it looked something like this.

It eventually started looking

like a pretty impressive 2D film.

But then the animators went one step further

to create a film that looked like this.

Suddenly the characters looked three-dimensional.

But unlike most animated movies these days,

the characters in "Klaus" aren't CGI

and can't even be considered 3D.

It's all just a trick of the light.

About 300 people, including 40 animators,

worked on the movie "Klaus,"

which took over two years to make.

And it was completed under the wire,

just one month before it premiered on Netflix.

So, why did it take so many people and so much time?

To understand, we have to go back to 2010,

long before "Klaus" was nominated for an Academy Award,

to when director Sergio Pablos came up with the idea.

Because his story was about the origin of Santa Claus,

it appealed to nostalgia.

And he thought a nostalgic, 2D animation style

like we saw in the '90s Disney films

would be a better fit for the story.

But he also wanted to advance the look,

so his team at SPA Studios in Madrid

added a few new crucial steps to the animation process.

Sergio Pablos: I never looked at 3D as an evolution of 2D.

I looked at it as a split,

like there's a new way of making animation now.

Narrator: First, they storyboarded the script

and made a cut using temporary voices for the characters.

They swapped these out later

once the real cast was recorded.

The next step was layout,

where the team designed backgrounds

and figured out the placement of the cameras.

Animating the characters and coloring the backgrounds

happened simultaneously.

The end goal was to have both blend together seamlessly

and look like they're part of the same world.

The characters were all hand drawn using digital tablets

and a program called Harmony by Toon Boom.

The animators used live-action reference videos

of themselves as a guide.

The initial sketches were very rough,

as you can see here.

But there was a cleanup stage

in which artists refined the drawings

with crisp, bold lines.

Then they painted the characters with basic flat colors.

Here, everything still looks very 2D,

but they will soon bring the characters to life

with a very important addition

usually reserved for 3D animation:

lighting.

His team tested out a new method

of lighting 2D characters

and released a two-minute, 30-second-long

proof-of-concept teaser back in 2015.

The proof of concept looked good

and secured them a deal with Netflix,

but the process was too labor intensive.

So they partnered with a French company

called Les Films du Poisson Rouge

to help advance the technology,

which they called KLaS, short for Klaus Light and Shadow.

Poisson Rouge was able to make the tool much more efficient

and easier for the artists to work with.

The KLaS tool allows the artists to paint with light

using a number of different types of lighting

in various combinations,

like "key light" and "ambient light."

With 3D CGI, light is added automatically to objects,

but it's trickier with 2D.

Pablos: Well, with the lines, with drawings,

the computer needs a certain level of AI

to even understand that this line corresponds to this line

and this hand is also this hand.

Narrator: The software tracks movement of the characters

so the light and shadows will move with it.

The program takes a very educated guess,

but it's not 100

so the artists can go in and fine-tune it by hand.

Painting with light allowed the artists

to get creative with details

down to the tiniest reflections in their eyes,

as you can see here.

The team used lighting not only to make the characters

feel more real,

but also to help tell the story.

For example, when Jesper is handing out papers to the kids

like a drug dealer,

he's always standing in the dark

to illustrate his shady behavior.

And when he's exposed at the end of the film by his father,

he's the only one standing in the light,

while the others are in the dark.

Inspiration for detailed lighting techniques

came from movies and TV shows,

like using just a sliver of light to illuminate a character

similar to this scene in "Apocalypse Now."

And this scene, when Jesper confronts the bully,

was inspired by "Breaking Bad."

It's important that the backgrounds

also look three-dimensional

and follow the same lighting pattern as the characters,

so they used "color keys" as a guide.

Pablos: They're quick doodles, you know,

they don't have a lot of detail,

but they tell you exactly what the light direction is

and how it's gonna affect both characters and backgrounds.

Narrator: For example, this color keys shows

how Jesper and Alva will be backlit

by the sun coming through the window.

And this one shows a progression of how the light

will change on Alva as she steps towards Jesper.

To make the backgrounds pop

and appear 3D like the characters,

the animators used several different techniques,

such as multiplanes, where you have layers on top of layers

to give the illusion of depth.

The team created a total of 3,160 scenic layouts

for the movie.

After they'd merged the characters with the backgrounds,

they used a second major step

that really gave the 3D characters

that intricate detail to bring them to life:

texture.

With another tracking tool,

they used contour, lighting, and motion

to add various effects to specific parts of a character.

Pablos: So now you could say, well,

I don't want a lot of roughness on the skin,

but I want the coat to feel rougher.

Narrator: For example, they can make them look

like an oil painting or a watercolor.

These textures are subtle,

but if you look closely, you can notice the difference.

In the end, the characters looked much more 3D

and like a part of their environment,

as opposed to looking like stickers

on top of an elaborate painting.

Pablos: And that's what throws people off

when they say, "This is 3D,"

because it's volume and it's moving and it has texture.

But it's really a combination of the light

and the texture that makes that illusion.

Narrator: The final stage is final composition,

in which any last-minute details are added to the image,

like particles.

While the majority of the film followed the 2D process,

the animators did use 3D models

for some characters and objects

and combined the two seamlessly.

And even though these were created using CGI,

they were lit the same way as the 2D characters were:

by hand.

Pablos: There's things that benefit from being drawn

because they feel more organic,

and there's, you know,

things that are not supposed to look organic.

There's things that are supposed to look solid,

like wagons and doors and props,

and it's really hard to make it feel consistent

and solid through drawing.

Narrator: If you look closely, Jesper's wagon is 3D,

and so are some of the reindeer.

Pablos: Whenever the reindeers had to do something,

it was particularly challenging for 3D

to look right with the 2D.

We just animate the reindeers in 2D,

and sometimes we would animate one reindeer in 2D

and the rest in the shot in 3D.

Narrator: Scenes like this chase scene

at the end of the film

so seamlessly combine 2D and 3D elements

that it can be difficult to tell which is which.

Pablos: There was a shot where Jesper

lifts a plate cover at one point,

and I commented on how good the integration

of that 3D plate cover looked with the 2D actor,

and they said, "Oh, no, no, that's actually 2D,

we just painted it to look like metal."