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Issue: Volume: 31 Issue: 8 (Aug. 2008)

Extreme Effects - Hellishly Great Effects


The comic-book superheroes Hellboy and Batman both fight evildoers, but the similarities end there. Hellboy is a supernatural being who couldn’t exist in our real world. Batman is a (fictional) real man, a billionaire who uses technology as a weapon. Hellboy lives in a fantasy world; Batman fights crime in Gotham City, a fictional version of a real city. Perhaps, even, Chicago.
 
The directors of the two latest films about these icons, Universal Pictures’ Hellboy II: The Golden Army and Warner Bros.’ sixth Batman film, The Dark Knight, showcase those differences.
 
Guillermo del Toro, who is from Mexico and had previously directed Hellboy and Pan’s Labyrinth, populates Hellboy II with visually exciting mythological creatures who have eyes in places you’d never expect. British director Chris Nolan, who had previously written and directed Batman Begins and Momento, pits Batman against The Joker on the gritty streets of Gotham City, and dives deep into Batman’s soul.
 
Despite these differences, both directors focused on practical effects for their fast-moving action flicks, using CG to enhance and expand those effects. Del Toro put men in “rubber suits,” using animatronics, prosthetics, and makeup to create many of his creatures. Nolan flipped and crashed real cars and exploded real buildings.
 
Even so, Hellboy II had approximately 1100 visual effects shots, with Double Negative giving thousands of bizarre creatures their often-horrific action and adding visual complexity to the animatronic suits and fantastic environments.
The Dark Knight had approximately 700 visual effects shots created at Framestore CFC, Double Negative, BUF, and Cinesite, intense complex shots with CG effects that needed to precisely match live-action footage shot in IMAX resolution, even down to the surface of the roads.
 
To help their artists become effects superheroes, most of these studios used real-world off-the-shelf software, and all crafted fantastic new tools and techniques, as you’ll see in the following two articles, which pull back the curtain on the extreme effects in Hellboy II: The Golden Army and The Dark Knight


Imagine Pan’s Labyrinth director Guillermo del Toro’s version of hell on earth and you have an inkling of the visual feast in his latest film, Universal Pictures’ sci-fi action thriller Hellboy II: The Golden Army. Written by del Toro and Mike Mignola, who wrote and illustrated “Hellboy,” the original Dark Horse Comic, the sequel to del Toro’s 2004 Hellboy pits a mythical world against humanity in a bid to rule the planet.

Actor Ron Perlman once again plays the tough-talking, hell-spawned hero who must save the earth. Fighting alongside the bright red and appropriately horned Hellboy are two other supernatural beings in the FBI’s Bureau of Paranormal Research & Defense (BPRD): the psychic, fish-like Abe Sapien and the fiery Liz Sherman, played by returning actors Doug Jones and Selma Blair.

But even more fascinating are the dangerous, strangely limbed, multi-headed creatures rising from the myths, their eyes in odd places. As is del Toro’s wont, many of these odd gods and characters are men wearing rubber and animatronic suits and prosthetic makeup. But, some are not, and for these and other effects, del Toro turned to Double Negative.

Mike Wassel led a visual effects crew of approximately 250, many of whom began working on the project in October 2006. Eamonn Butler supervised animation. Andrew Chapman, Justin Martin, and Adrian De Wet supervised the digital effects, with Chapman and Martin concentrating largely on 3D and De Wet on 2D. All told, the film has approximately 1100 shots, a small portion of which Double Negative subcontracted to Cube Effects, The Senate, Lipsync, and Baseblack. The creatures, though, came alive at Double Negative.

“Our main challenge was the number of creatures,” says Martin. “We built a lot of different creatures, and we had multiple creatures in some shots.” Multiple is an understatement.

Double Negative’s digital creatures with the most screen time are the tooth fairies, the golden army robots, and the Elemental. Two out of the three appear in multiple versions: Thousands of tooth fairies burst into some shots, and 80 hand-animated robots fight in others. As for the Elemental, the foliage-covered creature stands nearly 10 stories tall.

The studio created other creatures as well, built digital environments, enhanced Abe’s and Liz’s performances, and added complexity to a largely practical “troll market” with CG pixies that re­semble those in Pan’s Labyrinth and Striders that look like headless elephants on giraffe legs with pointy feet. “They’re a good example of what we had to do on this movie,” Butler says of the Striders. “They’re in two shots, and they took six months to build. But the design lent itself to experimental animation, and it works. They make the troll market sequence look incredibly diverse, which was the point.”

Tooth Fairies
At first glance, they look benign, even cute, but these fairies don’t leave money under your pillow. They’re tooth fairies because they eat your teeth, and they eat your bones. They have four pincer-like legs, two humanoid arms with nasty clawed hands, four paper-thin wings that look like leaves, and a big head. They’re a little over eight inches tall. And, they appear throughout Double Negative’s first big sequence.

We first see one in an auction room digging up a tooth in a pile of brown muck. “They’ve eaten everyone,” says Butler. “We don’t show that, but Hellboy and the other BPRD agents put two and two together when the cute fairy turns and attacks them. All the tooth fairies hiding in the walls bust out and attack. They go for the teeth first, but they eat everything in front of them. And, there are thousands, landing on the agents, crawling into their mouths, biting, pulling their hair. Guillermo described them as vicious little Chihuahuas.”

One tooth fairy looks mean enough, but thousands burst from the walls and attack the BPRD agents. To help animate the attack, Double Negative designed Swarm, a crowd-simulation system based on smart particles.
 
Creating this technically difficult scene required extensive body tracking and rotoscoping to fit the digital shadow-casting fairies into the plate and onto the actors’ clothing. “Hellboy stamps on one tooth fairy and squishes it,” says Butler. “And another eats a guy to the bone. It’s gruesome. But, it was a helluva lot of fun to animate.”

Chapman worked on set with Wassel, ori­-enting between one and three HD  “wit­ness” cameras to capture alternate angles of the live action for this and other sequences. “We covered most of the shots even if they didn’t have CG because we often added to the practical effects,” he says. “The other angles make it easier for the tracking department to work out where everything and everyone is.”

Digital doubles, which were matched to actors tracked in the footage during postproduction, helped animators attach the tooth fairies accurately. “All the main actors had digital doubles even if we only used the doubles for roto-animation,” Chapman explains. “And, we had a generic human model that we scaled to fit background actors.”

Animators performed some hero tooth fairies, 2D artists created the illusion of fairies pulling and gnawing on cloth, but to create the multitudes, Double Negative designed a crowd-simulation system implemented in Autodesk’s Maya that the studio called Swarm. “It’s a smart particle system that determines where they travel and land,” Butler says. “The particle system drove a second system that switched between half a dozen flying behaviors. It was smart enough to blend into another animation when a fairy landed.”

When fewer than 20 fairies are on screen, animators worked with one at a time. To control a swarm, they animated groups of 60 by switching from cached geometry for groups they weren’t animating to animation rigs for those they were. “It wasn’t real time, but it was workable,” says Butler.

Elemental, My Dear Hellboy
The creature called Elemental starts as a magic bean that grows quickly and bursts through the ground in Brooklyn nearly 10 stories tall, shaking foliage, dripping water, and giving off steam. He spots Hellboy and runs down the street, trashing things as he goes.

Shaped like a tree trunk, with leaves and vines covering his body, Elemental has long, hanging tentacles that wrap around and lash out at things. One tentacle has a clubfoot that acts like a limb; sometimes the tentacles act like hands. We catch only glimpses, never the whole creature. Animators moved the tentacles using spline-based controls rigged in Maya on top of a standard IK setup. “We needed total control over the shape,” Butler says.

The foliage, Double Negative’s idea, helps sell the creature’s scale. “The vegetation is a recognizable scale, so it instantly made him look large,” Chapman says. “And, it added detail.” To animate the vegetation, the effects artists devised procedural techniques in Side Effects’ Houdini. “We’d bring the animation into Houdini, apply the vegetation, and then send it back to Maya for lighting,” explains Martin. The studio uses Pixar’s RenderMan for rendering geometry such as this, and relies on its own DNb renderer for volumes.

The Elemental sequence takes place on a live-action set in Budapest, Hungary, and ends with Hellboy on a very tall hotel sign holding a baby. The sign, however, was on the ground when filmed, and Double Negative added the digital city. “That sort of digital environment work is Double Negative’s bread and butter,” Chapman says. “Once you invest the time into putting a pipeline in place, it’s relatively simple. I think we almost take it for granted.”

Golden Robots
In the film’s climactic action sequence at the end, 12-foot-tall killing machines emerge from golden eggs. “They’re huge and powerful,” says Butler, “but they move with agility and dynamism. They are true badass bad guys, so we came up with ways to give them attitude. They push each other out of the way aggressively. And, they fight.”

To unfold the big, golden machines from the tiny eggs, the animators worked backward, cheating the mass to reorganize their bulk into an egg shape. When standing, each robot has at least 70 moving pieces. “I’d hate to think how many pieces,” says Martin.


Brian Steele is Wink. Double Negative blinked Abe’s rubber-mask eyes and gave Wink flexible facial expressions.
 
You can see the clockwork mechanism whirring behind the robot’s ribs, all its little cogs moving and glowing red-hot. The heat causes each robot to snort steam through its nostrils, which the effects team created using fluid simulations and the volumetric renderer. More difficult was the robots’ nasty habit of reforming after being broken apart. In one sequence, the robots fight each other, sending chunks of gold flying. Then, they put their arms back on, pull themselves together, and set their heads back onto their shoulders. Rigging was a massive undertaking.

“First, we got a basic animation rig working,” Martin explains, “then we worked on the secondary stuff. We created custom rigs on a shot-by-shot basis.”

For the clockwork mechanism, the riggers devised a procedural system that moved the cogs based on the animation, and rigid-body dynamics sent the cogs flying during the fight. In addition, the team used NaturalMotion’s Endorphin to help perform the fighting robots. “We’d do a pass with Endorphin’s dynamics to see what that looked like,” Butler says. “If it worked, we used it. If not, we keyframed over it.”For one sequence during which the robots climb a staircase, animator Jay Davis devised a technique to simplify the process. First, the animators created the performances, and then modelers fit the stairs to the animation. “We wanted the animation to look cool,” Butler says. “We didn’t want to go, ‘Oh no, the stairs are the wrong size.’”

The studio’s DNasset system managed the hundreds of pieces in scenes that often had as many as 80 robots. To render the gold surface, the team used such typical techniques as reflection occlusion. Compositors working in Apple’s Shake added the steam, which the effects team had rendered using holdouts for the geometry.

Set Dressing
One of del Toro’s favorite Double Negative characters was a rat-sized creature with two heads, kangaroo legs, three arms, and a pouch. “He didn’t talk,” Butler says. “He communicated by clicking his two heads together. He was like a mascot for Guillermo. Every time he saw him, he burst out laughing.” The character, which the crew dubbed Bogart, is in only five or six shots during the troll market sequence, drinking water, scrabbling around in the dirt, and delivering a message that Mr. Wink, the cave Troll, is dead. But he added richness to the sequence. “Guillermo loved him, that’s for sure,” Butler says.

As for Mr. Wink, actor Brian Steele plays the big troll while wearing an animatronic suit. However, Double Negative gave the creature more interesting facial expressions by replacing the suit’s face with a 3D model that the animators performed. Scans provided the textural data as well as the geometry.

In fact, most of the characters in the troll market are men in suits, but Double Negative animators also inserted digital trolls and replaced parts of the sets. “It was easier than it sounds because we had the reference in the plate to match to,” Butler points out.

In addition, the effects artists lit the supernatural Liz on fire throughout the film using Squirt, the studio’s proprietary fluid-simulation software, to create CG flames. To tie the fire to her performance, the fluid solver emitted the fluid dynamics from a body track of the actor. Compositors generally worked with lighting passes to fine-tune the look, but in the last part of one fiery sequence, the fireball was practical.

The studio also blinked Abe Sapien’s rubber-mask eyes, and created a digital double for a sequence during which the fish-like being swims underwater in a tank—the actor couldn’t swim in the prosthetic suit. “We worried about the shot a lot because Tippett Studios had done it so well in the previous film,” Butler says. “But the CG team did a phenomenal job on his muscles and skin, and in adding particulate matter to the water. Two shots and it was done.”

The ectoplasmic Johann Kraus has no muscles, so to help this fourth BPRD agent leave his deep-sea diving suit, the artists collapsed the suit using cloth simulation and then released his blubbery mass using Squirt and the volume renderer.
When audiences see the amazingly fantastic creatures in the fast-moving Hellboy II, the last thing on their minds will be, “Is it CG or is it real?” But, we can imagine that is exactly what was on Guillermo del Toro’s mind. And, thanks to the efforts of the 250 artists at Double Negative, he was able to harness the digital world to achieve mind over mythological matter.

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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