Item 
Environment installation / Drawing / conception

Course 
Perspective 
Chapter 
Introduction & definition 
Period of training required

24h 
Publication Date

31/03/2015 
End of training period (suggested) 
02/04/2015 
Offline

14/04/2015 
INTRODUCTION
Perspective allows an artist to control the illusion of depth in an image with space ranging from a few inches to many miles. Linear and atmospheric perspective must be used together to make the illusion effectively. You will study each in turn then construct a photomontage that exhibits your understanding of both. Both systems of perspective describe how objects appear in relation to their distance from the observer. This is not so much science as a means of describing, and by interpretation of illustrating, objects in space.
DEFINITION
Perspective, in the context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects. There are two main meanings of the term: linear perspective and aerial perspective.
LINEAR PERSPECTIVE
It seems obvious that the apparent size of an object decreases the farther you get away from it. It is a surprise that this has not always been understood to be so. There is some indication from looking at mosaics that the ancient Greeks knew how to use perspective but no documents from that time have survived. The first written information about linear perspective appeared about 400 years ago. It was in Europe during the Renaissance that the concept of linear perspective was finally formalized.
Linear perspective is a system for drawing objects that use lines and vanishing points to determine how much an object's apparent size changes with space.
BASIC CONCEPTS
The horizon line is a theoretical line that represents the eye level of the observer. The horizon line is the same as the horizon (the edge of the land against the sky) only on a large flat plane like the ocean. Most of the time geographic features (hills) and other objects (trees and buildings) make the horizon above the horizon line.
Indoors the horizon is often not visible but there is still a theoretical horizon line representing the point of view of the observer.
Look at the three sketches below. The same telephone pole is in the same position in all of the formats. The horizon (line) is different. Can you tell where you are in relationship to the poles?
The first pole is seen from above, the second from normal eye level and the third appears to be floating over your head. An object's relationship with the horizon line shows whether you are looking up, down or straight at the object.
Vanishing points are points (usually) on the horizon line where receding lines (planes) converge. The vanishing point (v.p.) is on the horizon line when an objects has horizontal planes that are parallel to the ground. When the object's planes are inclined the vanishing points can be above or below the horizon line.
Objects that are placed parallel to one another use the same vanishing points. Objects set at different angles each have their own vanishing points.
There are two basic systems of linear perspective: onepoint and twopoint named after the number of vanishing points used in each.





 All parallel lines follow the same rules. If one goes to a vanishing point then all like lines go to the same vanishing point. In most systems vertical lines are drawn vertical (not in threepoint perspective).
 The station point represents the eye of the observer. It is the camera in a photograph.
 The picture plane is the "window" that is represented by the picture.
 The ground line is a line that is parallel to the picture plane at the base of the object being depicted.
ONEPOINT PERSPECTIVE
Onepoint perspective is what you see when you look straight at the side of an object. It uses only one vanishing point, hence its name.
The line of sight in onepoint perspective is perpendicular (at a right angle to) the side of the cube in these examples. That means you see the near side in plane view (actual shape undistorted by perspective)
There are only three kinds of lines used in onepoint perspective:
Vertical edges are shown as vertical lines.
Horizontal edges (perpendicular to the line of sight and parallel to the ground) are shown as horizontal lines.
Edges that recede (are parallel to the line of sight) are on lines that converge at the vanishing point on the horizon line.
Note that these same three (and only these three) kinds of lines are used to draw the cubes regardless to where they are in the picture.
Also note that the cube to the left, while technically correct, appears distorted. Onepoint perspective only depicts objects near the vanishing point with accuracy.
TWOPOINT PERSPECTIVE
Twopoint perspective is used when you look at or into the corner of an object. There are two vanishing points since the two sets of sides are receding in two different directions.
In the real world vanishing points are very far apart. Imagine strings streaming out parallel to the edges of a cube going to the horizon. The horizon is miles away so the vanishing points are many miles apart. When you draw them only a few inches apart on a piece of paper there is going to be some distortion in the image produced.
Again there are only three different kinds of lines needed to draw in twopoint perspective:
Verticaledges are drawn as vertical lines.
Edges of sides that recede toward the right are on lines converging at the right vanishing point.
Edges of sides that recede toward the left are on lines converging at the left vanishing point.
Both of the cubes in the example use only the same three kinds of lines. You see the top of the cube below the horizon line (your eye level). You see the bottom of the cube above the horizon line and more of its left side because it is to the right of your position in the center of the vanishing points.
cf.
http://en.wikipedia.org/wiki/Perspective_%28visual%29
http://daphne.palomar.edu/design/space2.html
To deepen :
http://www.bbc.co.uk/schools/gcsebitesize/design/graphics/drawingformalrev1.shtml
http://www.artyfactory.com/perspective_drawing/perspective_index.html
http://en.softonic.com/s/freeperspectivedrawing
cf.