Before you begin working through this unit, there are two important concepts you should understand. Linear perspective refers to the visual methods artists use to create an illusion of three-dimensional space on a two-dimensional surface. The system is based upon an optical illusion in which parallel horizontal lines appear to converge at a common point, called the vanishing point, as they extend into the distance. This concept is shown in the photograph below.
Below there are listed certain important definitions. Your understanding of these terms is crucial to an overall understanding of linear perspective.
1-Proportion is the comparison of linear measurements of an object; it’s the relationship, or ratio, of one major dimension to another.
2- Viewpoint, or station point, refers to the location of the artist when he or she is viewing a subject.
3- The line of vision is an imaginary straight line running from the eye of the observer to the subject.
4- A right angle is a 90-degree angle between two adjacent sides, planes, or edges.
5- Horizontal describes an edge or plane that’s parallel to the ground.
6- Vertical means upright. Vertical edges or planes are at right angles to the horizontal plane.
7-Parallel describes lines, edges, and planes that are equidistant at all points and extend in the same direction, never meeting.
8-Format refers to the boundaries of the picture plane. A vertical format is longer from the top to the bottom than from side to side; a horizontal format is wider from side to side than from top to bottom. The vertical format is called a portrait orientation, while the horizontal format is called landscape orientation.
9- Eye-level is the height at which your eyes are located concerning the horizontal plane. The eye-level line extends from where a person’s eyes are at any given moment, be that person standing, sitting, crouching, lying down, or so forth.