Weta used layers of elements on cards that the group assembled and controlled using a proprietary tool called Psycho. With Psycho, effects artists positioned 3D cards in a 2D package, such as Apple’s Shake, and used the camera from tracking or from animators to place clouds in the shots. Depth rendering helped foster the illusion that the blue dragon is inside a cloudy-white volume. To create Saphira’s middle size for the transformation, Weta modeled a blend between a scaled-up juvenile and a scaled-down adult.

"We buried a lot of the transformation in the clouds," says Williams. "We also did a variety of particle passes, rendering passes, and the kind of stuff that you can do in composition, like blooming halation camera effects. We went bold and heavy, and hid it with light."

When Saphira is young, the studios colored her bluer than when she’s an adult, both ILM and Weta having learned from previous experience creating odd-colored characters in films—the green Hulk at ILM for The Hulk and the blue Fell Beast at Weta for The Lord of the Rings. ILM’s Jean Bolte painted texture maps with a complex palette of grayish-blue tones used by both studios. "Big creatures in nature are gray," says DiComo. "So we gave her a neutral undercoat and a golden beige belly with magical blue kicks of iridescence."

For rendering, technical directors John Helms and Kevin Reuter at ILM used Pixar RenderMan’s additional output variables (AOV) to break out such individual components as depth from camera, ambient, diffuse, and specular lighting. Compositors then blended the layers and adjusted the lighting as needed. "That way, if something needs to change, we don’t have to go back and re-render everything," says DiComo. "We can render just one layer."

Although Weta used a directional displacement technique similar to that used at ILM for creating scales in rendering, the studio has a different lighting philosophy. "We have an extensive comp department, but we render one big beauty pass," Williams says. "We like the 64-bit float fidelity in rendering, and we like to put the burden on the lighters to get the lighting looking right."

As for the scales: "You move a directional flow field on the body to slant the displacements so they don’t look like they’re carved in clay," Williams explains. "We’ve done directional displacements in the past, but we got the idea to use those tools on the dragon from ILM."

Smokin’ Battle

Weta’s primary work centered on the end battle, much of which Fangmeier filmed in an enormous abandoned quarry outside Budapest, Hungary, using a cast of 400 extras. The quarry represented a hollow mountain-city built inside a fictitious volcano, in which the rebel Vardens hide from the evil empire. The city, Tronjheim, has thousand-foot towers decorated with jewels and treasures. It’s attacked by Orc-like Urgals, led by Durza (actor Robert Carlyle), a human possessed by spirits. Weta extended the quarry with digital matte paintings and, in some sequences, created the entire background digitally, added extras using Massive software, animated Saphira, created and animated a magical evil beast, substituted digital doubles for the actors when the live-action elements didn’t work, and composited the shots in Shake and D2 Software’s Nuke.


For the thousands of torches lighting Tronjheim’s open walkways, Weta used fl ame elements on cards.Image courtesy Weta.

The battle ends with the attack by Durza and the Urgals, and some of Williams’ favorite shots happen during this part of the action sequence. "It’s like a theme park ride," he says. "Saphira is tucking and weaving and dodging, barely missing the towers, and every few seconds Durza throws a fireball and blows out entire swaths of buildings," he says. "It’s one of those things you groan about when you think of all the technical ramifications, but it’s a beautiful thing."

The studio relied on custom software developed for King Kong’s New York (see "Long Live the King," January 2006, pg. 16) to produce Tronjheim’s hundreds of towers with flying bridges 200 feet in the air. The crew built the Varden’s little huts in the same way by using the procedural New York system to texture and weather the 3D models. 3D sequence supervisors Jake Lee and Keith Miller set up the environment, creating projections for the matte paintings. Erosion software, also used for New York, aged the buildings by raining particles onto the surface that streaked down the sides. Torches capped with flame elements on cards lit the open walkways.

"The Tronjheim environment is really complex," says Williams. "We built it so it could be destroyed with our destruction software. With this software, you give it a model and tell it where you want the force to occur. It breaks the model and does the crumbling and intersections for you. It can handle thousands and thousands of rigid bodies colliding."

During the battle, Saphira incinerates the attackers. They attack again. Saphira blasts them into smoldering ashes. Then, Durza casts a spell and summons a creature from the ashes of his army. Fire swirls into a mushroom fireball that becomes a black cloud. Inside is an amorphous, massive face and a big row of teeth. Durza rides on top. "It’s a magical construct made up of bad things," says Williams. "It can’t see where it’s going. It’s constantly erupting thick, black, oily smoke, and little pieces of itself erode, decay, and drop off. It’s constantly re-created at the same time."

Weta started with a model from ILM and then, using reference footage of ash clouds flowing down the side of an erupting volcano, formed the monster. "We expected this would be the hardest work and would have the longest render times," says Williams. "Because we had a short development time, we opted out of creating a system based on a ray marcher. Instead, three of our lighting TDs developed a variety of clever particle methods to build the smoke. This gave us more freedom to art direct the result and ensured a high level of detail."

The creature the technical directors worked from had the head of a hammerhead shark, with radar domes on the sides like ears, a bat body with three legs on each side, and a gigantic mouth. No eyes.

Christian Hipp targeted local particle emissions from this grotesque body to create a creature constantly dissolving into smoke in a windswept way. To do this, the lighting TD lofted Maya hairs off the creature, tubes that were flared at the end like a trumpet where they touched the creature, and emitted particles using each tube as a goal. "That produced tendrils of smoke, but it was complex and heavy," says Williams. "So he grew about 60 tubes of this smoke and then, using our Kong hair system, grew another 100 solid surfaces that he textured with smoke and rendered with transparency."


With the blue-gray Saphira fi ghting an aerial battle at night against a dark, smoky, evil creature,Weta used lighting to enhance the action and direct the viewer’s eye.Image courtesy Weta.

Lighting TD Sam Bui created a sprite system that produced the black, oily cloud left behind as the creature moves; tendrils stretched into the cloud. "Exotic noise fields made the sprites look otherworldly," says Williams. "We wanted the smoke to assume a magical quality, as if it had a character of its own." Kevin Romond, the third lighting TD, caused the creature to constantly emit pebbles and rocks that stream smoke behind as it moves. "As they break down, they stream even more smoke," adds Williams.

The crew rendered all the smoke layers together because they wanted the elements to look like they transitioned into one another. You can’t do opacity matting with sprites," notes Williams. "It would be exponentially expensive."

Although Weta largely focused on action shots and the transformation scene, a sequence during which Saphira crashes to the ground in the battle provided acting opportunities. "It’s a moment when she and Eragon talk to each other," Williams says. "It’s almost as if you’re talking to yourself in a mirror, but just thinking the thoughts without moving the lips. There are lots of beautiful moments in this sequence."

Murphy agrees: "Throughout our core work on the nighttime aerial battle scenes and the more intimate performances that frame this sequence, we strove to give a strong sense of physical presence to our CG characters, and I believe we succeeded."

Even though this film isn’t laden with visual effects shots, the digital lead, digital battles, and digital backgrounds qualify this film as a "visual effects film," albeit one with judiciously applied and carefully designed effects. As a result, Eragon’s effects help bring the fable to life and keep the audience rooted in a believable story without losing the magic.

"I think this is an inspirational story," says Fangmeier. "Hopefully, the audiences will connect to it."

Barbara Robertson is an award-winning writer and a contributing editor for Computer Graphics World. She can be reached at BarbaraRR@comcast.net.

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