Perspective drawing is a system for creating a two-dimensional illusion of a three-dimensional subject or space. Information, whether it's observed or imagined, is translated into a system that allows three-dimensional forms and space to be represented on a two-dimensional surface; creating the appearance of viewing real space on a page.
Perspective theory is often separated into two parts, linear perspective, and atmospheric perspective.
Linear perspective addresses how the shapes, edges and sizes of objects change in appearance when seen at different positions relative to the observer. The distance between the object and the observer, the rotation and elevation of the object, and the viewing angle of the observer are all important in linear perspective. The location of the horizon line, the eye level of the observer, the line of sight of the observer, the location of vanishing points, and the use of trace points and receding lines are key to this practice as well.
Atmospheric perspective is used to identify other characteristics that convey how near of far an object is from the observer. A veil of atmospheric haze usually reduces the visibility of far away objects. With distance, detail is obscured, contrast is reduced and color is less intense.
The basics of perspective have been known since ancient times; overlapping, diminishing size, and atmospheric perspective can be found in art well over 1,000 years old. It wasn't until the 14th century that perspective theory was analyzed in depth and its principles were developed to a high degree of sophistication. Filippo Brunelleschi, the Italian Renaissance architect, is credited with the invention of linear perspective, the system of translating three dimensions into two. Some say it was really an invention from the Dutch artists of the time and Dutch painters of the 15th and 16th centuries really brought the illusion to its peak.
All perspective drawings have two major characteristics that create a sense of space, depth, and volume. One is convergence; the apparent diminishing distance between parallel edges of an object as they move farther away from the observer. Parallel lines seem to come together in the distance, eventually meeting at the horizon. The other is foreshortening; the apparent diminishing size of the width or height of an object as it angles away from the observer. Sides and tops of objects seem to get shorter and flatter as they move away.