Microsoft Word - lecnote_fm_engineering drawing

Figure 7.14 Orthographic projection of oblique lines

So, the true length of an oblique line can be measured in a
view where the line is parallel to the projection plane of that
view. And if the line of sight for a view is not perpendicular to
the line, the line will be foreshortened.

Since oblique lines are not true length in a principal plane, it is
necessary to project an auxiliary view in which the given line
appears true length. An oblique line appears foreshortened in
all three principal views: frontal, horizontal, and profile. In
order to have a true length of a line, the line must be parallel
to the projection plane in the adjacent view.

A true length view of an oblique line can be projected from
any existing view by establishing a line of sight perpendicular
to a view of the line and drawing a fold line parallel to the line
(perpendicular to the line of sight). The following steps