What are occlusion shadows, and how should I apply them to my artwork?

Sara Pierce, England

Answer

Bram replies

When doing detailed lighting work I’ve gotten into the habit of simplifying each step of the painting process as much as possible. Focusing my attention on one aspect at a time helps to not become overwhelmed and almost always results in a much more thorough job.

One step in that process is concentrating on occlusion shadows, which occur where surfaces come together. A basic rule of thumb is that wherever areas are closed in by surfaces, shadows will occur. The inside of a mouth or an eye socket for instance will almost always be darker than the top of the nose or the forehead. They’re a form of shadows best noticeable when there’s no directional light present. So you can paint them on a separate layer without having to worry about the direction of the overall lighting, and then set that layer to Multiply to have it distribute the shadows on the objects below. In my example however, I do have a lighting scheme in mind with directional lights and cast shadows, but these build upon the occlusion shadows rather than replacing them.