ISOMETRIC DRAWINGS
Isometric drawings establish a lower angle of view
than plan obliques and give equal emphasis to the
three principal sets of planes. They preserve the
relative proportionsof asubject or scene and are not
subject to the distortion inherent in obliqueviews.
• To construct an isometric drawing, first establ ish
the direction of thethree principal axes. Because
they are 120° apart on the picture plane, if we draw
one axis vertically, the ather two axes make a30°
angle with a horizontal on the drawing surface.
• Then lay out the true lengths of all lines parallel to
the three principal axes and draw t hemto the same
scale.
• Isometric drawings offorms based an the square
can create an optical illusion and be subject to
multiple interpretations. Thisambiguity results
from the alignment of lines in the foreground with
those inthe background. insuch cases, aplan
oblique might be abetter choice.
76 I ARCHITECTURAL GRAPHICS