• Blogs
• Forums
• Tradeshows
• Partners
• White Papers
• Events

Wet and Furry Logic

Apr 1, 2006 12:30 PM, By Ellen Wolff

Blue Sky Studios Covers New Terrain

 Digital Content Producer's and Millimeter's coverage of past and present award nominees/winners

A popular gang of furry critters has returned in Blue Sky Studios' sequel to its hit movie debut, Ice Age. But in this latest adventure, Manny the woolly mammoth (voiced by Ray Romano), Sid the sloth (voiced by John Leguizamo), and Diego the sabertooth tiger (voiced by Denis Leary) have to cope with the rising water that signals the ice age is ending. In Ice Age: The Meltdown, new environments appear, including lava geysers, grass, and trees. These gave director Carlos Saldanha a chance to depict more diverse scenery than was possible in the 2002 original (which he co-directed with Blue Sky co-founder Chris Wedge.)

But placing furry animals against varied backgrounds definitely presented technical challenges for Blue Sky's 15-person R&D team, headed by VP Carl Ludwig. Ludwig, a former NASA engineer who worked on the CG milestone Tron before co-founding Blue Sky in 1987, recalls his reaction to the script for Ice Age: The Meltdown. ”We knew we had a tremendous challenge,” he says. ”We always say, ‘Let's not hold back. Let's start with a blank sheet of paper and get as many ideas down as we want.’ Then if we find areas where we have to pull back, we'll pull back. … Rob Cavaleri, who ran our effects group, did a great job of laying it all out. After that, we said, ‘Guess what? There's no way we can do all of this.’”

Fox Filmed Entertainment (which purchased Blue Sky in 1997) was committed to a spring 2006 release for Ice Age: The Meltdown. ”We knew this was a huge stretch,” remarks Ludwig. ”We'd have to do the film in half the normal time. So it became a matter of approaching problems not from a technical standpoint, but from a storytelling standpoint. How could we still get the kinds of things we wanted, but in different ways? Could we stage some things differently — without compromising the story — and reduce the amount of unique effects that needed to be created?”

The constraints imposed on Blue Sky turned out to be a classic case of necessity sparking invention, Ludwig says. ”You're forced to really make intelligent choices.”

Furry Logic

Creating convincing-looking hair and furwould be among the biggest challenges, but Ludwig thinks Blue Sky nailed it in Ice Age: The Meltdown. ”It looks like fur, it behaves and lights like fur, and it has a range of different characteristics. Manny has coarse, almost moppy fur, while Sid is mangy. This fur technique is totally different than the first Ice Age. That was almost a mapping technique, in which 2D images were wrapped or mapped onto a surface to provide material complexity. This is truly 3D fur, which uses procedural textures.”

The method involves growing millions of individual hairs using 3D vector fields to describe a variety of fur characteristics such as length, density, clumpiness, and waviness. Then a smaller set of hairs is culled as ‘rig hairs.’ Blue Sky's proprietary software controls these hairs, describing the secondary animation of the fur as well as the effects of wind, water, and gravity. During rendering, all the hairs are animated by these rig hairs.

Ludwig credits Blue Sky's Maurice Van Swaaij with developing the fur model, and says it's an area his R&D team has been interested in since they created the furry rabbit for Bunny, Wedge's 1998 Academy Award-winning short. ”We actually had a version of a fur model around the time of the first Ice Age,” Ludwig says, ”but it wasn't ready for primetime.

”The trick was to get it — and this was my part — to light properly and have it integrated into the lighting model so that all of the global illumination and shadowing was part of it. As we went deeper into the fur, all that stuff interacted properly. You can see that the shadowing is absolutely perfect — the highlights, the edges of things, and the specular values.”

Blue Sky used the technique of volumetric (voxel) rendering to achieve this precision. All the hairs were voxelized into a discreet data set that was raytraced using Blue Sky's legendary renderer. The result was a self-shadowing volumetric body that was integrated with the rest of the scene. (The Blue Sky renderer, which mimics how light behaves in the real world, is part of the company's proprietary software package, CGI Studio. It's been developed over two decades by a team led by Ludwig and computer scientist Dr. Eugene Troubetzkoy.)

Of course, this new approach to creating fur had to pass muster with director Carlos Saldanha. He had a definite idea of what these characters needed to look like, because in addition to co-directing Ice Age, he had directed the Oscar-nominated short Gone Nutty (which starred an Ice Age squirrel-like critter, Scrat). Ludwig recalls, ”One of the things that Carlos was concerned about was maintaining the characters' artistic integrity.” So Ludwig's team created a test shot that showed how the fur could look richer and be groomed more efficiently, but still be true to the characters. ”We showed Sid all combed out, and Sid looking frizzy after a shower,” he continues. ”When Carlos saw this shot, he said, ‘We'll do it!’”

Wet and Wild

Ice Age: The Meltdown also presented Blue Sky with the challenge of propagating plants, animating fields of grass, and creating exploding lava geysers and various other water effects. Whereas the first Ice Age depicted a world of sleek, solid ice fields, The Meltdown was definitely wet and wild.

”One of the things that was clear from the beginning was that this movie had a lot of effects-laden things because of the water,” Ludwig says. ”The water had to be done with an artistic sensibility that would be consistent with the look of the movie. Yet when you're doing water it has to behave properly, otherwise it doesn't read as water. So we knew we had to come up with techniques that would bridge the existing character of the water and its behavior.”

To do this, Blue Sky used a combination of its own software and RealFlow, developed by Next Limit of Madrid, Spain. RealFlow provides a set of fluid-simulation tools based on physics principles. ”We had to modify the data that RealFlow generated to some degree,” Ludwig says. ”We developed a tremendous amount of adjunct software, including special meshing tools.

”Of course, when water becomes a plot device, you have to deal with it in a different way. With pure simulation you get what you get — but that may not be what the director wants. He may want to exaggerate something — like a splash that is more character-bound than a totally simulated splash. Where that was necessary, we bridged the gap between total simulation and something that could be directed. Rob Cavaleri's effects crew deserves a lot of the credit for forging the backbone of what became the effects work. We wrote software that helped them out, but we were more in a support role. Our symbiotic relationship with production constantly shaped and refined what we did.”

”Procedural techniques are extremely powerful because simulation fills in all of the ‘dog’ work,” Ludwig observes. ”But the concept of directable simulation is really important in an artistic medium like film. The people who use these techniques need to have creative control and make procedural things behave in the way they want. If they have that control, they can do things quickly.”

A Non-Glacial Pace

Working efficiently was crucial in order to get Ice Age: The Meltdown completed on time. Given all the plants, trees, and voxel-rendered grasses, there was a significant amount of varied materials to get through Blue Sky's pipeline. ”We'd already had a good render queue system,” Ludwig notes, ”but it was totally redone and modified for this movie to make it more robust.” The Render Queue Manager allocated Blue Sky's computing resources, which included a render farm with more than 500 processors, plus any of the studio's 150 available workstations — all running 24/7.

The studio's Interactive Renderer allowed individuals to make changes in scenes, re-render, and display the results in seconds, and Ludwig believes empowering people to make decisions on a ‘local level’ was crucial. ”We realized we had to work the way we did when our studio was smaller, giving people the freedom to make suggestions,” Ludwig says. ”If there was a problem, we'd let the guys who knew the most about it jam on the solution rather than running it up the ladder. In a battlefield, you don't go to the general for everything.

”When individuals work together but have ownership of what they're doing, it's a hell of a motivator. There's only so much energy that people have, and you would like that energy to be directed towards creativity.”

A huge asset in getting The Meltdown done efficiently was a more robust production tracking and database system, which Ludwig and his team had been developing since Blue Sky's 2005 feature, Robots, (also co-directed by Wedge and Saldanha.) ”We decided to build it ourselves rather than purchase software because we could shape it the way we wanted,” he says. ”It's called Diego, after the über-tracking tiger in the film.”

Looking back on all the custom work done for Ice Age: The Meltdown, Ludwig is philosophical about the pressures they put upon themselves. ”You tend to learn more when you stretch yourself,” he says. ”I'm not suggesting mass discomfort, but I think you can be a little uncomfortable!”

Coming next for Blue Sky is a Dr. Seuss-based feature, Horton Hears a Who, directed by ex-Pixar animator Jimmy Hayward and Blue Sky's Steve Martino, the art director on Robots. While this type of film will present a different stylistic challenge for Blue Sky, the studio intends to maintain its distinctive way of working, staying far from Hollywood in its White Plains, N.Y., facility. If there's any doubt that this studio is unique, Ludwig points out the way the crew is being rewarded for its efforts on Ice Age: The Meltdown. ”Believe it or not,” he says, ”everybody's getting a month off with pay.”

© 2008 Penton Media, Inc.