Design Nomenclature / Light & Optics
Core shadow
Also called core, shadow core, crest shadow
- Light & Optics
- Composition
- 2D & 3D
This entry has not been translated yet and is shown in English.
The darkest band within a form shadow, lying just past the terminator, where the surface has turned fully away from the key but has not yet swung around far enough to face whatever is bouncing light back. Its presence is what stops a shaded sphere reading as flat.
In practice
Painters treat it as the tell of honest observation: the darkest value on an object is the core, not the cast shadow, and beginners reliably get that backwards.
Not to be confused with
- TerminatorThe locus on a surface where the light direction is tangent — where the normal is perpendicular to the incoming ray and direct illumination reaches exactly zero. It is a line of zero width; everything soft about it comes from the source's angular size, not from the boundary itself.
- Cast shadowThe shape an occluder subtracts from another surface's illumination. Unlike a form shadow it has a projected outline governed by the geometry between blocker and receiver: it sharpens as the two approach contact and softens as they separate, regardless of the object's own shading.
- Form shadowThe region of an object turned away from the light — unlit because of its own orientation, not because anything blocks the source. Its boundary is the terminator, its edge softens in proportion to the source's angular size, and almost everything in it arrives as indirect light.