Exploration On Acquisition Method Of Bridge Deck Holographic Deformation By Improving Image Plane Registration

This paper relies on the project of National Natural Science Foundation of China(NSFC)"Exploring the deduction method of bridge holographic deformation and structural state based on image contour stack difference analysis"(51778094).Testing the holographic image data acquisition of steel truss-concrete composite beams under graded loading.The three-dimensional data model of steel truss-concrete test beam based on image recovery is completed,and the holographic deformation value of the test Girder bridge panel is obtained.The main research contents are as follows:1.Analyzing the theoretical basis of data model restoration based on multi-view stereo images,aiming at the process of data model restoration,a smart phone was used to take a small-scale model bridge's data image,and the digital model of the model bridge was obtained.The overall size of the model bridge was consistent and the detailed characteristics of the model bridge could be clearly displayed.2.In order to improve the efficiency of data processing,a point cloud registration method based on rigid transformation of feature region is proposed,and the surface region with obvious vector fluctuation of three-dimensional data model is recovered in the data image,and multiple intersection points,polygons and intersection lines and bump area points are selected in the identified Polygon area.Based on these characteristics,rough registration of data model is carried out with feature constraints.Based on the location parameters of rough registration point cloud model,the Euclidean distance square sum between matching points is defined as the objective function.The accuracy of data model registration is improved obviously by iterating the objective function to the convergent data model registration under two conditions.3.The experimental study on digital image data acquisition of steel truss-concrete test beams has been completed in the laboratory.The data models of test beams under different deflection and deformation states are restored before and after damage.The holographic deformation data of bridge deck under different load states are obtained by restoring the data models of test beams based on stack difference analysis.Aiming at 331.2 m span real bridge,the shape data collected by vehicle-borne laser scanning equipment are applied to engineering research.Based on the construction characteristics of the data model at the expansion joint position of long-span real bridge pier,the registration of shape data model under different ambient temperatures is completed by using the rigid transformation registration method based on feature region,which improves the registration accuracy of the model and extracts the effective deflection.At the same time,the deflection values of the bridge under different temperature loads are obtained.