Tunnel lining crack width measuring method and device

Abstract

The invention relates to a tunnel lining crack width measuring method, which comprises the follow steps of: (1) picking up crack images through a digital camera and measuring pickup distance through a laser distance measuring instrument; (2) selecting a region required to be measured on the picked images and converting selected region images into gray level images; (3) determining the threshold value of the gray level images selected in the second step, cutting binary image cutting, and obtaining a target region; (4) extracting a white region only comprising crack in the target region; (5) extracting the edge of the crack by a sub pixel method, and obtaining sub pixel level edge images; (6) circulating the pixel width of the crack by a minimum distance method; (7) circulating the actual width of the obtained crack according to the calibration proportion of the predetermined actual pixel size and the image pickup distance; and (8) storing the obtained actual width data into a crack data base. Compared with the prior art, the tunnel lining crack width measuring method has the advantages of low cost, high speed, convenience, high precision and the like.

Description

technical field [0001] The invention relates to a tunnel lining crack measurement technology, in particular to a method and device for measuring the width of a tunnel lining crack. Background technique [0002] Quantification of defects such as cracks has always been the goal of non-destructive testing. With the advancement of detection technology, the traditional method of measuring the crack width by human eyes or using a simple instrument such as a reading magnifying glass to estimate, due to the high subjectivity of its personnel, and low accuracy and efficiency, will Gradually replaced by new methods. With the rapid development of computer technology and the continuous improvement of related theories, digital image processing technology has been widely valued in many application fields and has achieved significant pioneering achievements. The photogrammetry technology based on digital image processing has penetrated into the fields of civil engineering such as crack w...

AI Technical Summary

Problems solved by technology

In the tunnel, for images of high-level cracks that cannot be touched, the process of hand-held contact acquisition is cumbersome

However, images taken at long distances are sensitive to noise and light, which seriously affects image quality and makes subsequent image preprocessing difficult and complicated.

The area ratio of cracks in long-distance images is much smaller than that in contact images, leaving a large area of ​​complex and changeable background images, coupled with the defects of some edge detection methods, making close-up The edge extraction method for medium and wide cracks is not applicable, and a suitable new method needs to be found

In addition, unlike the contact measurement with a fixed distance, the randomness of the location where the crack occurs leads to the randomness of the shooting distance. It is necessary to find a new calibration method to replace the traditional fixed-distance calibration

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