Camera calibration method based on a flexible spliced pattern of equilateral triangles

• Published in: 2013 Chinese Automation Congress pp. 250 - 254
• Main Authors: Wang Xiuping, Bai Ruilin, Guo Xinnian
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.11.2013
• Subjects: Calibration; camera calibration; Cameras; circular point; Equations; equilateral triangle; Mathematical model; planar pattern; Three-dimensional displays; vanishing point; Vectors
• DOI: 10.1109/CAC.2013.6775737

This paper focuses on the study of 2D calibration method, involving a new planar pattern based on equilateral triangles, and a new camera calibration algorithm using the new pattern. Firstly, three triangles with same size and same color on the same plane, which side length can be any size, are spliced together to form a large equilateral triangle. Secondly, more than three pattern images are captured from different orientation. Thirdly, sub-pixel coordinates of six corners are extracted from each pattern image. Then, using perspective geometry theory and the geometric characteristics of triangle template, more than ten vanishing points are calculated out, vanishing line is fitted out according to them, and the image coordinates of circular points are deduced. Finally, all the five intrinsic parameters can be determined linearly according the coordinates of circular points. Experiments with simulated data as well as with real images show that the new algorithm is robust and accurate. The integral calibration precision of this method can reach about 2% comparing with Zhang's method. Equilateral triangle pattern the method used is easy to access, and easy to build in the industrial field, and its measurement also need not know in the calibration process. So this method with higher precision has a good practical value.