Camera calibration mark center coordinate extraction method

Abstract

The invention discloses a camera calibration mark center coordinate extraction method. The calibration mark center coordinate extraction method applies the following steps that (1) an image is divided into areas, and different parameters are set for different areas to perform Hough circle detection so that a circular mark image is obtained; (2) the inscribed polygon of the circular mark image in the step (1) is extracted; (3) Hough linear detection is performed in the inscribed polygon, and the intersection point coordinates of straight lines are extracted; and (4) reliability of the intersection point coordinates is detected, coordinates of the center of circle obtained in the step (1) are compared and a threshold is set, intersection points outside the threshold are deleted, the intersection points of the straight lines within the threshold are obtained, and the mean value of the intersection points of the straight lines is obtained and calibration mark center coordinates are obtained. The image is divided into areas, the parameters of different areas are respectively set to perform circle detection in the circle detection process, and the mean value is obtained according to the intersection point coordinates of the straight lines and the mark center coordinates are obtained so that extraction precision of the center coordinates is greatly enhanced.

Description

technical field [0001] The invention relates to the field of camera calibration, in particular to a method for extracting the center coordinates of a camera calibration mark. Background technique [0002] In modern measurement, non-measurement digital cameras have the characteristics of low cost, easy to carry, and simple operation, making them more and more widely used in the fields of aerial measurement, part inspection, and three-dimensional reconstruction. However, the internal orientation elements of ordinary non-measurement digital cameras are unknown and the distortion difference is relatively large, so they cannot be directly applied to photogrammetry. It is necessary to perform camera calibration on the captured photos to obtain the internal orientation elements and distortion coefficients of the camera. The extraction of the center coordinates of the logo image is a very important step. [0003] The calibration mark is composed of a simple circle and a straight li...

AI Technical Summary

Problems solved by technology

[0009] 1. The method of artificially enhancing a certain color component is not accurate when detecting a circular feature block; and when calculating the precise center coordinates of the mark, use the symmetry principle to find the center of the circular feature block to obtain the center coordinates of the mark. This method requires The obtained features must be fast and accurate, and the calculation process is also somewhat complicated

[0010] 2. The method of obtaining the initial position through direct linear transformation first detects the straight line during detection. In the actual environment, there is a lot of noise in the straight line, resulting in low detection accuracy

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