Extracting the Centers of Dual Linear Structured Light Stripes for Seam Measurement
DING Zujiao1, LI Shuanggao1, ZHAI Jianjun1, LI Dong2
( 1. College of Mechanial and Electrical Engineering, Nanjing University of Aeronautics and Astronautics,
Nanjing 210016, China;
2. AVAC Hongdu Aviation Industry Group Ltd., Nanchang 330024, China)
Abstract：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.
2017, 
