| Due to the complexity and diversity of the slope deformation mechanism,there is no mature deformation monitoring method and data processing theory not yet.BIM technology combining 3D laser scanning with reverse modeling has the characteristics of visualization and information,and supports data integration and design analysis.In order to comprehensively and accurately monitor the deformation of the retaining wall slope,the 3D laser scanner is used to collect the data in the study area,and the method of reverse modeling is used to establish the high-precision retaining wall slope point cloud model and 3D surface model.The target-center fitting algorithm based on the target contour point cloud group is used to determine the coordinates of the center point of the plane target,and the accuracy of the point cloud model is analyzed by comparing with the prism-free measurement result of the total station.The gravity method is used to extract the coordinates of feature point from the point cloud model,and the maximum displacement and deformation trend of the retaining wall slope are obtained by the comprehensive deformation analysis method.The main research contents of this paper are as follows:1.The target object is scanned by a 3D laser scanner,the sources of error in the stage of data collection and processing is analyzed,and the related measures of error control are proposed.2.A method of reverse modeling using point cloud data acquired by ground 3D laser scanning is research.The registration precision is analyzed by the comparison method.The texture information is given to the point cloud model based on the texture mapping imaging principle.The point cloud filtering is performed by the human-machine interactive denoising method.The point cloud simplification method is performed by the experimental contrast method.3D reconstruction based on the streamlined point cloud model is researched by the Geomagic Studio software.3.A method of evaluating accuracy of point cloud model is studied.Firstly,the target-center fitting algorithm based on the target contour point cloud group is proposed to determine the coordinates of the center point of the plane target.Secondly,the seven-parameter conversion method converts the target-center coordinates to the total station reference coordinate system,finally,accuracy check by comparison with the total station-free prism measurement results.The results show that the accuracy of the 3D model acquired by the method of reverse reconstruction meets the requirements of the specification and can be used for deformation monitoring.4.A method of extracting the coordination of monitoring point was proposed.For the traditional monitoring method,the number of monitoring points is limited,and the deformation of the undisposed monitoring point area cannot be obtained.A method of extracting characteristic parts from the point cloud model and obtaining the coordinates of monitoring points by the gravity method is proposed.5.deformation analysis methods is researched.The 3D deviation chromatogram is obtained by using the method of model comparison.The displacement of the monitoring point was obtained by the monitoring point displacement calculation method.Fitting the scatter to the feature line based on the least squares polynomial fitting method of MATLAB software,the displacement and the trends of characteristic part was obtained by the characteristic line contrast method.The feasibility analysis of the proposed method is carried out through a set of physical deformation simulation tests.The results show that the displacement obtained by the monitoring point displacement calculation method is more accurate than the model comparison,The comprehensive deformation analysis method based on points,lines and planes can be used for deformation analysis. |
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