Figure 3-4.

Vertical division

4. The cube is in many ways the most important single shape you will study

in your art career. Both simple and complex structural development can be

illustrated by this one geometric form.

Its importance will become

increasingly evident as you work with three-dimensional forms and

measurement, especially when you draw objects in perspective.

As the

preceding text segment pointed out, in order to solve many practical

problems in perspective, you will use the cube or some portion of it as a

medium of measurement. This may be a tedious business because you may make

several sketches before you get an acceptable drawing. But it is time and

effort well spent. Some artists who make cubes too wide or too narrow have

never really learned what a square, hence a cube, looks like in perspective.

a. Although the cube is perhaps the most important shape, the circle is

the guide for drawing all two-dimensional curves, ellipses and ovals in

perspective. Even so, its basis is the square, or one surface of the cube.

The square is used because there are no direct measurements on a curve in

perspective.

Vanishing points are determined from the square, and

proportions of the curve can easily be seen within the square. Figure 3-5

shows the proper layout of a circle in perspective. The first step in the

instrument layout is to draw a circle with the desired dimensions. Second,

draw the square around the circle and add the diagonal and centerlines as

shown in step 2.

This will give you eight checkpoints for drawing the

circle in perspective. Next, draw the perspective lines back to the desired

vanishing point to establish the square in perspective.