Immortal Effects
 
For The Mummy Returns, ILM regenerated the mummified Imhotep and conjured up thousands of horrific new CG creatures
By Barbara Robertson 
When a movie rakes in $40 million plus during its opening weekend, what's a studio to do? Ask for a sequel. And that's exactly what Universal Pictures did with its 1999 hit, The Mummy, which ranked eighth in box office revenue that year and so far has generated $414 million. Within a week after The Mummy opened, Stephen Sommers, writer and director, was working on the sequel. That sequel, aptly named The Mummy Returns, opens May 4. Packed with even more of what people liked in the first one-high-powered action, wild visual effects, a swashbuckling hero, a beautiful heroine, really bad guys, and tongue-in-cheek humor-it could be another hit. "[The Mummy Returns] completely blew me away. There's constant action. There are constant effects. I liked the first one-but this was much more of a movie," writes Lloyd Dobler on the website, Ain't it Cool News. 
"I knew I'd have more money," says Sommers. "I sat down and said, 'I'm going to make the movie I've always wanted to make.'" 
To help make that possible, Sommers convinced most of the cast and crew from The Mummy to join him for the sequel, including stars Brendan Fraser and Rachel Weisz, who are back in their roles as Rick O'Connell, the adventurer, and Evelyn, the Cairo librarian. Sommers set the action in 1935 (10 years after the first film), married the couple, settled them in London, and gave them a 9-year old son, Alex, played by newcomer Freddie Boath. Also back from The Mummy are good guys Oded Fehr playing O'Connell's sidekick Ardeth Bay, and John Hannah as Evelyn's mischievous brother Jonathan. On the evil side, Patricia Velasquez returns, this time as Meela, a malicious reincarnation of Anck-Sunamun, the character she played in the first film, and Arnold Vosloo resurrects his starring role as the ferocious, power-hungry Imhotep. Giving Imhotep a run for his mummy in the sequel is a new character, the big and very bad Scorpion King played by Dwayne "The Rock" Johnson of World Wrestling Federation fame. Some say, however, that the biggest returning "star" of all is the effects studio Industrial Light & Magic. 
"In this movie, the 800-pound gorilla, if you will, is ILM," Sommers says. "The Mummy had an effects shot here and there. This film has more effects and a wider range of effects. We have hundreds of shots we could not have done two years ago. It's a sequel; it has to be bigger and better." 
"More effects" is an understatement. The "effects characters"-the mummified Imhotep and his soldier mummies-are back in bigger roles. In addition, thanks to Sommers' fertile imagination and ILM's effects team, new fantasy characters have joined the digital cast: fierce-looking, dog-headed warrior mummies, nasty little pygmy mummies, and a creature that's half-human, half-bug. Like the first one, this movie is filled with other computer graphics effects as well-smoke, sand, dust, scarabs-and more. 
All told, a crew of around 100 people at ILM worked on 359 shots, almost double the original estimate, and each shot seems to have a different type of complex effect. "Every shot is sort of top-of-the-rocket in terms of visual effects technology," says John Berton, visual effects supervisor at ILM. "If you go through the list of films ILM has worked on over the last five years, everything that was really interesting or difficult is somewhere in our movie, and everything that's been popularized over the last several years as a breakthrough in visual effects is in this film somewhere." 
To create many of the effects, the team had to push that rocket even further. Berton singles out advances in motion capture methodologies that improved the performance of the digital Imhotep, allowing the CG mummy to interact with live-action actors in unique and complex ways. He also cites three technical feats: the huge number of digital, dog-headed Anubis warriors in hand-to-hand combat with human actors, complicated organic simulations of plants and water, and the Scorpion King. At some point in the movie, The Rock's Scorpion King character becomes a huge, completely digital, half-human, half-scorpion creature. The half-human part is a photorealistic clone of The Rock from the waist up. He appears next to human actors and his face is in close-up shots. 
"When you encourage somebody like Steve Sommers to bring as many ideas to the table as he can, you have a full table," says Berton who also worked with Sommers on the first mummy film and before that, on Deep Rising. 
"I'd ask John, 'can you do this?'" says Sommers. "If he said, 'yes,' I deleted it instantly. I wanted him to say he'd never done anything like that." 
Follow the Mummy 
Imhotep's goal in the first film was to become flesh and blood again, and the stage in which some of the mummy's body had grown back was particularly gruesome. For that model, ILM's effects crew devised muscle rigs and simulators to move the mummy's internal organs and hanging bits of desiccated flesh, and created displacement maps to carve textures into several layers of skin fragments and bones (see "Bad to the Bone," pg. 34, May 1999). For The Mummy Returns, the effects crew resurrected that model and used it throughout. 
Despite the familiar monstrous look, Imhotep acts less as a monster and more as a character in The Mummy Returns. "We decided to have more fun with him," says Sommers. "In the last film, the camera would cut away. Now he's in the same shot as everybody else." 
And he's not simply in the shots; he's pulling strands of Patricia Velasquez's hair through his bony fingers, picking up an urn from inside a container, shoving people around. 
As before, the animators needed to create a performance for the mummified character that matched Arnold Vasloo's performance of Imhotep as a human. To help create this illusion, the effects crew decided to once again use motion-capture data from Vasloo. "This time around I was especially eager to preserve as much of Arnold's performance as possible," says Daniel Jeannette, animation director. 
To do that, the animation and motion capture teams devised a method with which they could view motion-captured data applied in real time to a simple shaded character moving on a background plate from the film. For motion capture, they used a 16-camera, real-time Vicon8 optical system, which feeds into Kaydara's Filmbox software for the realtime display. "It was a brand-new system; no one had done this," says Doug Griffin, motion capture lead. "We were capturing a feature performer, not some animator in a mocap suit. There wasn't any room for us to be slacking around." Making this work meant synchronizing and timing all the elements. "We must have gone through 10 variations to time the background plate with the motion-capture data, the audio, and the camera move," says Griffin. Eventually, using time codes and trigger signals, they worked out a way to synchronize everything during the capture session and keep the timing correct for later work on the shots. 
Due to Vasloo's schedule, the best time to capture him was the day after the live-action shoot in England ended, so the motion-capture team moved their system to England. The sequences in which the digital mummy would appear and for which Vasloo would be motion captured had been filmed earlier, first with Vasloo in the shots and then without him. The shots without Vasloo became the background plates. From these plates, ILM's matchmove team derived the camera moves used to film the shots and gave that data to the motion-capture team. Later, on the motion-capture set, Vasloo, wearing a lycra suit with between 40 and 50 reflective dots attached to it, repeated his performance from the live-action shot, working with stand-ins for the other actors and with props. As he moved, Berton and Jeannette could watch the CG character mimicking his movements in the background plate. This realtime feedback was especially critical for close-up shots, such as the one in which the mummy pulls on strands of Velasquez's hair. 
"We couldn't have done this shot without the live feedback," says Seth Rosenthal, motion capture supervisor. "Technically, it's easy to collect the data because the performance is slow. What's hard is fitting the character into the frame in close-up shots and getting the subtle interaction between the character and someone in the plate." Because the camera was so close, for example, a simple shoulder shrug or slight lean would put some of Vasloo's head out of the frame. Being able to see that happen and correct it resulted in far better performances and less work for the animators later. Eventually, Rosenthal hopes to take this system to the next step, which would be capturing data during the live-action shoot. 
Dogs of War 
Motion capture was also used to help animate the Anubis warriors, the bi-pedal, 9-foot-tall, dog-headed creatures who make their first appearance in The Mummy Returns. In the early part of the movie, thousands of fully fleshed warriors swarm over buildings and sack the city of Thebes. Later, battalions of mummified warriors battle with humans. 
For these creatures, the teams used more conventional motion-capture techniques, capturing one or two stunt people at a time in the studio to build up libraries of fighting motions the animators could later apply to the characters. Custom software written by lead technical animator Chris Mitchell helped convert data captured from human legs into motion that could be applied to the three-jointed dog legs. 
"What's brilliant about the Anubis warriors is that they are creatures that could never exist as a live-action army," says Berton. "You could never photograph them. And yet they're doing battle with an army of live-action horsemen. This is something that could never be done any other way. I love this stuff because you have to hit the mark to make it look real next to the live-action army, to make the shot look like it was photographed." 
Sometimes you see wide shots of the giant clashes between thousands of these warriors; sometimes the camera puts you in the middle of a hand-to-hand battle between the dog warriors and the humans. 
Click here to enlarge image
To create the battle scenes, Berton started in the Moroccan desert, where he had horsemen filmed attacking blue-costumed stuntmen who wore 9-foot poles on their backs. "We didn't want the horsemen swatting at the air," he says. "I think it paid off handsomely. The bad news was that somebody had to paint out all those guys. We knew that would be ridiculously hard, but it would achieve a look we couldn't get any other way." Once the blue guys were removed from the plates, the digital warriors re placed them. 
To create the Anubis warriors, the effects team borrowed technology from Im hotep's mummy model to create three different models, and also created an assortment of helmets, weapons, ear guards, necklaces, bracelets, and other accoutrements. "Be cause these guys are dark, they kind of look the same, so we had to get as much variety with these things as we could," says Henry Preston, sequence supervisor. 
Warriors in the foreground were hand-animated; those in the back ground were animated with cycles. For the latter, technical directors (TDs) placed the digital warriors on the battlefield using particles in Alias|Wavefront's Maya. Each particle was assigned animation cycles and other randomly selected attributes such as helmet and body type, number of bracelets, whether an the warrior was right- or left-handed, what weapon it carried, whether part of its face was torn off, and so forth. 
In some scenes, once frames with several thousand warriors were rendered, battalions in the resulting images were multiplied with 2D tools-essentially, a group was copied from one area and pasted into another. However, for the scenes in which 64,000 Anubis warriors charged over the sand dunes on their way to battle, all 64,000 were rendered. "We had some very specific terrain in this plate, so it would have been hard to multiply the guys," Preston says. "When it looked like we could render them in a reasonable amount of time, we did it, and I'm so glad. If you look closely, you see they leave footprints and little trails of foot dust, and their speed changes as they go up and down these [dunes]." The characters in the background were simple shapes with ellipsoids for legs and feet; the foreground characters were more complex. 
Fast Mummies 
In addition to the mummy himself and the mummified Anubis warriors, the sequel brings back Imhotep's soldier mummies and introduces pygmy mummies. The soldier mummies chase the O'Connells through the streets of London; the pygmy mummies chase the O'Connells through a jungle. 
For the soldier mummies, Jeannette worked with three animators who made the mummies do unearthly things such as run quickly along the sides of walls in a crawling position. "They're really mean in this movie," Jeannette says. "I wanted them to be crawling because it's creepy, but it's a true challenge for the animators because they had to defy the laws of physics, and the mummies were moving really fast." 
In one scene, Jeannette ran the mummies over a car, crushing the roof underfoot. "It's a little bit of homage to the scene in Jumanji where the elephant crushes the car," he says, adding, "That was one of my first assignments at ILM." 
It's the pygmy mummies, though, that Berton predicts people will be talking about when they leave the theater. "They have a lot of close-up action with the major characters," he says. "They're vicious, strange looking, and really terrifying in a certain way. They're also intermittently a little funny." 
Jeannette describes them as little piranhas on feet. "They're totally mean and creepy little creatures." When pygmies are in the foreground, whether coming straight at the camera, driving swords through people, or doing other nasty things, they were always animated manually. Behind them, however, 100 more pygmies might also be flying toward the camera. To animate this small crowd of fast-moving demons, keyframe cycles were created by animators and applied to particles. Each background pygmy was assigned to a particle, and a field with various velocities drove the particles. "We've got crowd scenes everywhere in this movie," says Jeannette. 
Lost Souls and Scorpion Kings 
The pygmy mummies may be the most fascinating new characters, but some of the strangest crowds created for the movie were the "lost souls," thousands of writhing demons swarming inside a bottomless pit in the Scorpion King The pygmy mummies may be the most fascinating new characters, but some of the strangest crowds created for the movie were the "lost souls," thousands of writhing demons swarming inside a bottomless pit in the Scorpion King's cavern. "It keeps things lively," laughs Berton. "No one wants to step into the pit of hell." 
Perhaps the strangest new digital character of all, though, is neither mummy nor demon; it's the Scorpion King himself. In the early part of the movie, the Scorpion King is a human warrior, played by The Rock, who sells his soul in order to defeat the Egyptians. Having done so, by the end of the movie the character becomes transformed into a creature that is half-scorpion and half-human: The body of a scorpion replaces the lower half of The Rock's body. 
Creating this all-digital character meant blending the creature half with a human half that needed to look exactly like the actor. "The [scorpion half] has proven to be quite complex, with eight legs, three tails, and four claws," says Preston who describes the material it's made of as "leathery." Creating the digital human half was more difficult, however. To get a photorealistic look that would hold up in the 11 close-up shots of the digital Rock's face, the effects team used a relatively simple 3D model created from a scan of the actor with combinations of painted textures and Pixar's RenderMan shaders to emulate his skin. Painters using ILM's Viewpaint software running on SGI workstations removed shadows from photographs of The Rock's face to create neutral images that could be lit within 3D scenes. To give the model realistic skin texture, technical directors created displacement shaders; to make the skin look translucent, they wrote lighting shaders. In addition, the TDs added hair using in-house simulation tools. 
"We're working with subtle shades of skin color, translucency, markings, moles, pores, sweat, eyebrows, not with just the obvious things such as dynamic simulations and hair renders. It's a continuously evolving technology," says Berton. 
"If you have the eyelashes wrong, it doesn't look like him," explains Preston. "If we match the hairline but the shape of the hair is different, it changes his look. When his performance changes, it changes the lighting and causes shadows to fall across his face, and that changes his look. [The process is] going to go on until the last day." 
To show Sommers the complex choreography in shots of the creature waging war with the movie's protagonists, Jeannette asked his lead animator to create detailed animatics for all 35 shots. It's the facial animation that was the most taxing, though. The Rock speaks only one line-in Egyptian-but without facial expressions, his photorealistic face would not look believable. "If you don't get the expressions pretty close, you get The Rock's cousin or the brother of The Rock," says Preston. 
Back to Nature 
Character creation and animation weren't the only effects created at ILM for the movie. The film is filled with effects such as mummies exploding into small sandstorms when their heads are chopped off, mummies sucking face to steal souls, mummies leaping through walls, a woman disappearing into a pit of scorpions, scarabs once again crawling under people's skin, and a scorpion attack. Especially interesting, though, are the plant and water simulations. 
"One of the main characters makes a pact with a god, and in response the god makes an oasis come into being," says Ken Wesley, technical director. "The sand changes to earth, and palm trees, ferns, and grass come shooting out of the ground. They grow and fill up the desert in a matter of seconds." Wesley made that happen by writing plug-ins for RenderMan to dynamically generate models of the plants and animate their growth. First, he planted particles in Maya. Then, using RenderMan's Ri curve primitives to specify edges of fern surfaces, for example, and Ri patches to curl control vertices (CVs) that are later unfurled as a fern opens, the plug-in grew plants procedurally in the particle locations. To simulate biological diversity, he used a random number generator to shift hue, saturation, and value and to arbitrarily assign textures. To simulate wind, he shifted each plant as it grew according to wind strength and direction in its area. 
In The Mummy, Imhotep's face appears in a sandstorm; in The Mummy Returns, the face is back, this time in a wave of water trapped between canyon walls filmed to look 2000 feet tall. A deforming object in Maya was used to create this supernatural wave and hold it in place. "On top of that, we stacked layers of wave patterns generated from the fluid dynamic engine used in The Perfect Storm," says Neil Herzinger, technical director. The team used the 2D wave patterns to deform the geometry, thus adding detail to the surface. In addition, they used CG scientist John Anderson's splash water engine (see "Sea Change," pg. 38, July 2000), and Maya particle systems. "We used every trick we had on The Perfect Storm and added some new things," says Herzinger, who was on the effects crew for that film. New in the water rendered for The Mummy Returns is a raytracing pass created with Avid's Softimage Mental Ray and then fed through RenderMan that gave the tropical water translucency and refraction. Imhotep's face was created from a model animated in Softimage that deformed the wave with tools similar to those that deformed the water with 2D wave patterns. 
In The Mummy, the face in the sand chases the heroes in a biplane; in The Mummy Returns, Sommers brought the gag back only this time, he put the heroes in a Rube Goldberg type of dirigible, often CG, that was made from an old fishing boat, a jet engine, and a balloon. 
"When you create a sequel like this, you start with what you had in the first film that people loved," says Berton, "and then you give them something more. I think the most interesting thing about this film has been the vast amount of different kinds of effects we were faced with doing here." 
"Every day we're finaling shots and I can't believe I'm doing this," says Sommers. "I couldn't be more excited. I was allowed to make the movie I wanted to make since I was 12 years old." 
Barbara Robertson is Senior Editor, West Coast for Computer Graphics World.

Computer Graphics World May, 2001
Author(s) :   Barbara Robertson

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