Types of Views 89
The distinguishing feature between projections and drawings is the unit of measurement employed.
In projections a scale is constructed, which is used for measurements takeoff. The units of measurement
used however are variable depending on the projection, and standard units of measurement are not
used; in drawings, however, standard units of measurement (e.g. inches, feet, centimeter, etc.) are al-
ways used. The scales constructed for isometric, dimetric, and trimetric projections are always smaller
than the standard units of measurements from which they are derived. This basically means that axono-
metric projections are always smaller than axonometric drawings. An axonometric drawing of an object,
although slightly distorted, is nevertheless visually as satisfactory as an axonometric projection of it. Ax-
onometric drawings are usually preferred to axonometric projections because no time is wasted con-
structing the scales needed to generate the axonometric drawings.
An axonometric drawing is one that is accurately scaled and depicts an object that has been rotated
on its axes and inclined from a regular parallel position to give it a three-dimensional appearance. The
Figure 5.15 Another example of an auxiliary-view projection showing how it relates to an orthographic
projection.