They run from top to bottom and from side to side at right angles to each other, and from corner to corner diagonally through the center of the format where all tensions cross unless modified by a tendency of the eye to seek an area just above the middle as the psychological center, the visual center, as it is sometimes called. The psychological and physical peculiarities of the flat surface do not end there.
Pictorial depth enhances the quantity and, in many works, the quality of the space.
Our aim, therefore is to become extraordinarily aware of this phenomenon in order that it may be used to structural and expressive advantage. When combined, they can create a powerful illusion of depth. Linear perspective . This cue is based on the apparent convergence of parallel lines in the environment. If you stand between two railroad tracks, they appear to meet near the horizon.