Light and Shadow in Art: Understanding Form Shadow and Cast Shadow
Shadows are not just dark areas. Form shadows and cast shadows serve different purposes, and confusing them flattens your drawings. Light and shadow are what give a flat drawing the illusion of three dimensions, but for years I treated all shadows as the same thing: dark areas where the light did not reach. This misunderstanding flattened my drawings, because I was using shadow to indicate that an area was dark rather than to describe the form of the object. The breakthrough came when I learned to distinguish form shadow from cast shadow, and to draw each one with its specific characteristics. Here is about each type of shadow and how to use them. Form Shadow Describes the Shape of the Object A form shadow is the shadow on the object itself, the side that faces away from the light. The form shadow is what reveals the three-dimensional shape of the object, because the gradient from light to dark across the surface describes the curvature. A sphere lit from one side has a form shadow that transitions smoothly from the lit side to the dark side, and the smoothness of that transition tells the eye that the surface is curved. More guides are on the Draw Perfect Blog.