Issue: Volume 34 Issue 8: (Oct/Nov 2011)

Holy Frijole

By: Barbara Robertson
Once upon a time, in a land far, far away in which there were no ogres, or at least none named Shrek, lived a kitten, named Puss, in a small orphanage. There, the young cat met another orphan, an egg named Humpty Alexander Dumpty. Puss, the devilish charmer and athlete, and Humpty, a smart schemer, completed each other. They bonded like brothers.

As children, the unlikely pair dreamed of finding some magic beans that, legends promised, would lead them to golden eggs. And, their search for the magic beans drives the story in DreamWorks Animations’ latest animated feature, Puss in Boots. Their journey through life, together and separately, brings them fame and infamy, adventures galore, and, eventually, Kitty Softpaws, the most celebrated cat burglar in European folklore. But, it’s more than a search for gold.

At top, the star of his own film, Puss in Boots, takes a swig of his favorite
refreshment. At bottom, Humpty, Kitty, and Puss, sometime partners-in-adventure,
are the three main characters in the animated feature.

“It’s an original story and a very epic tale about how Puss got his boots and became the cat we all know,” says director Chris Miller, who previously directed Shrek the Third. “It’s hilarious. But it’s also dramatic at its core. It’s a story of redemption and brotherhood.”

Antonio Banderas voices Puss, as he did for the same character in the Shrek films, and Zach Galifianakis voices Humpty. Salma Hayek is Kitty. “We usually record the voice actors separately because these films are made over such a long period of time,” Miller says. “It’s difficult to get the actors in the same town at the same time. But, it did happen with Antonio and Salma for one session. Even apart they had great chemistry, but when they could play off each other, it was great.”

Miller began working on the film in January 2008, immediately after Shrek 3. The opportunity came as a surprise. “It was when we were doing a promotion for Shrek 3,” Miller recalls. “Jeffrey [Katzenberg, DreamWorks CEO] said to Antonio, ‘Chris is directing Puss.’ Then he asked me, ‘Can you pitch it out to Antonio? He’s really excited.’ I told him, ‘OK, but I have no idea what the story is.’ He said, ‘Call someone.’ ”

The idea of spinning Puss in Boots out of the Shrek series and into a film of his own had been bumping around the studio for several years, but until Katzenberg told Miller he was directing it, Miller didn’t know the studio had moved the project forward. “After Shrek 3, the studio saw a script that had potential and committed to it,” Miller says. “When I learned I was directing it, I took a pass at that script. They greenlit it. And then, they brought in a real writer.”
The story takes place before Puss meets Shrek, and stars, in addition to the three main characters, two murderous outlaws called Jack (Billy Bob Thornton) and Jill (Amy Sedaris). Also, as was true for Shrek, other familiar fairy-tale characters make an appearance. “All new,” Miller says, “none of the same characters we saw in Shrek.”

At top, animators who performed Puss and Kitty needed to create quiet moments
filled with intense facial expressions. At bottom, Humpty, on the other hand,
called for a broader style of animation.

Here Kitty, Kitty

To organize the work on the show and distribute it among the 60 or so animators, Miller assigned lead supervisors to specific characters. “I think it made things a little complicated,” he says, “because things came in pieces from a dozen sequences at a time. But I think it was so worthwhile because we had such great consistency within sequences.”

When two characters interacted in complex shots, two animators worked on the shot, but usually the person whose character was most prominent in the shot created the entire thing, including the other characters.

“It wasn’t an easy film to animate,” Miller says. “When you have a strongly caricatured character with broad animation, it’s easy to zero in on that. The characters are not photoreal, but they aren’t hyper-caricatured either.”

Thus, the animators who had most recently been working on How to Train Your Dragon and Megamind, both of which had broad animation styles, needed time to adjust. “It takes a little while to shake that style out of your system,” Miller says. “The approach on Puss is so different. It’s quieter. When it is broad, it is for effect. Kitty was the same way. Their movements are subtle, and they are quiet a lot of the time, acting only with facial expressions. It didn’t take the animators long to adjust, but I think when they got a Humpty shot, they were probably excited. They could loosen up a bit.”

With Humpty, the animators could have fun with the way he moved, the physical comedy. Humpty’s challenge was that he couldn’t look like a guy in a suit with a rubber mask; his face needed to feel hard.

“He’s a character who is all face,” says Nathan Loofbourrow, character TD supervisor. “There’s a lot going on in his head, and you can read everything on his face. But, he couldn’t feel like a human face talking through an egg.”

The character TDs, modelers, and animators spent approximately a year and a quarter in look development before they found the right combination of movement and expressions. “We’d tread a careful line in terms of rigging and look,” Loofbourrow says. “If we made him look too much like an eggshell, you wouldn’t expect him to move and stretch. But, if we made him too fleshy, he looked like a creepy bald person. So, we’d aim down the middle until we’d get a big grin with his eyes popped open that felt right. Humpty isn’t the hero. But, if he doesn’t hold up his end, the movie falls apart.”

And all the king’s horses and all the king’s men couldn’t put the movie together again? “He keeps the quiet drumbeat going,” Loofbourrow says.

Kitty, on the other hand, takes her cues and her rigging from Puss. “She complements him,” Loofbourrow says. “We used roughly the same rig, but female leads are always hard—and Kitty was no exception. We wanted her to be intelligent and attractive, but she couldn’t dominate Puss. And the cats could never feel little, like they could be crushed by humans.”

Character TDs needed to rig Humpty’s face so that,
on one hand, it didn’t look like the egg would crack
when he smiled, and on the other, it would look rubbery.


Many of the humans live in San Ricardo, Puss’s home village, which has 120 residents—including some thieves who hang out in the bar. The small number of crowd characters allowed the teams to make more interesting characters than the typical generic humans. “We wanted craggy, interesting faces, like in a Sergio Leone film,” Loofbourrow says. “I think of them as having ‘half-hero’ faces. We didn’t put the same amount of time we’d put into a hero, but we made unique characters.”

The differences were primarily in the faces, as Loofbourrow mentions, and in their costumes. For cloth simulation, the crew used a combination of in-house tools and off-the-shelf software. “We can warp clothing so that it looks like it moves, but for the most part, we simulated the cloth,” says Ken Bielenberg, visual effects supervisor.

All told, the team created approximately 30 different types of men, 20 women, and 12 children. By modifying hairstyles, eye color, and costumes, the designers could easily create a catalog of thousands. “The art department wanted to specifically pick out the ones they wanted to feature, though,” Loofbourrow says. “We made some choices about how to model the faces and bodies so we could adopt new faces and quickly apply the rig and do touch-ups to adjust the faces.”

Although Puss was a character in Shrek 2, Shrek the Third, and Shrek Forever After, the character TDs did not reprise his two-year-old rig for his starring role. “Animators need to give a hero character a more expressive performance,” Loofbourrow says. “They ask for subtle things, for extra levels of controls.”

Puss also spent time in the grooming salon getting a hair transplant. “He has more hair than before, and layers of dynamic performance, so the fur responds better to his movement,” Loofbourrow says. “He has little tufts of hair on his elbows and in his ears, neck fur, and other little stuff that makes a richer look.”

The character TDs added controls to the rig for areas that the animators needed to see move or wanted to move themselves—the whiskers, for example; otherwise, the character effects department handled the dynamics.

“We used some of our traditional fur smooshing techniques that we developed way back for Shrek,” says Bielenberg. “But for this film, the effects department developed a [Side Effects] Houdini-based pipeline to do the hero fur smooshing. The great part about that was they could do four or five different types of sims together.”

One simulation might cause the fur to smoosh and avoid Puss’s belt or boots. Another might add wind. A third would move select parts of the fur a little more than others. A fourth would wet the fur. And so forth.

“Before, we had to do the simulations serially,” Bielenberg says, “one, and then the next. With Houdini, we could do all the sims together. Also, we could view all the guide curves in Houdini, so the effects artists could see the volume of curves and push any we needed to fix by using deformations to move them into position.” Before, they deformed the curves by using texture maps and fields, which meant they worked blind; the artists couldn’t see the result while they worked.

“We still have to spend time doing technical steps, but we’re definitely getting to the point where we can focus more strongly on the creative iterations,” Bielenberg says. The reason is that hardware is faster, and software is better. The next-generation tools also allowed more complex models.

 Creating Cloud World

“From the effects point of view, our biggest challenge was the cloud world,” says Ken Bielenberg, visual effects supervisor. “In the past, we typically used matte paintings for clouds unless we wanted more dynamic stereo 3D clouds. But the systems we developed for 3D clouds were difficult to use, the data was too large, and they were unwieldy. So, we ended up doing only a handful of shots. On this film, we did around 40 shots with volumetric clouds, and they worked out really well. Brett Miller, our effects lead, was instrumental in making that possible.”

Miller spent a year and a half leading that effort, which relied almost entirely on in-house tools: a simulator called Flux, volume modeling tools that sit inside Side Effects Software’s Houdini as a plug-in system, a new sparse volume format, and volumetric shaders.

Puss, Humpty, and Kitty run around on top of clouds shaped like hills in a pastoral English countryside or maybe the South of France. In the distance, some clouds have shapes like trees. “We see fluffy stuff swirling around, as if they were on a stage with dry ice,” Miller says. “The clouds close to where they stand are packed and sculptural; they react to their movement. Initially, we wanted to create clouds with a photoreal look, but because the clouds represent childhood dreams, the color palette shifted from whites and blues to pinks, oranges, and gold. They look a little stylized and cartoonish.”

Modelers created the cloud shapes, and then the effects artists converted the shapes into particle-level sets. “Once we had the volumes modeled, we could take pieces and run them through Flux, our gas simulator,” Miller says. “By sim’ing part of a cloud, we could give the impression that it’s moving, without changing the look.”

Flux, which sits inside Houdini, works solely with voxel grids; voxel grids are the only inputs. “So, it’s really flexible,” Miller says. “If you want a new force field, you create a voxel grid. You don’t have to write a plug-in to do a field. Emitters are voxel grids. Fields, collisions, everything.”

Everything, including characters. “We knew we couldn’t take a character and replace it with a hierarchy of articulated rigid bodies to do the collisions,” Miller says. “We really wanted deformations to push the clouds around. So we converted our character meshes into level sets and used those level sets to mask off velocities in the gas simulator, which gave the impression of collisions. Ron Henderson [R&D manager] had the idea of using voxelized data as the collision object. Rather than using a thin shell mesh, we were using the entire interior of the character.”

To add complexity in the motion, the artists sometimes added small collision blobs only to cause movement in the fluid; they didn’t render the blobs. “It was a steep learning curve for people coming from [Autodesk] Maya, where they dropped tools into a voxel grid,” Miller says. “Flux makes complex things simple, but it takes the same amount of work to make simple things. We’re still figuring out the best way to use it to do simple things.”

Using a sparse volume format that R&D effects engineer Ken Museph wrote, the volumes could be huge. “One shot had a volumetric grid that was 900 by 500 by 15,000,” Miller says. “But the format managed it really well. We couldn’t have done this without it.”

Also helping to manage the huge area were new methods for speeding rendering with the sparse format. “We do a lot of work with frustum buffers,” Miller says. “With these big cloudscapes, we have a continuous level of detail, and some were miles deep.”

To solve a typical problem with frustum buffers—that is, shadow issues created when panning the camera—global effects developer Devon Penny wrote a system in which it was possible to rasterize a simple orthographic buffer in addition to the frustum buffer. “The coarse buffer was never visible in the camera frustum,” Miller says. “But it handled all the shadows outside the frustum buffer. It was very helpful.” –Barbara Robertson

Desert Life

“That was my challenge to the modeling supervisors at the beginning,” Bielenberg says. “I told them to push the complexity of the models beyond what we had done before. My take on this is that we were holding back based on older practices of having to save disk space and being careful about lighting and rendering. We still have to be smart, but I believed we were holding back too much. The process could handle more complexity in our models and environments, especially for buildings and towns. It ended up being fine for lighting.”

Puss himself was the touchstone for the environments. He is a walking, talking cat. But even so, he’s somewhat realistic, and the environment needed to be one in which he could exist. “We had a fair amount of realism,” Bielenberg says. “But we pushed it more than we did for Shrek. If something was organic, we made it more organic. If it was lush, we made it more lush and saturated. Puss is in a Spanish world, and we wanted to get the passion of Spain into our visuals. We strove to make the overall look vibrant and rich color-wise and shape-wise.”

After Puss leaves San Ricardo to escape from authorities (someone tricked him); to search for those magic beans, his journey takes him through various desert landscapes. To create these landscapes, the art department designed and built a rough model of a generic desert. Layout artists scouted locations in that desert and sent them to modeling for hero surfacing. “We went to cards and sprites in a few places, and in the foreground, sometimes we dressed the sets with hero high-resolution bushes, shrubs, and yucca plants,” Bielenberg says. “But, for the most part, with the faster machines we have now and more storage, we could push through a large amount of geometry, so we didn’t need to do much level of detail with the environments.”

Richard Daskas, Dominique Louis, and Christian Schellewald created a digital painting of the
growing beanstalk, which the CG department would later re-create.

The modelers took Bielenberg’s challenge to build complex models too far, though, with an unlikely object: a tumbleweed. “We put way too much detail in it and hadn’t tested rendering before we scattered hundreds in the desert,” Bielenberg says. “It was probably the single most complex thing we tried to render.

The branching structure was complex and it had too many thorns. We had made complex buildings, but this silly plant killed us. We learned our lesson and fixed it.”

One of the big action scenes in the movie takes place in the desert as two carriages race through a desert canyon. “We had a lot of trailing dust next to cliff edges and spewing rocks,” Bielenberg says. The effects artists sent rocks off the cliff using a mixture of Autodesk’s Maya and Side Effects Software’s Houdini. “During the course of Puss in Boots, we used Houdini so much that we ended up working out a site license with Side Effects,” Bielenberg says. “It’s definitely part of our core set of tools.”

 Stereo Clouds

“We wanted to make a stereo 3D movie that was worth seeing in the theater,” says director Chris Miller. “People pay a premium to see a stereo 3D movie, and we wanted to create an experience that you have to see in the theater.”

The beanstalk growing into the cloud world offered one of those experiences. “To be on the ride with the characters when the beanstalk takes off like a NASA rocket is explosive at first,” Miller says. “Then we settle in for a romantic ride in the cloud layer. Then, we go through a torrential thunderstorm for a beat. Then, we’re on the edge of the atmosphere. It’s ethereal, dreamy. We see the aurora borealis. The stars turn into snow, and we have a whiteout. It’s breathtaking. We have so many other opportunities, too.”

Miller cites a scene in which the characters ride back to earth from the clouds. “They don’t go down the same way they went up,” he says. “It’s exhilarating.” –Barbara Robertson

A Growing Concern

The largest environment, though, and the largest effects sequence happens when Puss, Humpty, and Kitty plant the magic beans. A giant tornado created with particle and fluid simulations drops down from the sky and drills into the ground. There, a beanstalk explodes from the ground like a rocket and climbs up into the clouds (see “Creating Cloud World,” pg. 14).

To grow the beanstalk, the effects, modeling, and layout departments had to break from the typical workflow by which models move through the pipeline. “We grew the beanstalk procedurally, so we had UV issues, texture stretching issues, and we needed to do more procedural textures,” Bielenberg says. “And, we couldn’t give rough models to layout. We grew the beanstalk and handed it to layout. They blocked in a camera. We made the beanstalk look better. They adjusted the camera. It was an iterative loop; not our normal path. But by participating in the camera process, we could help work out the best way to utilize the stereo aspect. We’re always looking for story-driven stereo moments for our films, and the beanstalk was one of those sequences.”

Puss, Humpty, and Kitty climb the plant up through the clouds to a giant’s castle, and inside the castle, the characters find themselves in a jungle, and then in a moat. Both sequences landed in effects late in the process. “Suddenly, we had to create our version of an Avatar moment with a complex and giant jungle, and then we had a water sequence,” Bielenberg says. “We used our ocean height-field system to generate waves for the water, particle simulations to create individual splashes, and fluid simulations for foam.”

During the sequences, the characters find themselves swirling in a whirlpool within the moat. The challenge for the effects and animation artists was to match speeds for the two elements—characters and water. “We did some initial simulations and put in some red spheres for markers to show the intended speed of the flow, and sent that to animation,” Bielenberg says. “Invariably, though, the animators wanted the characters to go slower or faster than the water, so we iterated until we got that right. Maintaining the right sense of drama and urgency with the speed of the characters and the water was very important. The whirlpool, the dust, the jungle, and the clouds were our biggest effects challenges.”

Among them, the clouds were the most difficult. “Creating the cloud world was an extraordinary challenge,” says Brett Miller, effects lead. “They have incredible depth and texture. You can enjoy them in 2D, but they’re really great in 3D. The clouds were something that executive producer Guillermo del Toro really pushed us on. He saw that the cloud world was surreal, and he said, ‘If you are going to do it, go all the way. Push the envelope.’”

Jack and Jill are the two main human characters, but Puss’s home town has many more, all
created with “half-hero” facial rigs.

Chris Miller pitched the film to del Toro, who had directed the award-winning, live-action feature Pan’s Labyrinth, during del Toro’s visit to DreamWorks early in production. “He came to a screening and loved the movie,” Miller notes. “He said he wanted to be part of it, and by the next afternoon, he was the executive producer. He would come in once a month and we would show him everything. He had great insight into all aspects of the film.”

Often, DreamWorks’ animated features have two directors, so for Miller, who was the sole director on Puss, having del Toro available was especially exciting. “It was great to have a guardian angel to talk to who could champion the film,” Miller says. “By the time the third Shrek had come around, that world was settled into its ways, so this film felt like my first one. It was liberating.”

Once upon a time, as the making of Puss in Boots’ story goes, there was a simple movie, a spin-off that people could easily dismiss. But it grew and it grew, and became a bold, colorful, complex film. “We took our lead from Puss,” Miller says. “Everything is a reflection of who he is.”  

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

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