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The six principal views of an object or the glass box have
previously been presented in the type of orthographic
projection known as Third Angle Orthographic Projection. This
form of projection is used throughout this lecture note and is
primary form of projection found in all American Industry with
the exception of some special cases in the architectural and
structural fields.

Figure 5.10 Third angle projections

The type of projection used in most foreign countries and on
many American Structural and architectural drawings is called
First Angle Orthographic Projections.

In this form of projection, the object is assumed to be in front
of the image plane. Each view is formed by projecting through
the object and on to the image plane.