## 4.2. Projections.

Mapping 3-D co-ordinates to a 2-D screen => some kind of
transformation. If we only use the (x,y) of (x,y,z) then this
is an orthographic projection. Not realistic.

Orthographic projection is one of the parallel projections. The other is

oblique. The relative length information is still preserved but angles are not.

For the parallel projections the centre of projection is at
infinity i.e the rays forming the object are parallel. If the
Centre of Projection (C.O.P) is not at infinity then the
projection is a perspective projection.

For // projection => direction of projection.

For perspective projection => C.O.P.