This makes a box the ideal shape for demonstrating it. Its form consists of the three basic directions corresponding to height, width and depth. (left pic)

Direction points are only used for illustrating forms foreshortening away from us. And so only those parts of a form that are angled away will get a direction point. Ordinarily, such a form allows for up to three, according its three overall directions.

This is the basis of using one-point perspective, two-point perspective and three-point perspective techniques, which are the backbone of linear perspective.

The number of direction points used, then, has nothing to do with where an object is located within our picture but how it is angled to us.

Generally, the more direction points used, the more three-dimensional an object will look since this will give us more viewing angles of it. So to see something as close to one angle as possible, use one-point perspective. To see it mostly from two angles, use two-point perspective. These, however, are very general rules being that even a form in one-point perspective can clearly display three different angles of it. (left pic)

Commonly, we will have a combination of one, two and three-point perspectives among the differently positioned forms present. These methods, then, should not be confused to mean that all forms in the scene should go to just one, two or three direction points. We may not want all forms pointing the same way since mixing them up can make for a more interesting picture.

Linear perspective has limited application since it deals mainly with drawing with lines on flat surfaces, excluding it from any art form like stage, window display or designing amusement park attractions. Although we can still see converging lines in reality, there is no means of looking at a box in a way that would only require one direction point. It will have direction points for every direction pointing away from us. (left pic) A large form could even extend to direction points behind us.

Also, even with a majority of man-made forms being based on right angles and straight, parallel lines, we will find almost nothing of these in nature nor in any life form whether animal or vegetation. We could paint many hundreds of landscapes and seascapes without using one single direction point and set of parallel lines. Really, there is only so much you can express through converging lines.

Yet, I have read that "You cannot understand perspective unless you understand the cube." The basis of this limited thinking is merely that one, two and three-point perspective methods are based on forms made of right angles, as cubes are.

And since everything in the world isn't made of right angles nor can be drawn with converging lines, linear perspective will call for the outlining of all objects, even curved or irregular forms, with rectangles or boxes so its techniques will more-or-less function (which can be workable).

Beyond Linear Perspective

As workable as linear perspective is, it does not realize the full extent of what perspective is. Learn more, read:

A New Perspective - Universal Edition

A New Understanding of Perspective
for All Visual Art Forms Including:
Drawing, Painting, Photography, Motion Picture,
3D Graphics and Video Game Design

Visit www.perspective-book.com.

With it, for the first time ever, realize fully how flawed so many of our techniques have been and how very limited our understanding of perspective actually was.