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principal advantage of axonometric drawing is that one can use an existing orthographic plan without
any redrawing. The plan is simply tilted to the desired angle. It should be noted that in much of Europe,
an axonometric drawing always has its axis at a 45-degree angle; an isometric axis is either 30/30 de-
grees or 30/60 degrees. The most common axonometric drawings are isometric, dimetric, and trimetric
(Figure 5.16). Typically in axonometric drawing, one axis of space is shown as the vertical.
Axonometric, or planometric, drawing, as it is sometimes called, is a method of drawing a plan view
with a third dimension. It is used by interior designers, architects, and landscape gardeners. A plan view
is drawn at a 45-degree angle, with the depth added vertically. All lengths are drawn at their true lengths,
unlike oblique drawing. This gives the impression that you are viewing the objects from above. One ad-
vantage of axonometric drawing is that circles drawn on the top faces of objects can be drawn normally.
Isometric Drawing and Isometric Projection.
The term “isometric” is derived from the Greek for “equal measure,” reflecting that the scale along each
axis of the projection is the same, which is not true of some other forms of graphical projection. One of
the advantages of isometric perspective in engineering drawings is that 60-degree angles are easy to
construct using only a compass and straightedge.
The isometric drawing is most commonly used in its true form giving “equal measure” and foreshort-
ened views of three sides of the object. An isometric drawing is one form of pictorial drawing. Hidden
lines are not normally inserted. Isometric drawing is a method of visually representing three-dimensional
objects in two dimensions, in which the three coordinate axes appear equally foreshortened and the an-
gles between any two of them are 120 degrees. Isometric projection, like orthographic projection. is used
in engineering drawings. An isometric drawing can be easily constructed by using a 30-60-90-degree tri-
angle and T-square or with CAD programming. Figure 5.17A and B shows two examples of isometric
drawings in an architectural context. Figure 5.17C gives an example of an architectural drawing using
both orthographic projection (elevation) and isometric projection (details).
Figure 5.16 Different types of axonometric projections (isometric, dimetric, and trimetric) and perspective. In
much of Europe, an axonometric uses a 45-degree angle as opposed to the 30/60-degree angles used in
isometric drawing.