Perspective involves four main elements; the observers eye, the object being
viewed, the plane of projection, and the projectors from the observers eye to
all points on the object. Other terms you should become familiar with are
plan and elevation, picture plane, vanishing point, horizon line, ground line,
and visual rays.
THE OBSERVERS EYE: The observers eye, also known as the station
point (SP), represents the location of the eyes of the observer. You should
direct the centerline (CL) of the cone of visual rays toward the center of
interest. For small or medium-sized objects, place the station point slightly
above the object. For large objects, place the station point at eye level or
approximately 5 feet 6 inches above ground. The station point is the most
influential element of perspective drawing because it affects location,
viewpoint, and perspective.
Figure 5-2 shows the centerline of a cone of visual rays.
Figure 5-2.The cone of visual rays.
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