Research On Light Stripe Thinning Method In Seam Measurement Using Structured Light

The 3D vision detection technology based on line structured light has a wide application prospect in aerospace,ship and other fields due to its significant advantages,such as fast detection speed,noncontact between the testing equipment and the surface to be inspected.In structured light measurement system,light stripe thinning is a key step in image processing since its precision will directly affect the measurement accuracy of the system.In this paper,taking the structure light measurement technology applied to seam measurement as the research's object,a thinning method based on adaptive Fourier fitting algorithm is proposed so as to improve the processing speed of light stripe thinning and measurement accuracy.Mainly from the following aspects of research:1)Aiming at reducing the noise in the light stripe image better,the existing wavelet threshold denoising method is improved,which can keep the edge information of the light stripe while suppressing the noise and reduce the influence of noise on the thinning precision of the light stripe.The way to extract the seam measurement area is determined by the distribution characteristics of light stripe in the image and this adaptive decision can improve the thinning efficiency.2)Aiming at extracting the center position of light stripe in dual structured light seam measurement system better,a new method of center line abstraction from light strip based on adaptive Fourier fitting algorithm has been proposed.Since the gray scale of dual-line-structured light cross section is periodically distributed,the normal direction of each point on skeleton lines is calculated by using the mean square of gray scale gradient.Then,the normal width of each structural light stripe can be calculated by using adaptive threshold method,and remove the light overflow point at the seam.Finally,Fourier fitting is used to finish the light stripe thinning.3)Based on the existing evaluation methods of thinning precision,the precision evaluation methods based on corresponding coefficient for linear light stripe is proposed,as well as the precision evaluation methods based on the center distance for cure light stripe.Furthermore,different measurement schemes for the two different seam measurement pattern—steps and gaps are designed.Based on the above theoretical research,experimental results show that: compared with the existing methods of light stripe thinning,the refine precision and seam measurement accuracy based on adaptive Fourier fitting algorithm is much better.