PRIN. OF DRAFTING AND SHOP DRAWINGS - OD1641 - LESSON 1/TASK 1
e. Points. Projection theory is the study of how to transfer information from one
orthographic view to another. Often, two views of an object may be visualized, or
parts of each view may be drawn, but the completed drawing remains unclear.
Projection theory enables the bits and pieces to be used together to arrive at a
finished drawing.
Reduced to its simplest form, projection theory may be used to transfer a single
point from one view to another. Figure 6 presents the problem of finding the right
side view of a point where the front and top views are given.
FIGURE 6.
TOP AND FRONT VIEWS
OF POINT 1.
Figure 7 (on the following page) shows the solution.
Project the front view of
point 1 into the right side view zone.
This is done by drawing a horizontal
construction line parallel to the horizontal principal plane line.
The tendency
here is to draw the projection line too short, meaning extension may be required
later on. All we know at this time is that the right side view is somewhere along
the projection line.
6
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