Projection methods are developed along two lines: perspective and parallel. Projection theory comprises the principles used to represent graphically 3-D objects and structures on 2-D media Drawing more than one face of an object by moving your line of sight relative to the object helps in understanding the 3-D form. A line of sight is an imaginary ray of light between an observer''s eye and the object.
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Projection Theory
Perspective and Parallel Projections
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Projection Theory
A projection is a mapping of a 3D space onto a 2D subspace
2D space is called the projection plane
Projection also refers to image resulting from such a
mapping
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Classification of Projections
O n e - p o i n t
T w o - p o i n t
T h r e e - p o i n t
P e r s p e c t i v e
P r o j e c t i o n
C a v a l i e r
C a b i n e t
G e n e r a l
O b l i q u e
I s o m e t r i c
D i m e t r i c
T r i m e t r i c
A x o n o m e t r i c M u l t i v i e w
O r t h o g r a p h i c
P a r a l l e l
P r o j e c t i o n
P r o j e c t i o n T h e o r y
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Common Elements of a Projection System
Center of Projection
(Perspective)/Direction
of Projection (Parallel)
Projection Plane
Object(s) to be
projected
Projectors
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Some Terminology
Bounding Box = Principal Enclosing Box (PEB)
Center of Projection = Station Point =
Viewpoint of observer
Projection Plane = Viewplane = Picture Plane
Projectors = Sightlines = Line of Sight
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Projection Theory
Perspective and Parallel Projections