Perspective drawing is the method by which a three dimensional scene can be rendered on a two dimensional sheet of paper. This exercise served as an introduction to perspective technique. Perspective art can be categorized by its number of vanishing points. The following three pictures are examples of that.
One Point Perspective
Two Point Perspective
Three Point Perspective
Perspective technique is not limited to straight lines. Circles viewed at an angle are rendered below to explore the technique. On the paper, they are drawn as ellipses.
The trick is to mark the diagonals of a square 2/3 of the way towards the edges, then draw the ellipse through those points.