There are three types of perspective in sociology. A perspective is simply a way of looking at the world. They are Functionalist perspective, conflict perspective and symbolic Interactionist perspective.

No observe is simply to watch, perspective describes viewpoint of the watcher.

geometry ~Apex

c. Renaissance

Perspective is science of describing visual form and volume on a flat space. Although almost exclusively taught as linear, the most correct representation is curvalinear, due to the fact that the eye, including the retina is curved, as it the earth, not flat. Perspective offers "realism" for the viewer's mind to register. It is a clear break from symbolism.

Perspective is aided by color temperature, a variation in color relationships designed around increasing orange or blue for warm or cool respectively. The portrait is considered "most difficult" due to not only the first obstacle, spacial relationships, but more mystically, color temperature. "Skin color" has warm reds, Oranges, yellows and cool purples, greens and grays. Where you place these variations affects the perspective of form.

The short answer is Perspective helps create believable form with distance. Variations in color can create depth perception over very large atmosphere or very small areas such as the distance from cheek to lower eye lid.