A 3D point is projected onto both image planes, to points and , which constitute a conjugate pair. The right pictures plot the epipolar lines corresponding to the point marked in the left pictures. Full size images When is in the focal plane of the right camera, the right epipole is at infinity, and the epipolar lines form a bundle of parallel lines in the right image. The epipole is rejected to infinity when . In this case, the direction of the epipolar lines in the right image doesn't depend on any more and all the epipolar lines becomes parallel to vector .
Epipolar lines form a bundle of parallel lines in both images.
Any pair of images can be transformed so that epipolar lines are parallel and horizontal in each image as in Fig. This procedure is called rectification .