Vertical Deformation Monitoring Method Based on Monocular Vision and Near-Infrared Targets
To satisfy the requirements of all-weather,high-precision,and online deformation monitoring of large facilities such as bridges and tunnels,a vertical deformation monitoring method based on monocular vision and near-infrared targets is proposed.Near-infrared target lights are installed at several measurement points on tested structures.A center positioning method based on least-squares ellipse fitting is used to automatically track and determine the center image coordinates of the near-infrared target light spot.Subsequently,the actual vertical deformation of the measurement points on a tested structure is calculated using the imaging geometric relationship based on the true elevation angle.The indoor accuracy verification experiment determined the maximum indication error of this method to be 0.043 mm at a distance of 8.457 m.In the deformation monitoring application test of a certain track bridge,the 24 h vertical deformation monitoring results are highly consistent with the subway operation time.Also,the vertical deformation is within the range of-4-6 mm under the effect of subway loads,indicating that this method can be applied to all-weather,high-precision,real-time,and online deformation monitoring of actual engineering structures.
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