- But note that other choices for the value of the third
component are equally valid. Kanatani [Kanatani 1992] sets the
third component to be equal to the focal length of the camera, and
this has advantages which he describes.
- Ideal points have their third component equal to zero
by convention. It is possible to define a coordinate frame in
which an ideal point has a non-zero value in its third component,
but this is rarely encountered so it is not worth digressing to
discuss it in this short appendix.
- The definition of which elements are dual to one another
depends on the projective space - points are dual to lines on the
projective plane. However,
points are dual to planes, and lines are dual to lines, in
Fri Nov 7 12:08:26 GMT 1997