Volume XLII-2/W7
Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLII-2/W7, 353-360, 2017
https://doi.org/10.5194/isprs-archives-XLII-2-W7-353-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLII-2/W7, 353-360, 2017
https://doi.org/10.5194/isprs-archives-XLII-2-W7-353-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.

  12 Sep 2017

12 Sep 2017

AUTOMATIC MONITORING OF TUNNEL DEFORMATION BASED ON HIGH DENSITY POINT CLOUDS DATA

L. Du1,2,3, R. Zhong1,2,3, H. Sun1,2,3, and Q. Wu1,2,3 L. Du et al.
  • 1Beijing Advanced Innovation Center for Imaging Technology,Capital Normal University, Beijing 100048, China
  • 2College of Resources Environment and Tourism, Capital Normal University, Beijing 100048, China
  • 3Key Lab of 3D Information Acquisition and Application, Capital Normal University, Beijing 100048, China

Keywords: Subway Tunnel, Deformation Monitoring, Point Clouds, Central Axis, Cross Section, Random Sample Consensus, K- Neighbors

Abstract. An automated method for tunnel deformation monitoring using high density point clouds data is presented. Firstly, the 3D point clouds data are converted to two-dimensional surface by projection on the XOY plane, the projection point set of central axis on XOY plane named Uxoy is calculated by combining the Alpha Shape algorithm with RANSAC (Random Sampling Consistency) algorithm, and then the projection point set of central axis on YOZ plane named Uyoz is obtained by highest and lowest points which are extracted by intersecting straight lines that through each point of Uxoy and perpendicular to the two -dimensional surface with the tunnel point clouds, Uxoy and Uyoz together form the 3D center axis finally. Secondly, the buffer of each cross section is calculated by K-Nearest neighbor algorithm, and the initial cross-sectional point set is quickly constructed by projection method. Finally, the cross sections are denoised and the section lines are fitted using the method of iterative ellipse fitting. In order to improve the accuracy of the cross section, a fine adjustment method is proposed to rotate the initial sectional plane around the intercept point in the horizontal and vertical direction within the buffer. The proposed method is used in Shanghai subway tunnel, and the deformation of each section in the direction of 0 to 360 degrees is calculated. The result shows that the cross sections becomes flat circles from regular circles due to the great pressure at the top of the tunnel