This document discusses visual elements and techniques for creating a sense of space and volume in two-dimensional artwork. It explains that physical objects have three dimensions of length, width, and height which define their volume. The document then presents three techniques for indicating depth on a flat surface: using relative size with smaller objects appearing farther away; superimposing one shape over another; and employing contrasts in color, light, and detail level with colder/lighter/less detailed areas seeming more distant. Examples are provided to illustrate each spatial perception method.