varjopassi

Varjopassi, literally "shadow pass" in Estonian, is a term used in computer graphics and visual effects to describe a render pass that encodes shadow information in a scene separate from the main image. In multipass rendering pipelines, the scene is rendered in multiple passes such as diffuse, specular, and ambient occlusion, plus a dedicated varjopassi. The varjopassi yields a grayscale map indicating where shadows fall and how strong they are. In compositing, this pass can be blended with the beauty pass to adjust shadow strength, softness, or location without re-rendering.

Generation and usage: Many render engines provide a shadow pass by isolating lighting contributions or using a shadow catcher. In compositing software like Nuke or After Effects, the pass is combined with color and glow passes to produce the final image. It supports non-destructive lighting tweaks, easier color matching to live action plates, and fine control of shadow edges.

Relation to other passes: The shadow pass is distinct from ambient occlusion, depth maps, or shadow maps used in real-time rendering; it specifically captures how shadows affect scene luminance from light sources. It can be used with matte extractions and shadow catcher techniques to integrate CGI shadows with other elements.

See also: Render pass, multipass rendering, compositing, shadow catcher.