Summary of Orthographic Projection
Orthographic projection is a means of representing three-dimensional objects in three (3) two-dimensional views. That is, it depicts a 3-D object in three 2-D views.
For orthographic projection, there are three principal (basic) planes, which are vertical, horizontal and profile planes.
Also, there are six principal views which are top and bottom, front and back; and left and right side.
A first angle projection places the object in the first quadrant of the three intersecting planes.
A third angle projection places the object in the third quadrant of the three intersecting planes.
In the first angle projection, the top/plan view is at the bottom of the drawing.
In the third angle projection, the top/plan view is at the top of the drawing.
For orthographic projections, all dimensions are drawn to scale.
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