Polygonization of Point Cloud of Tunnels Using Lofting Operation.

This paper proposes a novel method for polygonizing scanned point cloud data of tunnels to feature preserved polygons to be used for maintenance purposes. The proposed method uses 2D cross-sections of structures and polygonizes them by a lofting operation. In order to extract valid cross-sections from the input point cloud, center lines and orthogonal planes are used. Center lines of the point cloud are extracted using local symmetry analysis. In addition, this research segments a point cloud of a tunnel into lining concrete, road, and other facilities. The results of applying the proposed method to the point clouds of three types of tunnels are demonstrated, and the advantages and limitations of the proposed method are discussed.