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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.
Projection Theory Perspective and Parallel Projections 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 Classification of Projections P r o je c t io n T h e o r y P e r s p e c t iv e P r o je c t io n P a r a lle l P r o je c t io n O n e - p o in t O b liq u e T w o - p o in t C a v a lie r T h r e e - p o in t C a b in e t G e n e l O r t h o g r a p h ic A x o n o m e t r ic I s o m e t r ic D im e t r ic T r im e t r ic M u lt iv ie w Common Elements of a Projection System Center of Projection (Perspective)/Direction of Projection (Parallel) Projection Plane Object(s) to be projected Projectors 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 Projection Theory Perspective and Parallel Projections ... Center of Projection = Station Point = Viewpoint of observer Projection Plane = Viewplane = Picture Plane Projectors = Sightlines = Line of Sight Projection Theory Perspective and Parallel Projections. .. r im e t r ic M u lt iv ie w Common Elements of a Projection System Center of Projection (Perspective) /Direction of Projection (Parallel) Projection Plane Object(s) to be projected Projectors.. .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