Method of Extracting 3D Axis of Tunnel Based on Minimum Bounding Box Algorithm

Abstract

The invention discloses a method of extracting a three-dimensional axis of a tunnel based on a minimum bounding box algorithm. The method comprises the following steps of: extracting point cloud slices of a lining ring by virtue of the minimum bounding box algorithm of the tunnel with variable-angle step length; then, fitting the extracted point cloud slices according to an oval or circular model to solve coordinates of a center, and performing smoothing processing on the tunnel axis by adopting a horizontal-curve second-order continuous and a longitudinal-curve second-order continuous method; and finally, obtaining high-precision three-dimensional central axis of the tunnel. The method disclosed by the invention has the advantages that the three-dimensional axis of a single targe structure is automatically extracted by utilizing three-dimensional laser scanning original-point cloud data based on the minimum bounding box algorithm; the method is high in precision, high in speed, and capable of being used in tunnel axis detection, diameter convergence extraction, production of orthoimages, and the like. Besides, the defect that the tunnel design axis or actually measured axis is needed to be pre-input in the conventional processing method can be avoided, so that the automation degree of the data processing is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of tunnel engineering measurement, and in particular relates to a method for extracting a three-dimensional axis of a tunnel based on a minimum bounding box algorithm. Background technique [0002] The central axis of the tunnel is a virtual curve at the center of the inner space of the tunnel parallel to its extension direction, which reflects the spatial posture and trend of the tunnel, and is the premise of extracting the longitudinal section of the tunnel. [0003] When using the total station to measure the three-dimensional axis of the shield tunnel, the traditional method generally uses the total station to measure multiple feature points of the lining ring section at a certain interval, and uses the circle fitting model to solve the central coordinate of the ring as the tunnel axis. In actual operation, it is necessary to manually carry out aiming and observation of measuring points on site, and the ...

AI Technical Summary

Problems solved by technology

The above algorithm does not take into account the twisting of the three-dimensional axis of the tunnel caused by tunnel bottom shear (settlement) or splicing, so it has a certain impact on the extraction of the tunnel diameter

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