Patent ID: 11900634
Assignee: PENG CHENG LABORATORY
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 0:
1. 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.