Aiming at extracting the center position of light stripe in dual structured light seam measurement system

a new method of sub-pixel center line abstraction from light strip based on adaptive threshold and Fourier fitting has been proposed. According to the gray scale of optical cross section subjects to periodic distribution

in the first step

the proposed approach gets the initial position of strip center by skeleton thinning approach. Then

the normal direction of each point on skeleton lines is obtained by using the mean square of gray scale gradient. It uses adaptive threshold method to get the normal width of each structured light strip. Finally

by doing Fourier fitting job using the gray scale within the normal width

the peak value of the fitting curve could be obtained

and the center line as well. The experimental results show that the average distance between the extracting corners and the line fitted by the extracting centers is only 0.1182 pixels and 0.1428 pixels

which is better than the skeleton thinning method and Gauss fitting method

meanwhile the method can improve the accuracy of center line extraction from strip-structured light

the seam measurement precision can reach 0.04mm.