A Fast and Accurate Algorithm for Chessboard Corner Detection

The authors point out the limitations of SUSAN corner detector in detecting chessboard corner, then describe an improved SUSAN(smallest univalue segment assimilating nucleus) detector algorithm for detecting chessboard corner on the basis of symmetrical geometry structure of USAN (univalue segment assimilating nucleus) area. And the algorithm has been applied to the chessboard images on real photos. The improved algorithm can quickly detect corner from real photos shot from every angle. The theory of detecting corner at sub-pixel level is orthogonal vector theory, that is, vector from the corner to its adjacent area pixel point should be vertical to gray grads of the adjacent area pixel point. In order to get the coordinate of corner at sub-pixel level, we establish the neighboring area equation and solve it via iterative method, and propose to check its validity according to cross ratio invariability in perspective projection.