G. Point View of a Line
A line will project as a point view when the line of sight is
parallel to a true length view of the line; in other words the
point view is projected on a projection plane that is
perpendicular to the true length. Finding the true length and
the point view of a line will be required for many situations
involving the application of descriptive geometry to
engineering problems. The first requirement for a point view is
that the line be projected as a true length.
The point view of a principal line is established by the use of a
primary auxiliary view as shown below. The steps are:
Step 1: Establish a line of sight parallel to the true length line
(^1) H-2H.
Step 2: Draw the fold line perpendicular to the line of sight
(H/A or H/B). Note that the fold line is also
perpendicular to the true length line.
Step 3: Draw a projection line from line 1H-2H perpendicular to
the fold line and therefore parallel to the line of sight.
Step 4: Transfer dimension D1 from the front view to locate
both points along the projection line, in either
auxiliary view A or B.