Perspective is a system of drawing. It is the only complete system that art has: good perspective now is the same as good perspective one hundred years ago and will be equally good in one hundred years. This system was first formulated by 1021 Alhazen (Abū ʿAlī al-Ḥasan ibn al-Ḥasan ibn al-Haytham) and has ever since been vital to the realistic depiction of depth space within a picture plane.
What isn't perspective?
First of all... what isn't perspective? I ask the question because it is a term that is often used poorly or inaccurately. Take the image below: the trees in the distance look like they are in the distance because:
|Atmospheric distortion||No atmospheric distortion||No|
|Is of low lightness contrast||Is of high lightness contrast||No|
|Has fuzzy edges||Has sharp edges||No|
|Is small||Is large||Yes|
You will notice that perspective plays a relitivly small part in the space construction of the image.
What goes wrong?
I shall detail below some facts about perspective through an attention to the common mistakes that students make. As perspective is an entirely taught thing, these mistakes are rooted in the way that we draw as children (a.k.a.: a 'pre-taught' state). In the first of the drawings below, the front edge of the table is parallel with the edge of the paper (i.e. the horizontal) and the two sides are also paralel with each other (centre image). In the right-hand image the table has been re-drawn 'correctly'.
The reasons for this 'wrongness' are outlined in the following images. A common mistake is to 'lift' the surface plane up so that it presents in map view (below).
Map view is inherent to the 'pre-trained' childhood drawing condition. It presents the world in the same way that we experiance it.
A side view shows that all the edges of the table (below left, in green) are not parallel with each other. Yet we are inclined to draw them as such (below right).
Whats the use of perspective?
Perspective can be used to 'force' a point of view (and thereby an emotional context) upon the viewer. The image below on the left is a perspective schematic of an adult walking into a room full of adults. On the right is the same room full of adults from the point of view of a child.
Feeling dizzy? A drawing by the great drawing systems artist: M. C. Echer.
Perspective can also be used to indicate scale. In advertising, anything 'box like' tends to have a somewhat extreme three point perspective forced upon it. This makes us feel that the object is far bigger than it is. In the image on the right I have removed this perspective.
My slide talk on perspective (from which some of this material is taken): Perspective_s.pdf (right click download)