What Is an Isometric Drawing?
Have you ever tried to draw a 3-dimensional shape, such as a cube? It can be a bit of a challenge. Every artist faces the challenge of creating 3-dimensional images on 2-dimensional paper. A painter or sketch artist may use techniques such as shadowing to make the image appear as lifelike as possible. For a technical or engineering drawing, however, different strategies have to be used. This is where an isometric drawing becomes useful.
Isometric drawing, also called isometric projection, method of graphic representation of three-dimensional objects, used by engineers, technical illustrators, and, occasionally, architects. The technique is intended to combine the illusion of depth, as in a perspective rendering, with the undistorted presentation of the object’s principal dimensions—that is, those parallel to a chosen set of three mutually perpendicular coordinate axes.
The isometric is one class of orthographic projections. (In making an orthographic projection, any point in the object is mapped onto the drawing by dropping a perpendicular from that point to the plane of the drawing.) An isometric projection results if the plane is oriented so that it makes equal angles (hence “isometric,” or “equal measure”) with the three principal planes of the object. Thus, in an isometric drawing of a cube, the three visible faces appear as equilateral parallelograms; that is, while all of the parallel edges of the cube are projected as parallel lines, the horizontal edges are drawn at an angle (usually 30°) from the normal horizontal axes, and the vertical edges, which are parallel to the principal axes, appear in their true proportions.
A Third Dimension
It is simple to draw a 2-dimensional object on paper because paper has two dimensions, height and width. But objects in real life have a third dimension, depth, which needs to be represented in the drawing. In isometric drawings, all three dimensions are represented on paper.
The three dimensions are represented as three axes: one vertical axis and two horizontal axes.
It’s All About the Angles
So what makes an isometric drawing different from other 3-dimensional drawings? The axes are drawn so that the two horizontal axes are drawn at 30 degree angles. It’s as if the vertical axis is in its true position, but the horizontal axes are bent 30 degrees from their true position.