Basics of the stereo-3D imaging method, illustrated with the simple case of parallel and calibrated camera pair with optical centers at C₁ and C₂, respectively, separated by the baseline distance of L. The point, P, in the 3D world is imaged at points A and B on the left and the right cameras, respectively. A′ on the right image plane corresponds to the point A on the left image plane. The distance between B and A′ on the epipolar line is called the binocular disparity, ∆, which can be shown to be inversely proportional to the distance of the point P from the baseline [1].