7.4.2 Orthographic Projection Of A Line
Lines are classified according to their orientation to the three
principal planes of projection or how they appear in a
projection plane. They can also be described by their
relationship to other lines in the same view. All lines are
located from the fold lines/ reference lines, which represent
the intersection of two perpendicular planes of projection. In
fig. above, line 1-2 is pictorially represented. Line 1-2
(dashed) is projected on to each principal projection plane and
located by dimensions taken from fold lines.
Figure 7.4 Orthographic projection of a line