The hairy task of creating Rapunzel in ‘Tangled’

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When long, golden tresses are your only means of escaping a prison tower, eluding an abusive mother and rescuing the handsome thief who has promised to take you on your first road trip, a bad hair day is not an option. To ensure that Rapunzel never split an end in the new film “Tangled,” Walt Disney Animation Studios unleashed a small army of digital stylists -- a team of more than 30 animators and software engineers -- that Vidal Sassoon himself would envy.

When it comes to computer generated animation, hair is, well, hairy. Computers have trouble when objects collide, and Rapunzel’s hair is made up of more than 100,000 objects (i.e. strands) that bump into one another, sweep over her shoulders, slide across the ground and crash into other characters in moments of both embrace and defense. As character-generated animated characters go, Rapunzel is Mt. Everest, and ‘Tangled’ a sign of how high the medium has climbed since shiny, hairless toy characters populated the original ‘Toy Story’ in 1995. ‘This is a progression of the art form,’ says Jerry Beck, animation historian and editor of the site Cartoon Brew. ‘The difference with ‘Tangled’ is that the hair is a character unto itself.’

Long hair is costly in terms of computing power and technicians’ time, which is why most female CG characters wear their hair in a bob or a Lara Croft-style braid. In the case of “Tangled,” a wash-and-go ‘do was out of the question. Rapunzel’s famously magical hair had to remind the audience of the character’s vast, untapped potential.

“They tell you never to do long hair in CG because it’s one of the most difficult, most complicated things to do,’ says Byron Howard, who co-directed ‘Tangled’ with Nathan Greno. But, says Greno, ‘at its core, this movie is about a girl with 70 feet of hair, and if you can’t get that right, then you don’t have a movie.’ The filmmakers started out with a “hair bible,” a set of drawings created by Glen Keane, the artist behind some of Disney 2D animation’s greatest hair hits — Ariel from “The Little Mermaid,” the Beast from “Beauty and the Beast” and Pocahontas. Keane, who had been a director on ‘Tangled’ before Disney rebooted it in 2008, stayed on as an animation supervisor to guide the filmmakers stylistically in creating wavy, lush, shampoo commercial-worthy hair.

To understand the feeling of carrying around that mass of hair, animators donned helmets with 70 feet of fishing line attached and ran down the hallways of the animation building. To see how hair would shimmy and shake when let down from the tower, they dropped 70 feet of cloth from a balcony in their office and waved it around. They brushed wigs at their desks and asked a model with hair past her waist to perform tasks like walking stairs and tossing her head. ‘At times the animation building looked like a mental institution,’ Greno said.

It fell to a core group of 10 software engineers to figure out how to duplicate the look of real long hair in a CG environment, and their early tests weren’t encouraging. A single scene could take weeks for the computer to simulate, and when it was finished, Rapunzel’s hair might drag behind her like a long tail that the filmmakers called ‘the racetrack,’ clump into a mass or wrap around her face like Cousin Itt.

‘We developed different techniques to put in the twists and turns and hold it while it moved, which is not what hair wants to do naturally,’ says Kelly Ward, a software engineer at Disney who helped create the program, Dynamic Wires, used to animate ‘Tangled.’ ‘We had to make up physics to do it.’ (Ward isn’t kidding: The hair team includes at least one member who has a logarithm named after him.)

Computationally, blonds are especially high maintenance. Multiple colors make up blond, requiring extra delicate work by teams of lighters and shaders to keep Rapunzel’s golden locks from looking dyed and to add a high shine.

Most importantly, Rapunzel’s hair had to reflect her personality. ‘There was a performance to the hair,’ Ward said. ‘When she’s doing cartwheels, the hair had to have huge arcs to symbolize that she’s free, she’s out of the tower.’

Now that ‘Tangled’ is done, the filmmakers are free of a heavy burden too. ‘Maybe next movie,’ Howard said, ‘shorter hair.’

-- Rebecca Keegan

Twitter.com/thatrebecca

The two videos below depict a computer simulation of Rapunzel’s hair in ‘Tangled’ and the final scene.

Videos: Disney Enterprises