COMP410 Projection

what are the three elements required for viewing

one or more objects, a viewer with a projection surface, projectors that go from objects to the projection surface.

the default orthographic viewing

vieweing volume from (-1,-1,1) to (1,1,-1)

and surface at z = 0

there are only two projections actually

everything else is a matter of how the projection plane is oriented with respect to the object

and they are parallel and persepective projections

actually parallel projection is a

limit of perspective projection

oblique projection

special case of parallel projection

angles in faces parallel to projection plane are preserved while we can still see “around” side.

default orthographic projection matrix

as z is set to zero

simple perspective projection matrix

projection normalization

to use a common pipeline (to just set z = 0), we can convert all projections to orthographic projection with the default view volume.

this strategy allows a single pipeline for all types of projections as well as efficient clipping.

normalization of orthographic viewing