Big, Bad Wolf
Issue: Volume: 28 Issue: 10 (October 2005)

Big, Bad Wolf

Nearly everyone grew up reading the edgy fairy tales from Wilhelm and Jacob Grimm: “Hansel and Gretel,” “Cinderella,” “Little Red Riding Hood,” “Snow White,” and many more. In the feature film The Brothers Grimm, digital and practical effects enabled director Terry Gilliam to give the folklore a darker, more sinister look and feel as a number of these tragic, familiar characters come to life on the big screen alongside other heroes and villains-some live, some CG.

The action/adventure/fantasy film places its own spin on the tale of the real Grimm brothers, as the legendary sibling scribes travel the medieval countryside offering villagers protection from nonexistent monsters and demons. Soon enough, though, the con men’s stories are put to the test when they encounter a real magical curse within an enchanted forest. Woven into the story fabric of the film are threads from the actual Grimm tales, including a bizarre slant on “Little Red Riding Hood” that features one of the movie’s most pivotal characters, and the most complicated to create: the wolf.

In keeping with the movie’s theme, the animal is far from ordinary: It’s a werewolf. In animal form, the beast-created using CG-is a vicious, spellbound hunter serving an evil queen. In human form, the creature assumes the identity of the woodsman (played by actor Tomas Hanak), who is heroine Angelika’s father. During the transition from beast to man, however, the woodsman was played by a digital actor.

“Creating a CG wolf was difficult in and of itself, particularly when it came to the fur,” says John Paul Docherty, digital effects supervisor at Peerless Camera Company, a London visual effects facility formed by Gilliam and the film’s VFX supervisor Kent Houston more than two decades ago during the making of Time Bandits and the Monty Python movies. “In addition, we had to have a wolf that was vaguely manlike in its appearance. Also, transitioning the model to human form added another dimension to the task’s overall complexity.”

Initially, Gilliam had planned to use an animatronic to accomplish all the wolf close-ups, and employ CG for what were to be no more than seven fairly wide shots of the animal leaping and such. However, that number soon grew to almost 50 and included a close-up of the wolf’s eyes that filled the entire theater screen. Under those conditions, the animatronic “just didn’t stand up,” says Docherty. “And, it didn’t look like anything Gilliam had in mind. It looked far too tame. So the animatronic ended up in the bin.” As a result, the wolf model was crafted entirely in 3D with Softimage’s XSI.

Yet, even the initial task of designing the animal became extraordinary. “The animatronic wolf looked like an Alsatian dog,” says Docherty. “If you are familiar with Terry Gilliam’s style (12 Monkeys, The Adventures of Baron Von Munchausen), then you would know that nothing could be further from a Terry Gilliam wolf than a dog-like animal. It had to be mean, with knobbly limbs and a ‘Gilliam look’ to it. That is just about impossible for the effects crew at Artem, and downright difficult for the CG artists at a workstation.”

According to head of 3D Ditch Doy, the artists first looked at the skeletal structures of wolves, but they didn’t have what Docherty describes as “a man trapped in a wolf’s body” feel. Next, they examined horses and other animals to use as references for their model. In the end, the bone structure of the Gilliam wolf was based on those of a modified lion and revised hyena, with a large, barreled chest and skinny hindquarters-and, of course, a scary look.

For the werewolf in The Brothers Grimm, the artists had to create an animal with some human characteristics. This included the wolf’s eyes: In a crucial scene, the heroine recognizes them as belonging to her father.

Within XSI, the group created two different skeletal structures: a quadruped for the wolf and a biped for the man, which was used immediately following the beast’s transition to human form. “We built our rig for the wolf to reflect a creature that walks on all fours. Then, during the transformation, the bones in the shoulders and torso break apart, and he stands upright,” says Doy. “But that didn’t always work in the early tests, and it didn’t look very menacing.” Only after a tremendous amount of R&D and by utilizing a number of cheats, the team finally was able to adapt the quadruped rig for the desired transitional action.

The animal’s supernatural animations, many created with XSI’s animation mixer, also required the group to think outside the laws of nature. The concept that the creature was superhuman and nearly inertia-less resulted in grand leaps and aerial feats. “But it soon became apparent that the wolf was not threatening enough as it landed, so it kept getting pulled back more and more into the realm of this large heavy animal,” notes Doy. However, remnants of the animal’s lighter version are still present in a few scenes as it bounds through the woods, seemingly lighter than air.

At times, though, the team struggled to determine whether the model’s animation should be styled as the wolf or as the woodsman, especially immediately before or after a transformation. In one such sequence, the creature drops down to all fours and catches an arrow in its teeth. “We must have animated that more than 50 times, and the issue always became whether it was more man or animal at that point,” Doy says. The final animation (favoring the animal) was only determined at the eleventh hour.

“There are a number of times when that situation arose,” adds Docherty. “They were tough calls. That’s what happens when you have an animal and you sell it as a human character.”

To texture the animal, the artists used XSI’s integrated fur system, which is roughly based on Joe Alter’s Shave and a Haircut software package. Still, the group spent a good deal of time writing its own tools in order to get the simulation to work properly for handling the quantity of fur and the specified lighting.

“Most of the fur we had seen elsewhere was straggly, no doubt because of the computational overhead and the difficulty of the lighting, since fur primitives are not normal CG structures,” explains Doy. “So we did a lot of work with the [Mental Images] Mental Ray guys, particularly Thomas Zanker, who was on site at Peerless for nearly four months helping to debug the implementation of the hair renderer in Mental Ray.”

Zanker, along with Raffaele Fragapane, Peerless’s lead technical director for the wolf sequence, implemented the fur system into the studio’s render wall through a proprietary rendering system managed by Greg Ercolano’s Rush Render Queue software. Then, the group had to debug what Doy terms “a number of interesting problems” so that the fur rendered in less than six hours a frame for a single 2k shot. In the end, the team streamlined the process by optimizing the code, allowing the artist to reduce the rendering to between 20 and 30 minutes per frame.

For lighting, the group rendered individual light passes, using what Docherty describes as a cinematographic rather than a CG approach. “Under normal circumstances, this is not the way to go because fur is so expensive to render,” saysDocherty. “But we had a situation whereby if we changed the viewpoint and changed just one light, the creature went from this ferocious wolf to a lovable pet.” Taking advantage of the reduced rendering times, the team decided to layer the light passes, which lead compositor Dennis Jones compiled inside Autodesk Media and Entertainment’s Discreet Inferno and Apple’s Shake.

As a result of this method, the team eliminated the usual crackling that occurs with rendered fur. “In the close-ups, the creature has a full coat of hair, and the hairs reacted exactly as we wanted them to,” Docherty says.

With the wolf model complete, the group turned its attention to the animal’s alter ego as it transforms into the woodsman, who wears a shabby cloak and a hat made from several wolf pelts. This transition occurs several times during the film-sometimes by firelight, sometimes in daylight.

To create the digital human used in the conversion process, a crew from Eyetronics digitally scanned the actor dressed in the bulky fur clothing. As Docherty points out, the scan did not provide the group with the fur data, but rather a template of the bulky shape. Far more important than capturing the fur, however, was acquiring the facial data, as “the devil was in the details” of the face, specifically the cheekbones and the eyes: At a climactic point, the heroine looks into the eyes of beast and recognizes them as those of her father. “So it was vital that we had believable, human-looking eyes, which are seen in close-up during a flashback moment.”

Similarly, the digital cloak had to match the virtual version, particularly in the scenes when half of the garment is real, and the other half is CG. The artists re-created the actual cloak by hanging procedural bits of CG cloth with attached fur onto the virtual actor. In fact, the digital pelt of the wolf was crafted from the same CG fur used to make the coat and hat for the virtual actor. As Docherty points out: “It’s difficult to make a furry garment look dangerous.”

(Top) The CG wolf, created in Softimage, transforms into a CG human, before the real actor steps in. (Bottom) The virtual actor, as well as his cloak and hat, had to match those of the real actor.

The team built analog strips of the pelts in CG that tore from the skin of the wolf as it turns into the man’s coat and cap. “We originally planned for the wolf’s head to become the man’s head, but the odd shape of the hat made that difficult,” says Docherty. “One day we were experimenting, and we sort of ripped the animal’s head back and had the man’s head emerge from the wolf’s neck region. We all agreed that was very odd. But it grew on us, and eventually it became a big part of the transformation.”

While the wolf proved to be the most challenging in terms of creating the film’s effects, it was not the only creature Peerless had to tangle with for the film. (Assisting Peerless in the film’s effects was Artem.) The artists also crafted the mud mimic, an amorphous creature that swallows children, as well as a host of digital set extensions and other tasks, which added up to more than 800 CG effects shots.

“Typical big, spectacular, LA-style effects are not Terry Gilliam’s style,” says Docherty. “His are more three feet in front of you and disturbing.” To that end, The Brothers Grimm werewolf does not disappoint.

Karen Moltenbrey is an executive editor for Computer Graphics World.