As people, we understand instinctively what flowing hair looks like. Or the way layers of clothes move on someone's body, or how water would splash when a bear runs through it. If it looks unnatural, our brains know -- and get distracted by it.
These are some of the technical challenges Pixar faced when making the studio's 13th feature, "Brave," which was directed by Mark Andrews and Brenda Chapman, and which opens June 22: If the technology behind its animation doesn't ring true, the audience may lose focus on the most important thing of all: the movie's narrative.
"The hope is that when the audience watches the film, all they immerse themselves in is the story, and the adventure," said Claudia Chung, the simulation supervisor on "Brave." "We know as humans walking around with clothes and hair, we know how clothes should move, and we have this sense when it actually doesn't move right. When it looks strange, a little bit floaty or weird, the audience can pop out of the story. They say, 'Why is that skirt flipping up when he jumps off the horse?' That kind of thing is what we definitely don't want to happen."
For years, Pixar's animators, and their technical counterparts, have looked for ways to push the envelope of what's technologically possible in an animated film. That's been true, for example, with its lighting of the ocean and its artificial reflections off of metal in "," the underwater effects it created for "Finding Nemo," the way it applied real physics to the in "Up," and the it added to the rolling and pitching of plastic bags in "Toy Story 3."
And for "Brave," Pixar's first feature with a female lead, a coming of age tale set in ancient Scotland, there was no less of a thirst to ensure that new ground was being broken. Pixar even developed entirely new hair simulation software -- known as Taz, after the famous cartoon character, the Tasmanian Devil -- for the movie, technology which surpassed the tools it had used on countless films dating back at least to "Monsters, Inc.," and even to "Toy Story 2."
Fur and hair
According to Steve May, Pixar's chief technology officer, and a supervising technical director on "Brave," the two biggest challenges the animation and technical teams faced in making the new movie were main character Merida's long, curly red locks, and the fur of several bears that are vital to the story.
May explained to CNET that using the new tools at their disposal allowed Pixar's animators to bring a new level of authenticity to the way Merida's hair behaves when she moves. "Merida has curly, long, and expressive hair," May said. "It's important, and a reflection of her character."
The problem, he explained, is that previous software wasn't up to the task of making her hair seem right. Done wrong, he said, simulated curly hair either wants to unravel, failing to hold its shape, or stays so stiff that it looks like it's had gel added. The goal was to make the hair soft and curly, and for each curl to bounce properly as she moves around or interact the right way when her hair rubs against things.
The new software took a significant amount of work, May said, and allowed Pixar to make both hair and fur that wasn't considered likely to pull audiences away from the story. But doing so itself took more than a year, Chung said. And before they were able to fine-tune the software to solve the problem, there were endless days of watching Merida's curly hair explode, or of watching the fur on Angus, Merida's horse, fly off as he ran around.
Another big challenge was the many layers of clothing worn by Fergus, Merida's father. A Scottish king, Fergus' attire consisted of as many as eight layers, including several of cloth, chainmail, leather, brigandines, straps, and weaponry. Plus a cloak with fur sewn on. Chung said that Pixar -- and likely no other studio either -- had never tried creating something that complicated before. And either all those layers would interact correctly with each other, or they wouldn't and the audience would know. "For cloth, that's as hard as it's ever gotten for Pixar," Chung said, "if not the industry."
The new software also helped the team solve additional visual problems like ensuring that when Merida ran through a river, the splashes looked correct. Or how her dress would appear to be a bit wet after being immersed in the river.
Pixar has worked hard over the years on its water simulations -- and had broken new ground with open ocean scenes in "Cars 2." But May said that the problem was different when working on river that's just 40 feet wide or so. To do so, the team "created what we call windows," May said, allowing the animators to "box off an area of water, and in that area, [to work on heavy] detail."
Those water simulations were so intense, May said, that computing the geometry of the water in those scenes could take multiple days.
But there was never any question that it was necessary, and the same goes for many of the other technical challenges on the film. And while May allows that there is still additional ground to cover in future years -- he'd like to give the animators even more control over individual strands of hair, for example -- the efforts have paid off with "Brave's" visuals.
To Chung -- and many at Pixar -- perhaps the most important task is making sure that the artistic and technical side of the studio's films stack up to the bar set by the story. And technology is finally allowing the studio to get to that point, she said. "We never compromise at Pixar to make things cheaper," she said. "The idea is that everyone is in it to make a great film and be artistic."
And that meant that again and again, the film's creators pushed its animators and technical team to rise to a new challenge -- much to their private glee.
"It was almost a joke by the end of the film," Chung said. The director would introduce "yet another [styling direction] we'd never seen before. We'd kind of roll our eyes and say, 'I guess we can do that,' but inside, we were all excited, because it's one more stretch we can do."