Obtaining Ellipse Common Tangent Line Equations by the Rolling Tangent Line Method

In the field of image processing and machine vision, it is sometimes necessary to obtain common tangent line equations and tangent point coordinates from ellipses. A rolling tangent line method was proposed to obtain the 4 common tangent line equations and 8 tangent point coordinates from two ellipses in this paper. The principle of this method is simple and it is easy to program on a computer. Use this method to process two ellipse targets in an image and the experiment results show that the 4 common tangent equations and 8 tangent point coordinates can be obtained in high precision and the maximum execution time is less than 0.1 s.