along all three axes. This is called an isometric

In oblique

projection (fig 1-11), and is the most common type in

drawings (fig 1-12) the front face of the object is

technical work. All lines parallel with one of the

drawn in orthographic form, full scale. One or more

three principal axes are foreshortened by the same

sides are then added at an angle to the front face,

amount (to about 81 percent of true length) on an

either full scale, or foreshortened. Any angle and

isometric projection. In isometric drawing (fig 1-11)

scale may be used.

the common practice is to enlarge the scale factor so

that lines appear in true length. Remember, however,

that this applies only to lines which are parallel to

drawing in which the receding or oblique lines are

one of the axes.

drawn full-scale at 45 degrees is called a cavalier

drawing (fig 1-12). The result does not create a

realistic appearance, but allows the use of one scale

for the entire drawing.

A cabinet

do when you look at an object. The perspective may

drawing is an oblique drawing which uses half-scale

be two-point (two vanishing points) as illustrated in

measurements on the oblique sides (fig 1-12). These

figure 1-13 or one-point (one vanishing point) as

drawings are commonly drawn with the oblique lines

illustrated in figure 1-14. In a one-point perspective,

at 30 degrees or 45 degrees to the front plane. The

the front face appears as if you were looking at it

name comes from the fact that it is often used for

head-on. The viewing angle may be changed by the

drawings of cabinet work.

selection of different positions relative to the horizon

(fig 1-14). Perspective drawings are more difficult to

The most

draw than projections or oblique drawings, because

realistic pictorial is the perspective drawing. In this

the scale changes continuously along the receding

type of drawing, the receding lines converge at a

lines; for this reason, they are not practical for

vanishing point on a horizon, just as they appear to

construction drawings.

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