Processing And Analyzing The Point Cloud Data Based On The Curve Fitting Theory

Three-dimensional laser scanning technology has the characteristics of high automation, high-speed, high-precision, high-density adaptability and high operational reliability. A lot of point cloud data of measured surface can be got with three-dimensional laser scanning technology. How to deal with the point cloud data and applied it to actual project is particularly important. This paper got the fitting area of section by fitting the tunnel section curve, which was also applied to tunnel’s stability analysis. Following results were the main achievements here:1. Based on the curve fitting theory, this paper compared and analyzed several mature fitting methods, which mainly included Lagrange polynomial, least squares method, Bezier curve fitting, B-spline curve method, as well as comparing advantages and disadvantages of these methods. Three B spline curve fitting method could well show local characteristic of curve and the curve is more smooth, that was to say Three B spline curve fitting method was more suitable for the curve fitting of discrete point cloud data.2. Aiming at the problem of large amount of point cloud data, this paper used an improved three B spline method. Under the premise of the point cloud data of global and local shape fidelity, analysis of curvature distribution of point cloud data could identify key points and fit the key points.This method improved the operation efficiency and reduced the number of control points, which was more suitable for curve fitting of point cloud data on the intensity of the larger.3. Process and analysis of point cloud data about Yanshuigou tunnel. According to the characteristics of 3D laser point cloud data and the characteristics of tunnel cross-section, this paper achieved deformation analysis of surface. It used cubic B-spline curve fitting to fit the tunnel section and calculated the area. It compared the amount of change between the fitting area cross-sectional area and the design value stability through space sequence analysis methods. It compared and analyzed the area variation of the fitting area and the design through space sequence analysis methods. It compared and analyzed the area variation of the point cloud data of the same section in different period which determined the fitting accuracy and stability of the tunnel.