Measuring the magnitude of a issue while blocking in the drawing is an vital step in producing a reasonable rendition of the actual matter.

These angle can be reproduce on the drawing exterior and then rechecked to make sure they are accurate. Another form of quantity is to compare the relative sizes of different parts of the subject with each other. A stroke placed at a point along the drawing implement can be used to compare that length with other parts of the illustration.

A network can be used to produce a more exact portrayal of a photograph. The image is subdivided into equally spaced straight and vertical lines. A scaled version of these lines is drawn lightly on the paper, and the outlines of the significant features are copied onto the drawing. A similar draw near when using an easel is to mount a small, heavy paper frame during which the artist can view the scene. The image on the paper is then scaled in reference to this frame.

When attempting to describe a complicated shape such as a human figure, it is helpful at first to represent the form with a set of primitive shapes. Almost any form can be represented by some arrangement of the cube, sphere, cylinder, and cone. Once these basic shapes have been assembled into a likeness, then the drawing can be refined into a more accurate and polished form. The position of the primitive shapes are impassive and replaced by the final likeness.