If you peel back the layers of Rapunzel’s hair in Tangled, you will be able to see how complicated animating 3D hair can be. Back then, Disney mainly focused on straight hair, building on its previous 2D looks. Getting from there
to here
required over a decade of progress and innovation.
Disney’s first major foray into 3D hair animation came with “Tangled”. Rapunzel’s 70 feet of hair was a character of its own, breaking every law of motion. Every shot of the movie was bending the laws of physics; otherwise, things would have looked very flat. This emphasised a key tenet of Disney’s animated hair — the goal isn’t always to make it as realistic as possible, but rather believable within the fictional world of the story.
The animators on Rapunzel had to take everything into account while doing CG hair, even aspects like wind and different sources of light that might not be obvious on screen. Rapunzel’s strands interacted with cloth, skin, and other hair. The other characters were constantly touching, pulling, climbing, and rolling in it. Accounting for all these interactions required simulation, a way of automating the movement of elements like hair, fur, and cloth.
To accomplish this, engineers created a program called Dynamic Wires, combining physically based simulation with laws for determining the hair’s behaviour that defied physics. This allowed the artists to make Rapunzel’s hair twist and turn however they wanted. In real life, this hair would have weighed 60 to 80 pounds and would have clumped into a mass or drag on the ground, like a heavy tail. In the movie, though, the hair glided smoothly.
Disney had developed a hair-brushing tool – iGroom – for Bolt, which worked with short-haired characters. But that plus the tools from Tangled weren’t enough for Frozen’s braided looks.
So, Disney’s engineers built a new hair-grooming system called Tonic. This was a volume-based tool, which allowed the artists to group the hairs on a character’s head and move and direct sections of hair in their desired ways.
Figuring out hair’s interaction with the wintry elements in Frozen, paid off in Moana, where the focus was on hair’s interaction with more forces, like water and character movements. Both Maui and Moana had long, curly-wavy hair. Disney’s first task was sculpting their zigzag, or S-shaped, curls, a hair shape they hadn’t created before.
Making those shapes on very long hair and trying to figure out how to manage individual curl locks required Disney to expand Tonic’s tube-grooming tool, giving it the ability to curl hair. After sculpting the shape, the team figured out how the waves would move and hold their look. Part of the trick with wavy or curly hair was retaining the volume of the hair, because if they simmed it as was, it would have collapsed and fallen flat on the characters’ heads. So how did they retain the flowiness of it?
The team on Moana developed an elastic rod model, which determined the degree to which the hair would retain its twists and springiness under different forces, like wind or water. For example, if Moana was compressed, how much of her hair would bunch up?
Disney also wanted to give its animators an ability to guide the simulation of the hair. So, the engineers built Quicksilver to combine rigging and grooming controls. This let the animators put the hair into starting poses and Quicksilver’s engine could use those poses to determine the resulting movement. It was particularly useful for when the character was doing something with their hair
The characters’ darker hair also broke new grounds for Disney, who hadn’t done any black, dark hair colours, which reacted fairly differently to light as compared to other hair colours. All of these technologies and more came into play in Encanto.
The shading advancements were from Moana and Maui’s S-shaped curls. Though Disney had the software to be able to do type 1 hair and type 2 hair, but anything beyond that was not in its technological capabilities.
The technology team collaborated with the animators to figure out what hair actually did when it started to coil versus when it was wavy and then to figure out how their tools could actually do that. No two curls could look exactly the same otherwise they felt artificial. The team also had to capture the variation in the variety, size and colour of the curls and had to make sure that nothing was symmetrical.
What set Encanto apart from previous movies was also the sheer scale of its hair diversity, not just for the Madrigal family but for the entire town. Turbans, a variety of braids, little girls with an Afro. Every single head of hair had to be styled meticulously by the artists.
At the start of production, braiding was a very manual process. By the end of the movie, however, a more automatic process for making braids where artists drew or created a curve, a line along the head where they wanted the braid to come out, and a little computer-made braid would develop.
That still didn’t mean all the work was finished. There was so much diversity, even within braid types, that the animators had to figure how to make those look good as well.
Ultimately, Encanto made history as the first Disney animated movie to represent the full range of hair textures, from 1A to 4C; a milestone reached by building a foundation of tools and then adapting them.
-Stuti, DPS Noida
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