These canonical view volumes are shown in Fig. 6.45.
Our strategy is to find the norniuiizing transformations NW and N’, that transform an
arbitrary par.allel- or perspective-projection view volume into the parallel and perspective
canonical view volumes, respectively. Then clipping is performed. followed by projection
into 2D. via the matrices in Section 6.-1. This strategy risks investing effort in transforming
points that are subsequently discarded by the clip operation. but at least the clipping is easy
to do.
Figure 6.46 shows the sequence of processes involved here. We can reduce it to a
tl'd.nSf0rn1-Clip——Lral1sfortn sequence by composing steps 3 and 4 into a single transformation