Perspective projection distortion

This page is about graphical perspective projection, specifically about distortion

Perspective projection distortion is the mechanism that permits a draftsman or artist to produce linear perspective. It is accomplished by a geometric protocol that exhibits the inevitable distortion of three-dimensional space when “projected," i.e., drawn, on a two-dimensional surface. The words projected/projection here refer to the use of graphics’ lines in the protocol to simulate light ray traces from a Station Point (a supposed observer´s location) to the edges and corners of an object in space, creating thereby or by their extension, an image at the lines’ points of intersection with a Projection Plane.

No type of projection can perfectly map the imagery of three dimensional space onto a projection plane because of the image's (mapped on the retina-sphere) undevelopability. This is a distortion of the drawing in itself called perspective projection distortion, and refers to the difference between the drawing and the way the objects depicted on it would look if it was real, but there is another distortion caused by the difference between the location of the supposed observer situated for the drawing process and the location of the real observer of the drawing. These two distortions exist simultaneously. In the special case — and the only instance — in which perspective imagery appears affected only by the perspective projection distortion, the real observer must view the perspective imagery from precisely the supposed station point of the perspective.

Real human vision and perspective projection should (unless it is otherwise desired) look the same. The difference should be imperceptible. The base to rate the quality of the perspective projection is the real vision and the difference between them is the perspective projection distortion. Normal human vision should not be considered to present any distortion unless a disturbing factor is involved. Distortion in human vision appears when there is a visual problem involved. The use of lenses can also cause, modify or avoid these distortions. In photography a lens may magnify distortion.

The physiological basis of visual foreshortening was 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 onto 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 apparently distorted (foreshortened): to the eye, parallel lines appear to intersect (like the distant edges of a path or road), whereas in "un−distorted" nature, they do not. One of the first uses of perspective was in Giotto’s Jesus Before the Caïf, more than 100 years before Filippo Brunelleschi’s perspectival demonstrations galvanized the proper widespread use of convergent perspective of the Renaissance.

...
Wikipedia