PERSPECTIVE PROJECTION
Perspective projection represents a three-dimensional
object by projecting all its points to a picture plane by
straight lines converging at a fixed point in space
representing a single eye of the observer. This
convergence of sightlines differentiates perspective
projection from the other two major projection systems,
orthographic projection and oblique projection, in which
the projectors remain parallel to each other.
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The picture plane (PP) is an imaginary
transparent plane on which the image of a
three-dimensional object is projected. The
picture plane is always perpendicular to the
central axis of vision (CAV).
Sightlines are any of the projectors extending
from the station point (Sf) to various points on
what is viewed.
----~ The perspective projection of any point on an
object is where the sightline to that point
intersects the picture plane.
11 ILJ.A---''
The central axis of vision (CAV) is the sightline
determining the direction in which the observer
is assumed to be looking.
- The station point (Sf) is a fixed point in space
representing a single eye of the observer.
PERSPECTIVE DRAWINGS I 89