MEANS:Light: Projection: On Plane

Perspective projection,
(http://mathworld.wolfram.com/Perspective.html)
erspective
Perspective is the art and mathematics of realistically depicting three-dimensional objects in a two-dimensional plane, sometimes called centric or natural perspective to distinguish it from bicentric perspective. The study of the projection of objects in a plane is called projective geometry. The principles of perspective drawing were elucidated by the Florentine architect F. Brunelleschi (1377-1446). These rules are summarized by Dixon (1991):
1. The horizon appears as a line.
2. Straight lines in space appear as straight lines in the image.
3. Sets of parallel lines meet at a vanishing point.
4. Lines parallel to the picture plane appear parallel and therefore have no vanishing point.
There is a graphical method for selecting vanishing points so that a cube or box appears to have the correct dimensions (Dixon 1991).