Perspective (graphical)
Graphical perspective attempts to approximate on a planar surface an image as it is perceived by the eye. An exact replication is impossible. (See Perspective projection distortion.
This approximation is either executed intuitively by freehand sketching or else by employing certain geometric protocols with drawing instruments. In the former case it is generally referred to as artistic, spatial foreshortening; in the latter case it is referred to as Perspective projection.
History of perspective
The physiological basis of foreshortening went undefined until the year 1000 when the Arabian mathematician and philosopher, Alhazen, in his Perspectiva, first explained that light projects conically into the eye. A method for presenting foreshortened geometry systematically on a plane surface was unknown for another 300 years. The artist Giotto may have been the first to recognize that the image beheld by the eye is distorted---that to the eye, parallel lines appear to intersect (in the manner of receding railroad tracks) whereas in "undistorted" nature, they do not. One of the first uses of perspective was in Giotto’s ‘Jesus Before the Caïf’, more that 100 years before Brunelleschi’s perspectival demonstrations galvanized the widespread use of convergent perspective of the Renaissance proper.
Artificial perspective projection is the name given by Leonardo da Vinci to what today is called classical perspective projection. Natural perspective projection is the name given by Leonardo to the projection that produces the image beheld by the human eye. Both types of projection involve a distortion; parallel lines never intersect in nature, but they always intersect in perspective projections, with the rare exception wherein both the surface of projection is planar and an object plane is spatially parallel to the plane of projection.
The difference between the images of the same object produced by artificial perspective projection and by natural perspective projection is called perspective distortion.
Related articles
Perspective projection distortion, Perspective transform, Desargues' theorem, Perspective (visual)