Issue: Volume: 32 Issue: 2 (Feb. 2009)

Short Subjects, Big Ideas


Short Subjects, Big Ideas
Last year, under the direction of Ed Catmull, president, and John Lasseter, chief creative officer, Disney Animation Studios and Pixar Animation Studios each released a feature and a short animated film. Whether by design or happenstance, the short films are completely different in style from the features, which themselves pushed the studios in new directions.

Disney’s Bolt (see “Back to the Future,” November 2008) is a CG film that begins with a rousing superhero action sequence, followed by a comedic road trip and coming-of-age story. Its adorable stars are a CG dog, cat, and hamster in a glass ball. On the other hand, Disney’s animated short “Glago’s Guest,” which is directed by Bolt co-director Chris Williams, is a thought-provoking film in a bold, minimalist style. It’s a far cry from what most people think of as a Disney film.

Unlike either of those films, in Pixar’s science-fiction feature Wall-e (see “Rampant Risk-Taking,” July 2008), the robot wanders through dusty, rusty CG scenes that are different from any we’ve seen before, as he collects trash on an abandoned planet and then follows his super-modern Eve to a weird and brightly colored world. But, “Presto,” Pixar’s animated short about a magician and his rabbit, set in 1912, is as wild and wacky as a Bugs Bunny, Tom and Jerry, or Tex Avery cartoon.

At one time, people seemed to think there was a CG style, that 3D animation was a genre. The films competing for various awards this year, not the least of which are the Disney and Pixar shorts, prove that CG tools do not define the art. Artists do. –Barbara Robertson
 
Simple Truths
A Russian soldier marches from his outpost into a vast expanse of snow-covered tundra every day. He guards nothing. He keeps his eye on nothing. His name is Glago, and he’s the star of Walt Disney Animation Studios’ short film “Glago’s Guest.” And yes, he does have a “guest.”

“I’m being very careful about protecting exactly what happens for those people who haven’t yet seen it,” says writer and director Chris Williams. “In the second half of the film, a bunch of aliens confront him and give him a new outlook on life. He learns that even when it seems like your life is in a rut, you never know what might happen. He has to make a judgment, and he could be wrong.”

Unlike Glago, Williams’ life wasn’t exactly in a rut. The 14-year veteran at Disney had worked as a writer for The Emperor’s New Groove and Mulan. But, he couldn’t have predicted what happened next. 

Even though Williams had not directed a film before, he found himself directing “Glago’s Guest” and co-directing the feature film Bolt simultaneously. “Glago’s Guest” has received four Annie nominations: Best Animated Short Subject, Production Design (Andy Harkness), Storyboarding (Chris Williams), and Writing (Chris Williams). Bolt has received an Oscar nomination for Best Feature Animation.

When John Lasseter took the reins at Disney Animation, he asked Williams to pitch short-film ideas. “John sees short films as a sign of vitality within a studio,” Williams says. He pitched six ideas, and of those, Lasseter picked the most unusual.
 
Director Chris Williams made his film using CG in part to create a vast emptiness that would have been more difficult to achieve with hand-drawn animation.

Because Williams had already storyboarded the film “Glago,” it moved quickly into production. But soon after, Lasseter asked him to work on Bolt. “I was excited about ‘Glago,’ and I could see the enthusiasm on the part of my crew, so I asked John if I could make both at the same time,” Williams says. “He okayed the idea, so I split my time.”

The Deep Empty
Williams had always envisioned “Glago” as a CG film. “The vast emptiness is an important element, and 3D allows you to feel the huge open space better than 2D can,” he explains. To help reinforce that feeling of empty loneliness, Williams set the story in 1920s Russia. “I’m from Canada, so I know what it’s like to be in a snowy, empty environment,” William says. “I think people sense that Russia is a huge land mass with large areas that are not heavily populated, especially back then.

Setting the film in the 1920s also limited Glago’s ability to communicate with the outside world and the weapons he’d have available. “One of the movies we watched for reference was Reds,” he says. “The whole time I was watching, I was thinking that all those characters were just one cell-phone call away from solving everything.”

As for the aliens, Williams wanted Glago to confront something outrageous, something he’d have to judge. “The first drawing I did had Glago with a typical alien that had tentacles and a bunch of eyes,” he recalls. “But I tried to come up with something more interesting than that. I pared things away until I was down to a minimal form.”

Many of those minimal forms, an orb, became the aliens now in the film. “I hadn’t seen aliens look like that before,” Williams says. “Also, because they’re simple, blank, and faceless, Glago can project onto them intentions that might not be true.”

The aliens became the second motivation for creating the film in CG. “One of the great things about CG is that it allows many creatures on screen moving in sync,” Williams says. “We could give them a strangely unnerving quality that creates an interesting impression on the audience. That’s something we couldn’t pull off in 2D, and maybe not even in live action.”

Darin Hollings, who came to Disney Feature Animation by way of the visual effects studio DreamQuest Images and Disney’s The Secret Lab, supervised “Glago’s” visual effects. At Pixar, short films are often a springboard for talent and a testing ground for technical innovation, and Ed Catmull, Pixar’s founder and now president of Pixar and Disney Animation, carried that tradition to Disney.

“Ed Catmull and Andrew Millstein [executive vice president and general manager of Disney Animation] wanted us to try innovative things with the short,” Hollings says. “So, we created a new pipeline from scratch. We wrote new tools to manage all the assets, and a new lighting package to send everything to [Pixar’s] RenderMan. Our goal was to get the highest quality level with the least amount of artist time as we could. We wanted to make things fast throughout the pipeline so when animators opened a scene, they could scrub the animation. They didn’t have to do a playback.”

Pushing Pipeline Speed
Although the crew based the pipeline on Autodesk’s Maya, they designed it to be independent. “All the metadata, the way we put shots together, and the way we lit shots was independent,” Hollings says. “The geometry stood on its own, and you could light a scene without opening Maya. Because the metadata holds the scenes together, the pipeline is agnostic. However, everything comes back to Maya.”
 
Disney’s proprietary XGen software grew hair inside tufts modeled with geometry to create the art-directed look of Glago’s beard.

Yun-Chen Sung, who had worked on a lighting package for DreamWorks’ Shark Tale, created new lighting tools called Lilo for “Glago.” Using Lilo, the artists would position lights in Maya, but they would adjust values, assign materials, and launch renders from Lilo. “Its base function is to create and manage the render passes,” explains Hollings.

Lighters used such standard techniques as subsurface scattering, ambient occlusion, and so forth for Glago, the aliens, and the snowy world. “Chris wanted big expanses of emptiness, with sky, snow, and a dark figure, especially in the first part, photoreal in a contrasty way,” Hollings says. “But, when  you get close, he wanted lots of detail and lushness.”

With the streamlined pipeline in mind, Sung made sure Lilo could produce quick renders. “We didn’t use AOVs,” Hollings says, referring to RenderMan’s arbitrary output variables, used to separate images by such attributes as diffuse, specular, reflections, ambient, and shadows. While that provides control over individual layers, this multipass technique creates extra steps in the production pipeline.

“We created efficient RIB files and did Glago on one level, the spaceship on another level, and so forth,” Hollings explains. “We did old-school levels in compositing. It made it really fast to work on a shot. Toward the end of production, I could check out a shot, change the lighting, composite it, and put it in the queue in a couple of minutes.”

Helping make that possible was the crew’s attention to speed throughout the process by creating lightweight models, textures, and rigs. “We had one super-light rig for the animators that didn’t show every deformation, and then a second rig with all the deformations that animators could choose to use or not use,” Hollings says.

For facial animation, senior modeler Hiroki Itokazu created a rig based on blendshapes. “We wanted the animation of Glago to be subtle and different from animation done in the past, so it was important to make sure the facial controls could convey that,” Hollings says. “We thought about going with a next-generation deformation slider approach, but Hiroki had already set up a series of shapes and a user interface, and had the whole thing working without even being asked.”

Simulation
To create Glago’s hair, beard, and moustache, the crew pioneered the use of Disney’s XGen software with geometrically sculpted hair. “Hiroki modeled every tuft so it could be art-directed,” Hollings says. “He sculpted the tufts, and then Mitch Snarey grew the hair to fill the volumes. I think that’s the first time we’ve constrained hair into volumes here.”
 
A new lighting package called Lilo, developed for “Glago’s Guest,” helped the lighting artists produce the film’s stylistic photoreal look quickly.

For Glago’s coat, character effects supervisor Ian Coony traveled north to Pixar to talk with the crew that handled the clothing for Ratatouille. “John [Lasseter] was over the moon about how good those clothes looked,” Hollings contends. “But, they were cotton. Glago’s coat is wool.” Ultimately, though, Coony used Disney’s Fabric in-house cloth solver for the dynamics.

“It was a fairly straightforward simulation process,” Hollings says. “Once we finaled the animation, we’d run simulations, and once the simulations looked good, we’d bake them into files.”     

The other major simulation task, controlling the little alien orbs, was less straightforward. Effects supervisor Cesar Velazquez created a process that started with particle simulations in Side Effects’ Houdini to produce the general motion of particles moving from one point to another. Then, using Houdini scripts, he created additional layers. With one, he added collision detection so the particles wouldn’t interpenetrate. Another added deformation so the little green balls would retain their volumes.

“He gave us ‘wedges’ with 1000, 2000, 5000, and 10,000 orbs,” Hollings says. “The more the orbs, the slower the simulation.” Velazquez also offered Williams different choices for how the orbs moved—bouncy, slowly, treadmill-like motion, and so forth—and with the orbs moving as a group or with some orbs moving independently.

Effects animator Dave Hutchins created most of the other particle simulations—including the blowing snow, interactive snow, and objects moving inside Glago’s house—with Maya, using hardware rendering in some cases. He also added Glago’s breath to every shot in which the star appeared.

Road Testing
Each night, when the render queue lightened up, the system automatically created a simple render of all the shots. “The pipeline was completely push-based,” Hollings says. “As an animator finished, the lighter would get the new animation. If someone moved a chair in a room and I was working on the same shot, the next time I rendered it, the chair would have moved.”

The nightly auto-render served as a troubleshooting tool. “It rendered everything in a simplistic way, and also the cloth sims,” Hollings says. “It was a way to see the status of the show every day and discover anything that was broken.”

Pixar’s Mike King helped the team develop the asset management tool, which they named Nani. “That was the tool that managed all the master sets, populated the shots with elements, and created Maya files,” Hollings says. “We also took advantage of having people on the crew, who had come from many different studios, help create tools across the board. We put our heads together and thought about what we would do if we could create a pipeline any way we wanted.”

For example, iPlay, written by Sung, gave the artists the ability to look at the whole short and select what they wanted to see within a sequence. A navigation system that moved quickly within the file system made it possible for the artists working on something within a particular shot to play the shot easily. “We tried to create the most efficient pipeline possible in a small scale,” Hollings adds.

Some of the tools and techniques road-tested for “Glago’s Guest” helped power Bolt. “We transitioned from using tile-based texturing to facet-based texturing, which Bolt then used,” Hollings says. “And, some ideas are being considered by the Rapunzel leadership. Even though exact tools may not move to other shows, the ideas flow when the people join other crews. But, that wasn’t the point. The point was to explore and innovate. It isn’t often that you get the opportunity to do a show any way you want, and to succeed or fail.”

Succeed, they did. Sometimes, the biggest achievements happen way behind the scenes.

Change-O
When Pixar wanted a new short film to show with its then upcoming CG feature Wall-e, animator Doug Sweetland jumped at the opportunity. The result is a five-minute ’toon called “Presto,” a short film about a rabbit that pulls a magician out of its hat. It’s different from anything Pixar has produced in the past, and it’s the first short Pixar has produced on a rigid deadline.

“Normally, shorts are not primary projects,” Sweetland says. “When a feature needs resources, the short goes on hold. But, one of the tests with ‘Presto’ was to see if we could do the film without interruptions.” 

They did, but it took some clever tricks on the part of the production crew to make it happen. “Our original schedule had us finishing before the peak usage of labor on Wall-e occurred,” says Richard Hollander, producer. “We lost that battle and became lock-step to Wall-e. It made for a slightly terrifying ending. But, the company was going to make this short happen.”

Pixar green-lit the idea in March and, by September, had nailed the story. “Animators work on parts, never on the whole,” Sweetland points out. “Our discipline is to take a piece and make it as rich as possible. But I had been applying that discipline to the story, which is a really bad idea. I thought I wanted two sympathetic leads. I kept creating colorful, clever bits that didn’t work as a cohesive whole. Changing Presto to a classic antagonist was a huge tidal shift for me, but it was the key.”
 
Pixar developed new motion-blur techniques to create the illusion of speed without losing a cartoony look. In this shot in the fi lm, you can see blurring around the rabbit Alec’s hands and feet as the animal tries to grab the carrot, but you can always see the outline of the hands and feet.

It also fit with Sweetland’s inclination to make a film that would be more cartoony than other Pixar shorts. For inspiration and reference, he assembled a reel of Tex Avery, Tom and Jerry, and Bugs Bunny cartoons. “They all speak with basically the same vocabulary,”
says Sweet­land. “There’s an economy to the shots that’s incredible. There’s even a quote from [William] Hannah or [Joseph] Barbera that’s something like, ‘You see a cat, you see a mouse, it’s an instant setup.”

The Setup
Sweetland wanted the setup for “Presto” to be as quick and clear as in those cartoons, but, a bunny and magician aren’t natural antagonists. “We probably worked on the opening, from the time when they’re in the dressing room to when they’re on stage, more than any other shots,” he says.

To create the rivalry, Sweetland used animation and production design. In the dressing room, Presto, an elegant magician dressed in a tuxedo, frowns as he cleans the inside of a purple wizard’s hat, but smiles when he dusts his top hat. He places both hats on a table near an enormous carrot. Sitting nearby is a cage, and inside, Alec, a white rabbit, wiggles in excitement.

Presto opens the cage door and puts the purple hat on Alec. Alec reaches for the carrot. Presto pulls the struggling rabbit back by its tail. Alec runs in place and stretches its arms toward the carrot. Presto commands Alec to stay, and then magically pulls the rabbit by its ears out of the top hat. He holds the carrot in front of Alec’s face. Alec prepares to take a bite, but Presto yanks the carrot away. The rabbit will have its revenge.

On the wall behind the table, a show bill advertises “Presto and his Hat of 40 Fathoms.” Near Alec’s cage is a sign that reads “Feed Rabbit.”

“The dressing room was a little set all by itself,” says Harley Jessup, production designer. “It started as a broom closet because Presto was at the bottom of a billing, but as the story progressed, the dressing room got larger. We added cues that told about Presto’s self-importance and how the poor rabbit was just a prop.” You can see a bouquet of flowers in the background and congratulatory posters on the wall. Grease paint, makeup jars, and tonics appropriate for a 1912 performer spill across the dressing table.

Jessup had a more complicated task once Presto moved onto the stage. There, the hungry rabbit takes charge, creating wild hat tricks of its own in front of an elegantly dressed audience—at the hapless magician’s expense. The theater is huge. In one shot, Presto hangs 150 feet above the stage floor. And then falls.

Set builders created the theater and dressing room by modeling the entire 3D space and props in Autodesk’s Maya, and then moving the scene into Pixar’s proprietary Menv software. “We definitely dress to camera, but the space allowed the layout team to move the camera in unexpected ways,” Jessup says.
 
The posters on the wall of Presto’s dressing room emphasize how much he thinks of his hat and how little he considers his rabbit. Tacked to the bottom of one poster is a tiny hand-lettered note that reads, “Feed Rabbit.” But, don’t feel too sorry for Alec. He’s a magician, too.

To help speed the production, the team borrowed props from Ratatouille, which Jessup also designed. For example, the proscenium arch in the theater is from the dining room in Gusteau’s restaurant. The fan in the dressing room is from Skinner’s office, and the dressing table is a modification of Skinner’s desk. The door to the dressing room is from the bathroom just off the kitchen in Ratatouille.

The Curtain Opens
Presto himself, in fact, looks a little like the lawyer in Ratatouille. “He’s thinner and more delicate,” Jessup says. “We reworked him. But, he bears a resemblance.” And, a close observer might think the audience members were customers from Gusteau’s restaurant who stopped at home on the way to the theater to change their costumes and hairstyles.

Like the designers, supervising technical director Tony Apodaca leaned on Ratatouille for the production pipeline. “We thought, ‘Hmmmm, we have a rodent and a tall, lanky human,’” Apodaca says. “Now which show has similar technology that we might borrow?” The crew built new characters; they didn’t deform Ratatouille characters. But, they used the same pipeline for hair grooming and simulation. The modelers sculpted in Maya, and riggers worked in Pixar’s Gipetto.

“We used rigs already in development as starting points,” Apodaca says. “But we added a lot to the facial deformation to get extreme poses.” Like Looney Tunes characters, Alec can reach three times his body length. So, riggers carefully added the appropriate amount of mesh topology to keep the mesh from breaking and to have every deformation produce smooth shapes. 

To cover Alec’s skin with fur, hair groomers used Pixar’s Gopher software, a set of Pixar RenderMan, Menv, and Maya plug-ins that work together. Texture maps and UV maps attached to geometry in Maya moved through Pixar’s Slim to RenderMan, which grew hair based on parameters set in Maya for guide hairs by using maps that determined density, color, waviness, thickness, and so forth. “It’s similar to [Joe Alter’s] Shave and a Haircut,” Apodaca says, “but we need to have our own to be compatible with our animation system.”

The unique grooming techniques developed for Alec concentrated on producing feathering of the fur on the skin next to the nose, keeping the hair out of its eyes, and making sure there was no bare skin when Alec stretches its arms. “We did all that by carefully painting the maps and knowing that if extreme animation was happening, we’d need more flesh in particular parts,” Apodaca says.

For Presto, the interesting technical challenge was in the cloth simulation. Tailoring artist Christine Waggoner designed Presto’s tuxedo and costumes for the 2500 people in the audience. “Our cloth pipeline uses 2D pattern-making,” Apodaca says. “We laid everything out the way a tuxedo would be tailored to his body. Then, we made sure the inter-cloth collisions were set up properly for the coat over the vest over the pants, so they could move around and not poke through each other. That was great for a while.”

Apodaca explains that unlike Rata­touille’s characters, Presto is stationary for a long time, and then he accelerates fast and moves quickly. When that happened, the skin went through the cloth before the cloth knew what was happening, and the skin stayed on the wrong side.
 
“We had to go back and do simulations at high speeds or fix simulations after they’d been done,” Apodaca says. “It was really a question of speed. You can run a simulation at four or eight times the frame rate so the skin doesn’t move far enough to penetrate the cloth, but even then you get funny folds or little pokes, or things get snagged.” Also, cloth fix tools used in Ratatouille helped the team pin, glue, and grab pieces of the mesh in Menv to pull them into order.

The curtain was equally difficult, but for different reasons. “It’s deceptive,” Apodaca says. “In terms of tailoring, it’s as simple as you can get. It’s a big, square piece of cloth. But, it’s extremely heavy and very long, and the numerical calculations don’t appreciate all that weight.” As a result, it was difficult to get it to hang like a real curtain and fold properly when opened, a problem solved only with much iteration. Moreover, the curtain had tassels.

“We wanted it to look like gravity placed the tassels, not like someone placed them in computer graphics,” Apodaca says. “So we held the tassels above the ground, with the big ball at the top of each and all the little fringes hanging down from that, and then used cloth sim to slowly push them to the ground. The inter-fringe collisions gave each one a nice random shape. Even though they just sit there for most of the film, if we had put them in place with Maya, they would have looked mechanical.”

For the theater crowds, created with a library of mix-and-match heads, hair types, jewelry, and body shapes, the crew used the crowd animation system from Cars. Animators created such actions as clapping, head turning, and so forth, as well as a standing ovation. “We tossed them onto the characters at random,” Apodaca says. “It was a relatively old-school simulation.”

Because the initial storyboards had several shots of Presto looking into the crowds, to make it possible to render the 2500 theatergoers, the crew put higher-resolution characters in the first few rows, lower-resolution characters behind them, and then had consistent shading across the entire audience.

“As the story evolved, we had fewer shots of the crowd because it detracted from the pacing,” Apodaca says. “If we had known, we would have put less effort into them and they would have looked worse. So, it was a happy accident.”
 
The storyboard and production design sketches show the elaborate stage on which Presto performs, the size of the theater, and the number of people in the audience. Left, the spotlight shows how far Presto will fall. Right, the heavy curtain became an interesting challenge for the cloth-simulation team, as did the crowd creation and simulation.

A ’Toon Type of Motion Blur
The biggest technical innovation for the film was in how the crew handled motion blur. In 2D animation, a cone-shaped streak with speed lines indicates fast motion. Apodaca didn’t want to replicate that look, which would have given the film a 2.5D appearance, but he wanted to get the sense of cartoon motion blur.

Dana Batali, head of the PR RenderMan group, helped provide one answer: “We changed the shape of the motion blur in the shutter of RenderMan to a more triangular shape,” Apodaca explains. “It spends more time sampling at the end of the frame, the final position, than the front, so the front edge is dense and opaque, and the back edge wispy, undersampled, and transparent.”

Then, the second answer: They blended a non-motion blurred frame that had sharp edges with the new triangular motion blur streak. The result produced an image in which you could see the characters’ silhouettes, but with enough blur so when they moved, it gave the impression of speed.

“We did this only on the characters, not the background,” Apodaca says. “That’s also an homage to the way cel is done, with beautiful watercolor paintings in the background.”

Being able to create a ’toon was a joyful experience for many on the crew. “Many of us are in animation to begin with because of cartoons, but we’re never able to do them,” Sweetland says. “There was nothing better I could ever witness as a director than to see people hurl themselves at the work with unbridled abandon. I think ‘Presto’ is a really good combination of an old cartoon and a Pixar movie.”

At the end of the film, Alec gets his reward. The rabbit has replaced the hat on Presto’s poster, and a bouquet of carrots sits next to the bouquet of flowers. As for the Pixar crew? Their rewards have only just begun.

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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