[Hill: 379-385. Foley & van Dam: p. 239-242]
View Volumes
View volumes are used for:
- clipping objects which will not project onto the image
- restricting the domain of z for visibility calculations
A perspective view volume:
An orthographic view volume:
![](img/orthvvol.gif)
Clipping operations could be carried out directly based upon the view
volumes defined, but is simpler using a canonical view volume. The
coordinate system is referred to as the normalized device coordinate
system or NDCS.
OpenGL Canonical View Volume
![](img/oglvvol.gif)
The transformation from VCS to NDCS can be
conveniently viewed as part of the projection transformation, as we shall
see shortly.
![](img/vvolcs.gif)
Viewport Transformation
- NDCS to DCS
- simple translate and scale