A linear approach for determining camera intrinsic parameters using tangent circles
A linear approach using three tangent circles is proposed for determining the intrinsic parameters of cameras. A projected circle can be used to compute the image coordinate of the centre of each tangent circle and to find the points in the image corresponding to the tangent points associated with the images of the centres of the projected circles. The vanishing point can be determined along the circle diameter according to the invariance of the cross-ratio. Solving the equations for the tangent lines produced a curve in the image of the tangent point and its corresponding point. The other vanishing point can be obtained from the intersection point of the two tangent lines. With vanishing points in two orthogonal directions, the intrinsic parameters can be linearly determined. The results of our experiments show that this approach is effective and highly precise.
camera intrinsic parameters tangent circle vanishing point circular points