1. College of Civil Engineering,Zhejiang University of Technology, Hangzhou, Zhejiang 310023, China
2. Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province, Hangzhou, Zhejiang 310023, China
Abstract：Based on the video of surveillance camera and digital image processing, a method to characterize the displacement of structural position feature points was designed. Firstly, the circular target is placed on the structure. The template matching method is used to detect the initial image coordinate region of the circular target, and the region of interest(ROI) is cut out; Then use Otsu method to determine the binarization threshold of the region, extract the coordinates of the target contour points, use the least square method to fit the contour into an ellipse, and obtain the coordinates of the center of the ellipse and the size of the long and short axis. The ratio of the diameter of the circular target to the major and minor axis is the conversion coefficient η; The product of the change of the ellipse center coordinate and the conversion coefficient is the displacement of the structure in the actual corresponding coordinate direction. The experimental results shown that the relative error of this method was less than 3% in the horizontal and vertical displacement loading experiments which compared with the high-precision displacement meter. And it can realize millimeter displacement monitoring and accurately characterize the displacement change of the corresponding characteristic points of the structure.
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2023, Vol. 44 
