First of all,,, what is 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|
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 the same 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. However, as you can see from the above table, it is not the only thing needed to do this.
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.
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 (belo right).
Whats the use of perspective?
Perspective has two main uses: to show position