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Projection methods are developed along two lines perspective and parallel. Projection theory comprises the principles used to represent graphically 3D objects and structures on 2D media Drawing more than one face of an object by moving your line of sight relative to the object helps in understanding the 3D form. A line of sight is an imaginary ray of light between an observers 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 O n e - p o in t T w o - p o in t T h r e e - p o in t P a r a lle l P r o je c t io n O b liq u e C a v a lie r 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. .. 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.. .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