The epipole is the point of intersection of the line joining the optical centres, that is the baseline , with the image plane. Thus the epipole is the image, in one camera, of the optical centre of the other camera. The epipolar plane is the plane defined by a 3D point M and the optical centres C and C '. The epipolar line is the straight line of intersection of the epipolar plane with the image plane. It is the image in one camera of a ray through the optical centre and image point in the other camera.
All epipolar lines intersect at the epipole.
Thus, a point x in one image generates a line in the other on which its corresponding point must lie. We see that the search for correspondences is thus reduced from a region to a line. The epipolar line along which the corresponding point for must lie. The essential matrix and the fundamental matrix To calculate depth information from a pair of images we need to compute the epipolar geometry. In the calibrated environment we capture this geometric constraint in an algebraic representation known as the essential matrix.