Technique of depicting in two dimensions objects and figures so that they appear to be placed realistically in 3 dimensions are called the theory o perspective.
The invention of perspective consisted preliminary in the realization that the diminished size of objects viewed from a distance may be governed by mathematical laws. Filippo Brunelleschi (1337-1446) was the first to discover this principle which is one the most important achievements of Renaissance art.
The law of perspective is primarily base on two factors
1. Vanishing point.
2. Eye level.
An artist must have to always remember that two things of the same volume look different from different distance. The one which is existing at far distance looks smaller and other one which is existing at nearly distance looks bigger. In a good art this method is always applied.
The theory of perspective is a mathematical law. There are two parts of perspective.
Liner perspective: the illusion of depth in a painting employed an artificial composition where all the lives lead towards the back of the picture and meet theoretically at a single point which is known as the vanishing point in the distance of view. This is the liner perspective which was the first to discover this principle by Filippo Brunelleschi.
Aerial perspective: This perspective usually depended on atmosphere. The objects of far distance look obscure because of the existence of atmosphere. So depth of color should be light to draw the objects of far distance. The nearly objects look clear and prominent. The objects of far distance sometimes look graceful and obscure. Grey color is applied to draw cloudy sky and ocean. Thus an artist applies an aerial perspective.