In 'Up,' the new Pixar film due out Friday, the studio had to figure out how to animate the more than 10,000 interdependent balloons that hoist the main character's house aloft.
(Credit: Pixar Animation Studios)If you want to consider a difficult computational problem, try thinking of the algorithms required to animate more than 10,000 helium balloons, each with its own string, but each also interdependent on the rest, which are collectively hoisting aloft a small house.
That was the challenge the production team at Pixar faced when it set out to begin work on "Up," its tenth feature film, five years in the works, which hits theaters on Friday.
There was absolutely no way the team was going to hand-animate the balloons. Not with their numbers in five-figures, and especially not when you consider that within the cluster, every interaction between two balloons has a ripple effect: If one bumped another, the second would move, likely bumping a third, and so on. And every bit of this would need to be seen on screen.
In "Up," the story revolves around the main character, 78-year-old Carl Fredricksen, who, frustrated with his mundane life, ties the thousands of balloons to his house and sets off for adventures in South America. A small boy ends up marooned on board, and hilarity ensues.
The cluster of balloons is so central to the film's branding--it's called "Up," after all--that to promote the film, Pixar teamed up with two of the world's cluster ballooning experts for a nationwide tour involving a real-life flying armchair and dozens of huge, colorful balloons.
"You have a movie that's about a house that flies, which is a pretty far-fetched idea," said Steve May, the supervising technical director on "Up." "We all know, from kids' parties, how a bunch of balloons behave, so if we could animate balloons in a realistic way, the believability that the house could fly would sell."
For May, "Up" producer Jonas Rivera, director Pete Docter, and the many others involved in making the film, believability was key, even within the context of a story about a flying house. And while a major part of instilling that believability must come from a well-conceived and executed story and script, the animation is no less responsible for winning over potentially skeptical audiences.
Balloons, the mother of animation invention
May said that the animation department at Pixar never even considered hand-animating the balloons. But even standard computer animation wouldn't be up to the task, because of the N-squared complexity involved in the thousands of interdependent balloons. Instead, the studio's computer whizzes figured out a way to turn the problem over to a programmed physical simulator, which, employing Newtonian physics, was able to address the animation problem.
"These are relatively simple physical equations, so you program them into the computer and therefore kind of let the computer animate things for you, using those physics," said May. "So in every frame of the animation, (the computer can) literally compute the forces acting on those balloons, (so) that they're buoyant, that their strings are attached, that wind is blowing through them. And based on those forces, we can compute how the balloon should move."
This process is known as procedural animation, and is described by an algorithm or set of equations, and is in stark contrast to what is known as key frame animation, in which the animators explicitly define the movement of an object or objects in every frame.
Procedural animation has been around for some time, but May suggested that even the most difficult uses of it in the past don't come close to what Pixar had to achieve in "Up."
Pixar fans may remember the scenes in "Cars" of a stadium full of 300,000 car "fans" cheering on a high-speed race below, each of which was independently animated. That, too, was done with procedural animation, May said, since creating so many cars individually would have been a non-starter. But even that complex computation problem didn't approach the balloon cluster issue in "Up": the "Cars" scene involved no interdependent physics.
Another animation challenge for Pixar was figuring out how to handle the feathers on Kevin, an important bird character in the film.
(Credit: Pixar Animation Studios)Getting the simulator humming properly is no easy task, as one might imagine. May said it involves setting rules for how individual objects should behave, giving the computer these initial conditions, and then "let it run."
Oddly, because the simulator does indeed run with those conditions and rules and the peculiarities of physics, the animators found themselves without precise control of what would happen with the balloons--or other objects in the film animated using these techniques.
"If the (balloon cluster) is moving too slow, we increase the amount of wind, and then run the simulator again," May said. "Then maybe we turn the wind down. It's a little fun science experiment where sometimes, hopefully by the end, we're getting what we want."
Losing control of balloons
Sometimes, given the vagaries of physics and chaos theory, unexpected things happen. The computer team inputs the rules and because some of the initial conditions are random, "you get semi-random results." One of May's favorite examples is that early in the film, when the house first is hoisted aloft by the balloons, a small group of the balloons actually broke off of the main cluster.
May said that this breakaway group of balloons is actually visible--albeit very briefly--in "Up." Eagle-eyed moviegoers can see the escaped balloons in the upper right-hand side of the screen, he said.
"We didn't mean for that to happen," he said, "but (we said) 'It's cool, let's keep it.'"
Even being able to make such choices wasn't possible at the beginning of the film's production, however. May said Pixar's physical simulator, an open-source program called ODE, couldn't initially handle the complexity of modeling the behavior of more than 10,000 balloons.
"We could handle about 500 (balloons), and we knew we needed tens of thousands," he said. "We knew we needed to develop a new simulator software pipeline...to handle an order of magnitude more complex simulation."
Of course, at Pixar, adjusting to evolving computer needs on the fly is nothing new. In fact, May said the studio has done so in one form or another on many of its films. For example, he said that when the studio made "Monsters, Inc.," it had to figure out how to animate the movie's monsters' fur. Similarly, when Pixar made "Finding Nemo," the animators had to figure out how to simulate underwater scenes.
"We had to learn about (how light refracts under water), and murk and how particulates float under water," May said.
And in "Up," too, there were additional animation challenges. Among them were figuring out how to animate and render the feathers on Kevin, a bird that is a major character in the film, and how to make the cloth on (main character) Carl's clothes seem believable.
Carl's threads were "the hardest clothing we've ever had to animate here," said May, "in part because Carl's a (small) man in an oversized suit. That was another case of (using) the physical simulation, and of setting up rules for how cloth should behave. And the looser the clothing, the more it can behave badly."
Even Carl himself presented some animation difficulties, May said, because the character's head is shaped like a cube.
Even the face of Carl Fredricksen, the films main character, presented a new animation challenge. His face is presented in a cube-like shape, which represents his lifelong sense of being boxed in by soulless development. But for animators, making him smile was hard, since his mouth would have to curve around to the side.
(Credit: Pixar Animation Studios)Like many other elements in "Up," the cube-shape of Carl's face wasn't a random whim of the director. Rather, it is a story element: May explained that Carl's character is based on someone who, as a young man, was vivacious and adventurous. But as he grew older, his small house became more and more surrounded by buildings, and "it's like his world has compressed him into a square."
Thus, a cube-like face. But May said animating his facial expressions, which must fit into this cube shape, was complicated. Smiles, for example, had to come up and wrap around his cheek.
Still, for the award-winning filmmakers at Pixar, the goal is to make even the hardest animation problems look simple on the silver screen.
As producer Jonas Rivera put it, "The audience looks at (the balloon cluster) and says, 'Oh, that's pretty.' But they have no idea how much work went into it. We worked on that for over a year. (Then) the kid takes off his hat and runs his fingers through his hair. My mother will never know that took 15 people six weeks."
On June 22, Geek Gestalt will kick off Road Trip 2009. After driving more than 12,000 miles in the Pacific Northwest, the Southwest and the Southeast over the last three years, I'll be looking for the best in technology, science, military, nature, aviation and more in Colorado, Utah, Idaho, Wyoming, Montana and South and North Dakota. If you have a suggestion for someplace to visit, drop me a line. And in the meantime, join the Road Trip 2009 Facebook page and follow my Twitter feed.
CNET News reporter Daniel Terdiman takes a ride in a flying armchair. The chair is suspended underneath what is known as a balloon cluster, and the ride took place at the Emeryville, Calif., headquarters of Pixar Animation.
(Credit: Raquel Baldwin)EMERYVILLE, Calif.--You might think sitting in a flying armchair would be a blood-pumping, adrenaline-rushing, and terrifying pastime. But I'm here to tell you that it's pretty darn smooth sailing.
I know because on Friday morning, I got a chance to take a ride on, yes, a flying armchair. And while I didn't crash it into power cables or cause a major blackout like Larry Walters, aka "Lawnchair Larry", I did take some serious air.
This was a rare opportunity to take part in what I suppose is the little-known sport of cluster ballooning. Ultimately, it was part of a high-flying promotion for the forthcoming Pixar animated film "Up."
"Up" hits theaters on May 29. As IMDB puts it, "By tying thousands of balloons to his home, 78-year-old Carl Fredricksen sets out to fulfill his lifelong dream to see the wilds of South America. Right after lifting off, however, he learns he isn't alone on his journey, since Russell, a wilderness explorer 70 years his junior, has inadvertently become a stowaway on the trip."
According to Disney spokesperson Raquel Baldwin, "Up," Pixar's tenth feature film, and the first done in Disney digital 3D, included 20,622 hand-animated balloons that Fredricksen uses to hoist his house aloft. Of course, Baldwin added, researchers at Pixar discovered it would actually take several million normal-size balloons to get much lift on a house.
Still, what better way to promote such a film than to hire two world-class cluster balloonists (Troy Bradley and Jonathan Trappe) to conduct simultaneous tours around the American West and East, respectively, giving local media rides in an armchair suspended from dozens of huge, brightly colored balloons.
I arrived at Pixar's campus here at about 5:15 a.m. Friday, just as a woman named Devony Corry, a longtime commercial hot-air balloon pilot, was holding onto one of the large, helium-filled balloons. It was clipped onto and tugging insistently at a belt loop on her pants. "This is what we need for guys who wear their pants too low," she joked, adding, "I'm just afraid it's going to rip the belt loop off my pants."
The armchair is seen in the early-morning light, before being rigged up to the balloon cluster.
(Credit: Daniel Terdiman/CNET)Here in Emeryville, Bradley (who along with Richard Abruzzo, became the first two people to fly a balloon nonstop from North America to Africa) is in charge of a group of about 10 or so people who are rapidly filling the large balloons with helium and clipping them into a quickly-growing cluster.
"We're hoping we'll lose a few people for good footage," Bradley joked as I arrived.
At this point, with the sky still in its pre-dawn state, Bradley and his crew had gotten the cluster to just 13 balloons. But he said the ultimate goal was to reach between 64 and 70 balloons, which, combined, will contain about 8,000 cubic feet of helium and have about 500 pounds of lift.
For now, the 13 balloons (which quickly become 14, then 15, 16, and so on as team members clip new ones onto the cluster) are tethered to two giant helium tanks. A brown armchair rests on the ground next to the tanks, seemingly calling out to take someone skyward.
As the sky begins to take on a little color, it's clear we're going to be blessed with a spectacular day complete with what Bradley calls "absolutely awesome conditions." Read: no wind.
At the core of the cluster is a small set of 8-1/2-foot balloons, around which are being added a set of 7-footers. Later, the cluster will be filled out with a large number of 5-footers.
As she holds on to one of the 7-footers, I chat with Corry, who tells me she's been piloting hot air balloons for more than 25 years. She said she had learned about the cluster ballooning event here by reading an e-mail chain inviting qualified folks to "come out and crew."
After awhile, the cluster is getting too big to remain tethered to the helium tanks, and Bradley and a couple of helpers carefully clip it to the armchair. But because of the lift from the cluster, it's necessary to seat someone in the chair, and so a woman named Carol Bair takes the plunge. Still, the cluster of balloons is testing Bair's weight. "He (Bradley) said the chair tips forward and I don't have my seat belt on yet," Bair joked.
One by one, team members arrive from helium tanks arrayed around the amphitheater here where the event is being held, ready to help add to the girth and wild colors of the cluster. There's actually a queue, as it's faster to fill a balloon, it seems, than to clip one on to the cluster.
"I can't afford to lose any weight," Bair said. "I have to be ballast."
The balloon cluster begins to take air as it approaches completion. At its base is an armchair in which Carol Bair sits patiently.
(Credit: Daniel Terdiman/CNET)Indeed, as a couple more balloons are clipped in, Bair gives a little shout and we can see the foot of the chair begin to move around on its own: Armchairs suspended from cluster balloons clearly have a need to take to the sky.
Carol's husband, Ray Bair, is another member of Bradley's traveling team. The three of them, plus two others, have come from Albuquerque, N.M., and have hit cities like Chicago, Cincinnati, Seattle, and St. Louis with the promotional balloon cluster on their way to Pixar. Bair tells me a cluster like this is intended to look like a lightbulb, though "it's a little different every time."
As the early morning sun crested the trees near the entrance to Pixar's campus, the balloons become brightly lit and, with the sky a brilliant blue and the balloons' various colors almost glowing, it looks absolutely glorious.
"It looks like a perfect morning," Carol Bair said.
"Oh yeah," Bradley answered, "You can't ask for better."
Taking air
The plan was that at 8 a.m., the balloon team would be done and could start giving journalists rides in the flying armchair. There were a lot of other reporters who had signed up for the privilege, but none of them had gotten to Pixar at 5:15. So I got to go first (see the video below).
I sat down in the chair and several people began strapping me in, even as two people sat on the arms to keep the cluster, the chair, and me from flying away. The wind began to pick up a little, and I could feel the chair sliding around a little bit underneath me. Just then, Baldwin handed me a waiver to sign. I joked I'd sign it when the ride was over.
Finally, we were ready, and the chair began to rise. It was smooth, almost surreally so. If I hadn't known what was going on, I wouldn't have known what was going on. They let me rise up to about 30 feet in the air, and then say a few words into a small microphone attached to my shirt, since they were filming the whole thing.
In fact, because there were already a bunch of other reporters lined up to take an armchair flight, the ride lasted just a few minutes. I would have liked to go up much higher--maybe not as high as 20,000 feet, what I understand is the rig's limit, but a little higher. But oh, well. Beggars can't be choosers.
I touched down, just as quietly and smoothly as I'd taken off, and then, just like that it was over.
You can call me "Flying Armchair Daniel." Or maybe something a little catchier than that.
On June 22, Geek Gestalt will kick off Road Trip 2009. After driving more than 12,000 miles in the Pacific Northwest, the Southwest and the Southeast over the last three years, I'll be looking for the best in technology, science, military, nature, aviation and more in Colorado, Utah, Idaho, Wyoming, Montana and South and North Dakota. If you have a suggestion for someplace to visit, drop me a line. And in the meantime, join the Road Trip 2009 Facebook page and follow my Twitter feed.
As part of a promotion for its upcoming animated feature, 'Up,' Pixar has teamed with cluster balloon pilot Jonathan Trappe to send a flying armchair around the country this spring.
(Credit: Jonathan Trappe/Pixar)Coming to a sky near you: a large cluster of multicolored balloons carrying a real-world version of the flying armchair featured in Pixar's forthcoming film, "Up."
The film, Pixar's 10th animated feature, focuses on the fate of 78-year-old Carl Fredricksen, his house, and a wayward 8-year-old who happens by one day. Together, launched into the sky by a cluster of balloons tied to the roof of Fredricksen's house, the two set off on, you know, the adventure of a lifetime.
For most of us, we'll have to go to the theater to share in the skyward experience. But in 20 cities around the U.S. this spring, a lucky few will have a chance to take part in a real-world manifestation of Fredricksen's flying armchair.
That's because Pixar has teamed up with cluster ballooning expert Jonathan Trappe to fly the armchair around the United States, accompanied by "a team of FAA-certified balloon pilots."
"The armchair flights will consist of a five-story-tall cluster of colorful balloons carefully attached to the gondola," a site dedicated to the project states, "allowing Media VIP aeronauts to ascend to tethered altitudes above the city and experience the world of lighter-than-air flight in a very unique way."
Even if you can't ride the armchair itself, Pixar and Trappe are offering some people the chance to be involved as volunteers. In each of the 20 cities, teams will gather at two in the morning to set the balloons off into the sky, and the project is taking applications now.
"Cluster ballooning takes a team of volunteers, all coming together to send the system aloft," the site says. "It is awe-inspiring to see a cluster system come together in the early pre-dawn hours. To be one of the people that send one of these rare systems aloft is something many people will remember their whole lives."
Lighter-than-air pilot experience, the site cautions, or some kind of ballooning crew experience, is preferred.
I don't know about you, but I do know that I'm going to do everything I can think of to be a part of it. I wouldn't miss it for the world.
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