Closed curved surface deformation detecting method based on three-dimensional laser point cloud

Abstract

The invention discloses a closed curved surface deformation detecting method based on three-dimensional laser point cloud. The method comprises steps of preprocessing closed curved surface three-dimensional laser point cloud data; extracting a central line of the closed curved surface, performing central line extraction on the closed curved surface, processing central line extraction of the pointcloud by means of an iterative algorithm; wherein an initial value adopted by the iterative algorithm is the designed central line of the closed curved surface; intercepting a point cloud section; executing a section deformation detecting method based on geometric fitting; performing automatic comparison of curved surface data, comparing the sections of multiple point clouds in different periods at the same mileage, and obtaining deformation information of the section at the same mileage in different measurement periods; using a central point which is obtained through fitting of each section as a reference, and performing comparative analysis on the multiple cloud points in different periods in each direction in a plane where the section exists; and setting the sparse degree of the plane with the section in each direction through a parameter, wherein a deformation detecting algorithm supports batch section comparative analysis operation. The closed curved surface deformation detectingmethod has an advantage of supplying important original data for project safety argumentation.

Description

technical field [0001] The invention relates to the field of tunnel deformation detection, more specifically, it is a closed curved surface deformation detection method based on three-dimensional laser point cloud. Background technique [0002] In the construction and operation and maintenance stages of water conservancy project tunnels, railway mountain tunnels, and urban subway tunnels, there is a demand for deformation detection of closed surfaces. Effective deformation detection can use professional equipment and methods to continuously observe the deformation phenomenon of the closed body, accurately measure the spatial state and time characteristics of the shape, size and position of the closed body, and detect the deformation area beyond the allowable value Give timely warning. [0003] Deformation detection methods at home and abroad can be mainly divided into two types: contact detection and non-contact detection; contact detection requires manual installation of m...

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Problems solved by technology

[0003] Deformation detection methods at home and abroad can be mainly divided into two types: contact detection and non-contact detection; contact detection requires manual installation of monitoring instruments at different positions on the inner wall of the tunnel or tunnel, so as to obtain the deformation information of the closed surface; the installed Monitoring instruments include extensometers, Bassett convergence measurement systems, etc. These methods can directly measure the deformation of specific positions and sections of the tunnel, but the cost of manpower and financial resources is extremely high, the monitoring period is long, and the space of the detected object is limited. Size, internal environment, etc.

[0004] Non-contact detection can be divided into three categories: laser ranging technology, digital image processing technology and optical fiber sensing technology; optical fiber sensing technology is limited by the material of the optical fiber, and is not suitable for geotechnical engineering where the deformation is too complicated; and the current optical fiber The resolution can only reach the meter level, which is a big limitation for high-precision deformation detection; and digital image processing technology has high requirements for equipment and personnel for fine image processing, and this method has not yet formed a systematic detection system. Engineering application is relatively difficult

[0005] In comparison, laser ranging technology is the most suitable non-contact detection method for tunnels and tunnel engineering. Among them, 3D laser scanning technology is the most advantageous; Efficiently obtain 3D information such as point cloud data and digital images of tunnels at different time periods; however, the existing research methods only focus on general modeling of 3D point clouds, and there are no scanning modeling and deformation detection methods for closed surfaces

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