- Consider two images of a scene obtained by the same camera from different position and orientation.
- The images of the points at infinity,
**the vanishing points**, are not affected by the camera translation, but are affected only by the camera rotation . - Consider a scene line with vanishing point in the first view and in the second.
- The vanishing point
has a direction
in the
first cameras Euclidean frame, and, similarly, the vanishing
point
has a direction
in the second
cameras Euclidean frame. We have
- The directions are related by
- Hence, the rotation matrix can be computed from two such corresponding directions provided we know .

Subhashis Banerjee 2008-01-20