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Unformatted text preview: CS 455 Computer Graphics Viewing Transformations I Motivation Want to see our virtual 3D world on a 2D screen Graphics Pipeline Model Space World Space Eye/Camera Space Screen Space Model Transformations Viewing Transformation Projection & Window Transformation Viewing Transformations Projection: take a point from m dimensions to n dimensions where n < m There are essentially two types of viewing transforms: Orthographic: parallel projection Points project directly onto the view plane In eye/camera space (after viewing tranformation) : drop z Perspective: convergent projection Points project through the origin onto the view plane In eye/camera space (after viewing tranformation) : divide by z Parallel Projections We will deal only with Orthographic (in this set of slides) Projection direction is parallel to projection plane normal Center of projection (COP) is at infinity Parallel lines remain parallel All angles are preserved for faces parallel to the projection plane Center of projection at infinity p1 p2 p1 p2 Projectors Points project orthogonally onto (i.e., normal to) the view plane: Projection lines are parallel Orthographic Projection x y z Projection Environment x y z The view plane is in the xy plane and passes through the origin The view direction is parallel to the z axis The eyepoint or camera position is on the +z axis, a distance d from the origin We will use a righthanded view system d Parallel Projection x y z What is (x, y, z)? A point in 3space projects onto the viewplane via a projector which is parallel to the z axis (x, y, z) (x, y, z) Parallel Projection x z (x, y, z) So z = 0, x = x Looking down the y axis: (x, y, z) Parallel Projection y z (x, y, z) So y = y Looking down the x axis: (x, y, z) Parallel Projection Thus, for parallel, orthographic projections, x = x, y = y, z = 0 So, to perform a parallel projection on an object,...
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This note was uploaded on 03/02/2012 for the course C S 455 taught by Professor Jones,m during the Winter '08 term at BYU.
 Winter '08
 Jones,M

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