A drawing has no surface normals, so it cannot be lit. That’s the whole problem — and the reason 2D animation traditionally handles light by drawing it, frame by frame, as shapes.
The workaround is to give the drawing normals it never had. A tutorial by 3D and VFX artist Swoon, circulating via 80 Level, walks through doing exactly that in After Effects using the free Normality plug-in by Stefan Minning.
The workflow
- Generate a normal map for the 2D artwork
- Precompose the layers
- Set up a point light and a rim light with Normality
- Finish with toon shading, halftones, noise and Deep Glow for a stylised look
What a normal map actually does here
A normal map encodes, per pixel, which direction the surface faces — stored as RGB, where the three channels are the X, Y and Z components of the surface normal. It’s the standard trick in 3D rendering for making a flat polygon appear to have surface detail.
Applied to a flat drawing, it’s a lie with a specific purpose: you are declaring that this region of the image faces up-and-left, that region faces right, this one faces the viewer. Once every pixel has a direction, a light can be computed against it — and the drawing gains form shadow, rim light and specular response it was never drawn with.
The consequence that matters: the lighting becomes a parameter rather than artwork. Move the light and the shading follows. Change the colour and everything re-tints coherently. Animate the light across a scene and the character is lit by it. None of that is possible when the highlights are painted in.
Background on the general technique of lighting characters in After Effects — not Swoon’s tutorial itself, but the same problem.
The hard part is the normal map, not the lighting
Setting up Normality and a couple of lights is quick. Producing a normal map that reads correctly is the craft, and it’s where this succeeds or looks like a filter.
The reason is that a normal map for a drawing has to encode an interpretation of form that the drawing only implies. A cheek is convex, an eye socket concave, a sleeve cylindrical, a collar a hard edge — and none of that is in the line art. Generating one automatically from luminance gets you an approximation that usually looks like embossed paper, because luminance in a drawing is largely local colour rather than form.
The good results come from authoring the normal map with the form in mind, which is closer to sculpting than compositing. This is the same observation we made about the Moho 1940s advertisement earlier this week: the tool is quick, and the invisible labour is in understanding what the medium is imitating.
Why it’s worth learning
It sits in genuinely useful territory between 2D and 3D. You keep the hand-drawn line and silhouette — which is why anyone chooses 2D — and gain the lighting control that makes a character sit inside an environment rather than on top of it. For animation that has to composite drawn characters into rendered or filmed backgrounds, matching the light is most of the integration problem.
Normality is free, which makes this a no-cost technique to try on existing artwork.
Related Reading
- Learn How to Set Up 3D Lighting for 2D Characters — 80 Level
- After Effects Lighting Tutorial | Easily Light your characters — Backwoods Animation Studio (YouTube)
- Tips & Tricks — Lighting With Normal Maps in AE, Cantina Creative (YouTube)
- Normality plug-in — Stefan Minning
- Create a Normal Map in AE to Relight 2D Smoke Like It’s 3D — ActionVFX
- Normal mapping — Wikipedia