Tunnels point cloud processing system V1.0 Instructions
Introduction
tunnel point cloud processing system V1.0 is a point cloud processing software for deformation monitoring of metro tunnel shield structure. The use of 3D laser scanning technology to obtain subway tunnel data is a discrete point cloud. With the help of this system, the acquired point cloud data can be displayed, the central axis of the tunnel can be obtained, and the section of the tunnel can be continuously intercepted according to the central axis, and the deformation of the tunnel can be analyzed according to the point cloud of the section. Through coordinate conversion, the point cloud data of the two phases can be compared and analyzed to monitor the deformation of the tunnel.
First, the software installation and registration
1. The software development environment and install the
software using the C # language based .Net4.0 development, you need to install to use in more than WindowsXP version environment. The installation process is shown in Figure 1. Follow the prompts to complete the installation.
Figure 1 installation process
2. Software Register Login
Register screen displays, you need to fill in your user name and password, as well as the correct registration code when you first open the software. As shown in Figure 2. Click Register and follow the prompts to complete the registration operation. The login window is shown in Figure 3. Fill in the username and password you filled in during registration, and click Login to enter the system interface.
Figure 2 registration interface
3 login screen
Second, the software main function
1. Tunnel Point Cloud filtered
raw point cloud data RIEGL VZ-400 scanner obtained subway tunnel as an example, which includes a tunnel wall, catenary, rail and other information. First, according to the characteristics of the tunnel shape, the point cloud is filtered and the tunnel wall is extracted. The specific process is as follows:
(1) First fit the central axis of the tunnel, and then continuously extract the tunnel section points along the direction of the central axis.
(2) Using the ellipse least squares fitting method, fit the extracted tunnel section points to an ellipse.
(3) The distance between the section point and the fitted ellipse is used as the threshold to filter the non-tunnel wall points to obtain the tunnel inner wall points. The principle of selecting the threshold is to ensure that as many points on the inner wall of the tunnel are extracted as possible, but also to avoid noise points such as appendages connected to the inner wall of the tunnel. Considering that the inner wall of the tunnel is not an ideal smooth surface, the software defaults the threshold to 3cm.
The central axis should theoretically be located at the center of symmetry of the section, but due to the existence of errors, there will actually be a deviation d between them. If d exceeds the set threshold, you need to follow the steps (1) and (2) to refit the central axis of the tunnel until d is less than the threshold.
Figure 4 Comparison before and after filtering
2. Tunnel Model Construction
The point cloud data section, using Archimedes pileare pair difference encrypted tunnel section for generating a tunnel section model, the overall model as shown in FIG 5 (a) Tunnel FIG 5 (b)
in FIG. 5 (a) (B)
3. deformation analysis
the cross-sectional model generated tunnel, the tunnel may be measured at any angle away from the axis point fitting distance d, and the two tunnel walls L., measurement and analysis section 6.
FIG 6 Measurement Analysis Section
4. The coordinate transformation
for comparison of the deformation of the different data may be utilized to mark the target cloud point is converted to the unified coordinate system.
The cross-section matching analysis
in a unified coordinate system, in accordance with the relationship between two adjacent sectional cloud point coordinate data, two data match the corresponding cross-section. And compare and analyze the deformation.
Third, the specific steps to achieve
the first step, the data preprocessing
1. Open the data
in FIG. 7, "Open Data" button in the main interface, click, find the point cloud original file path, is opened. Click the drawing in the model building module to display the point cloud data. You can rotate and zoom to observe the original point cloud data.
7 _ Open Data Data preprocessing
2. Modifications path
click Edit path file processing program can be customized into the file folder.
3. Segmentation preprocessing
The function of "segmentation preprocessing" is realized, and a point cloud of a certain distance from the scanning instrument is intercepted from the original data of a station. The distance parameter is set above the button. The default value is 20 meters.
4. Suction
"Suction" function is set for the uneven distribution of point cloud density due to the scanning distance of one station of scanning data. It is divided into two modes: uniform suction and proportional suction.
5. The tunnel edge
"tunnel edge" function realizes the search for the edge point of the tunnel. And generate two files of tunnel edge point and axis point.
6. Generate axis
generating axis function, click the "Generate axis" button, open the resulting file axis point, generating axis fitting file.
A second step of model building
8 _ model construction section taken press axis
7. Press section taken axis
click "press section taken axis" button to open the generated "* .ZXD" file, the process performed in section taken axis.
8. The ellipse fitting
click "ellipse fitting" button to open the generated ellipse point "* .TYD" file, perform ellipse fitting procedure.
Open file ellipse fitting 9
9. tunnel wall data generating
click "data generation tunnel wall" to open the tunnel section point file " .DMD", performed to generate data tunnel wall, the tunnel wall to give point file ( .SDMD) and elliptical tunnel Point file (*.STYD).
Figure 10 Open the tunnel section point file
10. The model generating radial
again click "ellipse fitting" button, select below, to open a tunnel ellipse point file (generated .STYD), then click the "Generate radial model" button to open a file generated tunnel wall point ( . SDMD) as shown in the figure. Generate radial modeling file ( .JXM) and radial orientation file ( .JXF).
Figure 11 (a) Open the tunnel ellipse point file ( .STYD) (b) Open the tunnel wall point file ( .SDMD)
11. Analysis of Radial
click "radially Analysis" open radially generated modeling files (* .JXM), below the display modeling.
Figure 12 (a) Radial analysis section (b) Open the radial modeling file (*.JXM)
12. coordinate transformation model
click "model coordinate transformation" button, select the default four-parameter button. As shown in the figure, open the conversion parameter file (target coordinate file), and then open the model file to be converted (*.JXM). The converted model coordinate file is obtained by calculation.
Figure 13 (a) Open the coordinate conversion file (b) Open the coordinate conversion data file
The third step, deformation analysis
comparison measurement section 13. The model
respectively click "section model", "model comparison section" button to open the generated (.JXF) file. Then select the corresponding section, click the corresponding "section measurement", "compare section measurement" button. Realize the section measurement function.
Figure 14 (a) Comparison section measurement (b) Section measurement result display
14. The model matching section measured
at the point where two elliptical cross section of the model to be matched is read (* .JXF), to open a tunnel has been subjected to coordinate a unified model. As shown in (a),
then click the axis matching button. Establish the association of the corresponding section model. As shown in Figure (b), click on the corresponding cross-section model for comparative analysis.
Figure 15 (a) Splicing display of tunnel model (b) Section matching measurement
IV Conclusion
according to Zhengzhou Metro tunnel test data, to the relative deformation monitoring requirements indicators. After 8 months of programming and design, the tunnel point cloud processing system V1.0 was launched. This software mainly solves the tunnel wall point cloud extraction and analysis function in the tunnel point cloud processing. Combined with the tunnel deformation monitoring requirements, it shows the deformation of the tunnel section and the overall deformation of the tunnel. Provide technical support for the safe operation of subway tunnels. There are still imperfections in the software development, and suggestions are welcome. Contact: [email protected].
Technology Opening Project of China Railway Tunnel Survey and Design Institute Co., Ltd.