In working toward establishing this sense of depth and three-dimensionality, there are a number of ways to create the illusion—Figure 2.5 is a deep focus shot from Citizen Kane, photographed by Gregg Toland; it shows a great sense of depth in a visual field. In terms of the editing, it is useful to view a scene from more than one angle—shooting a scene entirely from a single angle creates what we call flat space. Elements that create a sense of visual depth include:

Overlap
Size change
Linear perspective
Foreshortening
Chiaroscuro
(there are more!)

Overlap
Overlap clearly establishes front/back relationships; something “in front of” another thing is clearly closer to the observer…

Relative Size
Although the eye can be fooled, the relative size of an object is an important visual clue to depth… Relative size is a component of many optical illusions and a key compositional element in manipulating the viewer’s perception of the subject; it can be used to focus the viewer’s attention on important elements. There are many ways to manipulate relative size in the frame, using position or different lenses.

Linear Perspective
Linear perspective was an invention of the Renaissance artist audience, such as this frame from Brunelleschi. In film and video photography, it is not necessary to know the rules of perspective, but it is important to recognize its importance in visual organization. Director Stanley Kubrick uses it to reinforce the rigid nature of French society in Figure 2.10, a frame from Paths of Glory; he uses strong geometry in Dr. Strangelove (Figure 2.23) for similar storytelling purposes.

Foreshortening
Foreshortening is a phenomenon of the optics of the eye. Since things that are closer to the eye appear larger than those farther away, when part of an object is much closer than the rest of it, the visual distortion gives us clues as to depth and size.