Depth - Illusion of Space

SIZE OF OBJECTS-smaller objects seem farther away (distortions can occur if objects are the same size or too close to the viewer).
OVERLAPPING OR SUPERIMPOSING-by partially covering one object with another it gives an appearance of depth (distortions also occur if viewer is too close).
TEXTURE-density increases as an object gets further away.
SPACING-objects clustered closer together seem farther away. Horizontal lines which get closer as they near the horizon line appear to be defining a recession in space.
FOCUS-objects lose detail as they recede into space.
BRIGHTNESS-objects are brighter when closer to the viewer, except for reflective surfaces.
SHADE AND SHADOW-darker shadows seem closer especially if overlapping other shadows.
UPWARD ANGULAR LOCATION-creates depth if juxtaposed to ground and sky lines, e.g. tall buildings.
COLOR-color intensity is much greater closer to the viewer and tends toward medium gray as it recedes.
Hint: As objects recede away from the viewer in atmospheric perspective, bright whites and rich blacks tend toward medium gray and eventually disappear into a blue/gray background. Even colors have greater intensity closer to a viewer than they do further away.