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Presentation topic. PARALLEL PROJECTION. PARALLEL PROJECTION. PROJECTION MAPPING METHODS OF PROJECTION PARALLEL PROJECTION. PROJECTION.

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### Presentation topic

PARALLEL PROJECTION

PARALLEL PROJECTION
• PROJECTION
• MAPPING
• METHODS OF PROJECTION
• PARALLEL PROJECTION
PROJECTION
• For centuries, artists, engineers, designers, drafters, and architects have been facing difficulties and constraints imposed by the problem of representing a three-dimensional object or scene in a two-dimensional medium.
• The implementers of a computer graphics system face the same challenge.
PROJECTION
• The subject of projection will help you to display three dimensional model on two dimensional medium (screen)…
MAPPING
• Projection can be defined as a mapping of point P(x,y,z) onto its image P`(x`,y`,z`) in the projection plane or view plane, which constitutes the display surface.
• The mapping is determined by a projection line called the projector that passes through P and intersects the view plane.
MAPPING
• We can mapping a point in three dimensional on a view plane Where viewer can view from their point of view..
METHODS OF PROJECTION
• PARALLEL PROJECTION
• PERSPECTIVE PROJECTION
TAXANOMY OF PROJECTION
• We can construct different projections according to the view that is desired.
• These methods are used to solve the basic problem of pictorial re presentation.
• (how to display 3D model in 2D screen)
PARALLEL PROJECTION
• In parallel projection, image points are found as the intersection of the view plane with a projector drawn from the object point and having a fixed direction.
• The direction of projection is the prescribed direction for all projections.
USE OF PARALEL PROJECTION
• Parallel projection methods are used by drafters and engineers to create working drawings of an object which preserves its scale and shape.
• The complete representation of these details often requires two or more views (projections) of the object onto different view plan.
Mathematical Description of a Parallel Projection
• Projection rays (projectors) emanate from a Center of Projection (COP) and intersect Projection Plane (PP).
• The COP for parallel projectors is at infinity.
• The length of a line on the projection plane is the same as the "true Length".
figure

Center of projection at infinity

Direction of projection(DOP)

Same for all points.

PURPOSE OF PARALLEL PROJECTION
• To design model of exact measure of original model
• So scale and shape will not change by changing of point of views.