Method for adaptively detecting chessboard sub-pixel level corner points

A method for adaptively detecting chessboard sub-pixel level corner points, comprising the following steps:

• 1) setting marks:
• setting marks on a chessboard to mark position of an initial unit grid;
• 2) shooting an image:
• using a camera to collect an image of a chessboard calibration target, and conducting preliminary image processing;
• 3) detecting the marks:
• detecting pixel coordinates of the marks set in step 1) by a mark detection algorithm;
• 4) using the marks:
• calculating pixel coordinates of four corner points of the initial unit grid defined by the marks according to the pixel coordinates detected in step 3), calculating sub-pixel level corner point coordinates by iteration and conducting verification;
• 5) expanding outwards:
• calculating a homography matrix H according to the sub-pixel level corner point coordinates of the four corner points in step 4) and world coordinates thereof in a world coordinate system;
• multiplying the homography matrix H with world coordinates of four corner points of an adjacent unit grid of the marked unit grid in the world coordinate system to calculate sub-pixel level corner point coordinates of the other two unknown corner points of the adjacent unit grid;
• 6) adaptively adjusting:
• counting side lengths of the adjacent unit grid obtained in the process of expanding outwards in step 5), and dynamically adjusting size of an iteration window for calculating sub-pixel level corner points to increase accuracy of sub-pixel level corner point detection.