 Suppose such world point P whose corresponding image points are P1(u1,v1) and P2(u2,v2) respectively on the left and right image plane.Assume two cameras are in the same plane, then y-coordinates of P1 and P2 are identical, i.e.,v1=v2.According to trigonometry relations,

formula_1

formula_2

formula_3

where(xp, yp, zp) are coordinates of P in the left camera's coordinate system, f is focal length of the camera.