Shadow perspective

Accurate application of shadow, especially cast shadow, defines three-dimensional space. This is one of the most powerful uses of chiaroscuro.

In the top example, even with foreshortening and overlap visual cues, the space is fairly flat. In the lower example, the addition of form shadow on the frontmost object, and cast shadow from it, space is much more clearly defined and the illusion of dimensionality is greatly strengthened. This is just a beginning—adding form shadow to the rearmost object, and a cast shadow from it, would enhance the effect.