Research On Bridge Spatial Coordinate Measurement Method Based On Coplanar Feature Image

Photogrammetry is a scientific technique that uses the image of the object to reconstruct the spatial position and three-dimensional shape of the object.Its non-contact,high precision and low cost features are widely used in the field of bridge health monitoring.This paper uses photogrammetry to shoot bridges and other targets,and solves the position and posture of the camera at the time of shooting through photogrammetry based on coplanar feature images,and then finds the spatial coordinates of the target points on the bridge,providing reliable data for bridge health monitoring.The main contents of this paper are as follows:1.Based on the analysis of the constellation relationship when the camera is imaging,aiming at the shortcomings of the camera in the bridge shooting method,a photogrammetry method(Exchange-position Photogrammetry,E-P photogrammetry)is proposed.This method fixes the control target outside the bridge,places the camera on the bridge,and shoots along the direction of the bridge to solve the camera position and posture at the time of shooting,that is,it can measure the spatial coordinate information of points on different cross-sections of the bridge.2.The imaging model of the E-P method is simplified,and all control targets are placed in a feature plane to form a camera imaging model based on coplanar features.This model reduces the difficulty of setting and measuring the control target under the condition of meeting the requirements of photogrammetry,and makes the choice of photogrammetry scheme more diverse.3.A camera imaging model(Coplanar feature point-line camera mode,CFPL model)integrating coplanar feature points and feature lines is proposed.The model uses coplanar points and coplanar lines to measure the azimuth elements of the camera,fusing the ease of measurement of points and the high robustness of straight lines,thereby improving the accuracy of the solution.Through simulation data,the thesis studies the error distribution law of the camera imaging model based on coplanar features when calculating the orientation elements of each photo.4.According to the camera’s internal azimuth elements solved by Zhang Zhengyou’s camera calibration method,the spatial coordinates of each point on the cross section of the bridge were measured using the EP photogrammetry method based on the image coplanar features,and the accuracy analysis was carried out.The morphological measurement of the cross section of the bridge;at the same time,the spatial coordinates of the points on the track are also measured,which verifies the feasibility and applicability of the model for the high-precision measurement of the spatial coordinates of the cross section of long objects.