CN111486797B - Automatic extraction method for transverse diameter of subway circular shield tunnel - Google Patents
Automatic extraction method for transverse diameter of subway circular shield tunnel Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
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Abstract
The invention belongs to the field of tunnel structure deformation detection, and relates to an automatic extraction method for the cross section diameter of shield tunnel three-dimensional laser scanning point cloud, which at least comprises the following steps: 1) acquiring point cloud of the inner wall of the shield tunnel by using a three-dimensional laser scanner; 2) generating a tunnel inner wall gray level image map by using the tunnel point cloud; 3) identifying the waist seam positions on two sides of the ring piece one by one; 4) automatically extracting points which are 0.813m away from the lower parts of the waist seams at two sides as diameter extraction references; 5) calculating the transverse diameter of the ring piece ring by ring according to the diameter extraction datum point; 6) and automatically detecting the diameter and extracting the quality loop by loop, performing manual intervention correction on the diameter with poor quality, and correcting the position of the datum point. The invention has the advantages that: by automatically extracting the diameter calculation datum point used in the traditional total station measurement from the point cloud, the extraction precision of the section diameter is improved, the problem that the common ellipse fitting extraction algorithm in the prior art is low in precision is solved, and the method can be better integrated with the total station measurement result.
Description
Technical Field
The invention belongs to the field of tunnel structure deformation detection, and relates to an automatic extraction method for the cross section diameter of a three-dimensional laser scanning point cloud of a subway shield tunnel.
Background
After the subway shield tunnel is built, the tunnel is often deformed due to the influence of a train and the action of external force, and the subway tunnel needs to be regularly measured in order to know the deformation. The measurement means commonly used at present are: diameter measurement datum points are arranged at positions with chord lengths of 0.813m below waist seams on two sides of a certain ring piece in the tunnel in advance, then a total station is adopted to conduct prism-free coordinate measurement on the diameter measurement datum points, and the distance between the datum points on the two sides is calculated to serve as a diameter measurement value of the tunnel ring piece.
With the gradual expansion of underground rail transit scale, higher requirements are provided for the rapid and accurate extraction of tunnel diameter and the detection of tunnel deformation, so that a three-dimensional laser scanning technology is gradually introduced into tunnel deformation measurement, three-dimensional laser scanning can rapidly acquire three-dimensional point cloud information of surrounding environments, and a new technical means is provided for subway tunnel detection. However, an effective method is lacked for extracting the tunnel diameter by processing the tunnel point cloud, and the currently common technical means is to slice and extract some ring point clouds, perform ellipse fitting on each ring point cloud, and extract the major axis of the ellipse as the current ring diameter measurement value. However, practical application shows that the difference between the diameter of the segment obtained by the point cloud ellipse fitting method and the diameter measurement result of the traditional total station is large, data are difficult to fuse, and the external coincidence precision cannot be guaranteed because the measurement method is different from the technical means.
Therefore, for the point cloud of the circular shield tunnel, a transverse diameter automatic extraction method which is similar to the diameter extraction method of the traditional total station and is convenient for data fusion is needed.
Disclosure of Invention
The invention mainly relates to a method for automatically extracting the transverse diameter of a three-dimensional point cloud of a circular shield tunnel. The method mainly comprises the following steps:
(1) acquiring shield tunnel point cloud information by using a three-dimensional laser scanner, wherein the shield tunnel point cloud information comprises point cloud coordinates (X, Y, Z) and a gray value p, the Y axis points to the vertical direction, the X axis points to the horizontal direction, and the Z axis points to the mileage direction;
(2) projecting the three-dimensional point cloud in the step (1) to a plane by using cylindrical tangent projection, and generating a complete tunnel inner wall orthophotograph by using a gray value p as an image gray value, wherein the coordinate of each pixel is (i, j), the pixel origin is positioned at the upper left corner of the image, and each pixel point comprises original point cloud coordinate information (c) (
）；
(3) Identifying pixel positions in the image map generated in step (2) of the left and right waist seams A, B in each ring one by one through an image identification means;
(4) automatically extracting points with the distance of 0.813m from the waist seam in the point cloud below each ring of waist seam as transverse diameter extraction reference points;
(5) calculating the distance between points of the automatically extracted reference points ring by ring to be used as the horizontal diameter of the current shield tunnel ring;
(6) automatically detecting the horizontal diameter quality extracted loop by loop, performing manual intervention aiming at the diameter with poor extraction quality, and correcting the position of a datum point.
The method for identifying the waist seam based on the tunnel inner wall image comprises the following steps:
(1) manually selecting the approximate range of a single-side waist seam in a first ring on the image of the inner wall of the tunnel;
(2) performing contrast adjustment on the image in the selected range by using a corrosion expansion algorithm;
(3) performing edge detection in the horizontal direction by using a Sobel operator, extracting an image edge, recording edge pixel coordinates as the current waist seam position, and calculating extraction precision;
(4) and (4) repeating the steps (2) and (3) to extract the coordinates of the girth seam-by-girth seam pixels, designing a state transition matrix, and performing prediction correction by using Kalman filtering to obtain the final girth seam position.
According to the identified positions of the waist seams at the two sides, the step of automatically extracting the diameter measurement datum points from the point cloud comprises the following steps:
(1) all the scanning lines of the current ring are selected from each ring m to form a scanning line set
；
(2) Go through
Selecting points from the position of the waist seam to the bottom of the tunnel from each scanning line n, and storing the points into a point set in sequence
；
(3) Go through
The distance from the point k to the position of the waist seam in the XOY plane is calculated
；；
(4) Calculating the distance of the points k in all the scanning lines n to form a distance set
；
(5) Computing
Median distance of (3)
Use of
The waist seam distance at the current m ring points k is stored into a distance set
；
(6) Go through
The distance value of (1) is calculated to be different from 0.813m
Selecting
Minimum size
Record the current k value as
；
(7) Taking the central mileage of the ring m as a starting point, dividing intoCalculating the position of each scanning line n in the increasing and decreasing directions of the inward stroke
Distance between the point of the waist and the waist seam
Up to
Recording the current scan line position as
Then the diameter reference point extracted from the current ring m is
；
(8) All diameter reference points are calculated on a loop-by-loop basis.
Performing secondary identification on all the diameters extracted automatically, and calculating the difference between the current ring diameter and the diameters of the front ring and the rear ring respectively according to the diameter of each ring, and recording the difference as
，
If, if
It means that there is a problem in automatically extracting the diameter of the current ring, and manual intervention is required to correct the diameter reference point.
The method has the advantages that: the diameter measurement benchmark close to the diameter measurement of the traditional total station is used instead of ellipse fitting, so that the point cloud diameter extraction effect is optimized. Compared with the common ellipse fitting extraction method in point cloud processing, the method provided by the invention improves the transverse diameter extraction precision, and is more beneficial to being fused with the traditional total station measurement result.
Drawings
FIG. 1 is a schematic diagram of data acquisition in the method of the present invention;
FIG. 2 is a schematic diagram of a reference point of a section diameter of a circular shield tunnel in the method of the present invention;
FIG. 3 is a schematic diagram of the extraction accuracy of the method of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings:
(1) the subway tunnel movement detection system shown in fig. 1 is used for carrying out movable three-dimensional laser data acquisition on a subway shield tunnel to obtain shield tunnel point cloud information, wherein the point cloud information comprises point cloud coordinates (X, Y, Z) and a gray value p, the Y axis points to the vertical direction, the X axis points to the horizontal direction, and the Z axis points to the mileage direction.
(2) Projecting the three-dimensional point cloud in the step (1) to a plane by using cylindrical tangent projection, generating a complete tunnel inner wall orthophoto map by using a gray value p as an image gray value, wherein the coordinate of each pixel is (i, j), the pixel origin is positioned at the upper left corner of the image, the horizontal direction is i, the vertical direction is j, each pixel point takes (i, j) as an index, and the pixel points all contain original point cloud coordinate information (c
）。
(3) As shown in fig. 2, the circular shield tunnel in this embodiment is formed by splicing a plurality of arc-shaped segments, the waist seam is a segment seam located at the left and right waist portions in the tunnel ring, the seam has a higher gray value in the image, and the pixel positions in the image generated in step (2) by the left and right waist seams A, B in each ring can be identified one by an image identification means, which specifically includes the following steps:
a) manually selecting the approximate range of a single-side waist seam in a first ring on the image of the inner wall of the tunnel as an initial value of the waist seam identification position;
b) performing contrast adjustment on the image in the selected range by using a corrosion expansion algorithm;
c) the Sobel operator is used for carrying out edge detection in the horizontal direction, the pixel gray scale of an edge part is set to be 255, the pixel gray scale of a non-edge part is set to be 0,counting the gray sum of all pixels in t rows in the selected range, and recording the sum into a collection
To, for
Sorting all the elements in the Chinese character 'Zhongji', and selecting t with the maximum value as the row number of the waist seam;
d) and (3) predicting the position of the waist seam of the next ring by using Kalman filtering according to the position of the waist seam identified by the previous ring, repeating the steps a) to c), and correcting the predicted value to be the final position of the waist seam.
(4) As shown in fig. 1, the diameter reference point A, B is a position below the waist seam and having a chord length from the waist seam of 0.813m, and the position is a diameter measurement reference point used in the measurement of the conventional total station, and a point in the point cloud below each ring of waist seams and having a chord length from the waist seam of 0.813m is automatically extracted as a transverse diameter extraction reference point, and the method specifically includes the following steps:
a) all the scanning lines of the current ring are selected from each ring m to form a scanning line set
；
b) Go through
Selecting the point from the position of the waist seam to the bottom of the tunnel to form a scanning line set
；
c) Go through
Calculating the distance from the point k to the position of the waist seam in the XOY plane
；
d) Calculating the mid-points of all the scanning lines nDistance of k
Form a distance set
；
e) Computing
Median distance of (3)
Use of
The waist seam distance at the current m ring points k is stored into a distance set
；
f) Go through
The distance value of (1) is calculated to be different from 0.813m
Selecting
Minimum size
Record the current k value as
；
g) Taking the mileage at the center of the circle m as a starting point, respectively calculating the position in each scanning line n in the increasing and decreasing directions of the mileage
Distance between the point of the waist and the waist seam
Up to
Recording the current scan line position as
Then the diameter reference point extracted from the current ring m is
Wherein the reference point corresponding to the waist seams A, B is
、
；
h) All diameter reference points are calculated on a loop-by-loop basis.
(5) According to
、
Obtaining the original point cloud coordinates of the two side reference points (
）、（
) Calculating the cross-sectional distance between two points
And obtaining the transverse diameter of the current ring i.
(6) Automatically detecting the horizontal diameter quality extracted loop by loop, performing manual intervention aiming at the diameter with poor extraction quality, and correcting the position of a datum point. The method comprises the following steps: the difference between the current ring diameter and the diameters of the front and rear rings is calculated separately and recorded as
，
If, if
And is
It means that there is a problem in automatically extracting the diameter of the current ring, and manual intervention is required to correct the diameter reference point.
This example, when embodied:
a circular shield tunnel section of a certain subway comprises 675 annular sheets, a total station and a mobile three-dimensional laser scanning system are respectively adopted to carry out data acquisition on the tunnel, and the transverse diameter of the annular sheets in the section is measured.
The total station adopts the traditional technical means to directly measure the diameter reference points on the two sides of the ring piece as shown in figure 2, and obtains the transverse diameter. The three-dimensional laser scanning data is processed by the following two means:
A. carrying out ellipse fitting on the cloud data of each ring point, and extracting the long axis of the ellipse as the transverse diameter;
B. the method is adopted for processing, the diameter reference point is automatically extracted, and the transverse diameter is calculated.
The method adopts a commonly used total station measurement result with higher precision as a reference, and the transverse diameters calculated by A, B two algorithms are respectively different from the total station result, and the comparison result is shown in fig. 3, wherein O data is the transverse diameter calculated by the method of the invention, and x data is the transverse diameter obtained by ellipse fitting extraction.
Claims (1)
1. An automatic extraction method for the transverse diameter of a subway circular shield tunnel is used for extracting the tunnel pipe diameter in tunnel point cloud obtained by a three-dimensional laser scanner, and is characterized by comprising the following steps:
(a) acquiring shield tunnel point cloud information by using a three-dimensional laser scanner, wherein the shield tunnel point cloud information comprises point cloud coordinates (X, Y, Z) and a gray value p, the Y axis points to the vertical direction, the X axis points to the horizontal direction, and the Z axis points to the mileage direction;
(b) projecting the three-dimensional point cloud in the step (a) to a plane by using cylindrical tangent projection, and generating a complete tunnel inner wall orthophotograph by using a gray value p as an image gray value, wherein the coordinate of each pixel is (i, j), the pixel origin is positioned at the upper left corner of the image, and each pixel point comprises original point cloud coordinate information (i, j) as an index
）；
(c) Through an image recognition means, pixel positions in the image map generated in the step (b) of the left and right waist seams A, B in each ring are recognized one by one, and the following steps (c1) - (c4) are adopted for a waist seam recognition algorithm of the left and right waist seams: (c1) manually selecting the approximate range of a single-side waist seam in a first ring on the image of the inner wall of the tunnel as an initial value of the waist seam identification position; (c2) performing contrast adjustment on the image in the selected range by using a corrosion expansion algorithm; (c3) using Sobel operator to carry out edge detection in horizontal direction, setting the gray level of the pixels at the edge part as 255 and the gray level of the pixels at the non-edge part as 0, counting the gray level sum of all the pixels at t rows in the selected range, and recording the sum into a collection set
To, for
Sorting all the elements in the Chinese character 'Zhongji', and selecting t with the maximum value as the row number of the waist seam; (c4) using Kalman filtering, predicting the position of the waist seam in the next ring from the position of the waist seam identified in the previous ring, and repeating the steps (c1) - (c3)Correcting the predicted value to be used as a final waist seam position;
(d) automatically extracting points with the distance of 0.813m from the waist seam in the point cloud below each ring waist seam to serve as transverse diameter extraction datum points, wherein the steps (d1) - (d8) for automatically extracting the datum points are as follows; (d1) all the scanning lines of the current ring are selected from each ring m to form a scanning line set
(ii) a (d2) Go through
Selecting the point from the position of the waist seam to the bottom of the tunnel to form a scanning line set
(ii) a (d3) Go through
Calculating the distance from the point k to the position of the waist seam in the XOY plane
(ii) a (d4) Calculating the distance of the points k in all the scanning lines n
Form a distance set
(ii) a (d5) Computing
Median distance of (3)
Use of
The waist seam distance at the current m ring points k is stored into a distance set
(ii) a (d6) Go through
The distance value of (1) is calculated to be different from 0.813m
Selecting
Minimum size
Record the current k value as
(ii) a (d7) Taking the mileage at the center of the circle m as a starting point, respectively calculating the position in each scanning line n in the increasing and decreasing directions of the mileage
Distance between the point of the waist and the waist seam
Up to
Recording the current scan line position as
Then the diameter reference point extracted from the current ring m is
(ii) a (d8) Calculating all diameter reference points ring by ring;
(e) calculating the distance between points of the automatically extracted reference points ring by ring to be used as the horizontal diameter of the current shield tunnel ring;
(f) automatically detecting the horizontal diameter quality extracted loop by loop, performing manual intervention aiming at the diameter with poor extraction quality, and correcting the position of a reference point
，
If, if
And is
It means that there is a problem in automatically extracting the diameter of the current ring, and manual intervention is required to correct the diameter reference point.
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| CN112036508B (en) * | 2020-09-27 | 2023-05-02 | 上海京海工程技术有限公司 | Automatic circumferential seam identification method based on shield tunnel lining structure |
| CN112985289A (en) * | 2021-04-28 | 2021-06-18 | 上海同禾工程科技股份有限公司 | Tunnel multi-section measurement monitoring system and monitoring method |
| CN114046747A (en) * | 2021-06-03 | 2022-02-15 | 北京工业大学 | Intelligent shield tunnel inter-ring dislocation analysis method based on moving point cloud data |
| CN114267039B (en) * | 2021-12-15 | 2024-06-11 | 上海勘察设计研究院(集团)股份有限公司 | Recognition result fine processing method based on shield tunnel transverse seam priori rules |
| CN114370828B (en) * | 2021-12-28 | 2023-06-20 | 中国铁路设计集团有限公司 | Shield tunnel diameter convergence and radial dislocation detection method based on laser scanning |
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| CN103090842B (en) * | 2013-02-07 | 2016-04-06 | 上海岩土工程勘察设计研究院有限公司 | The method of a kind of circular shield tunnel multi sphere section cross section correct |
| CN103913117B (en) * | 2014-03-26 | 2016-11-16 | 上海数联空间科技有限公司 | A kind of three-dimensional laser scanner positioner and laser point cloud absolute fix method |
| CN104266591A (en) * | 2014-09-29 | 2015-01-07 | 樊晓莉 | Displacement detection method for moving device in tunnel |
| CN104359459B (en) * | 2014-12-04 | 2017-02-22 | 上海岩土工程勘察设计研究院有限公司 | Method for scanning reflectivity information to generate tunnel lining image by virtue of three-dimensional laser |
| CN104680579B (en) * | 2015-03-02 | 2017-09-01 | 北京工业大学 | Tunnel construction informatization monitoring system based on three-dimensional scanning point cloud |
| CN205228438U (en) * | 2015-12-23 | 2016-05-11 | 上海申通地铁集团有限公司 | Tunnel convergence diameter measurement system |
| CN107180409B (en) * | 2017-03-31 | 2021-06-25 | 河海大学 | Generalized cylindrical projection method for three-dimensional point cloud of bent skeleton type object |
| CN107270825B (en) * | 2017-05-11 | 2019-08-23 | 上海勘察设计研究院(集团)有限公司 | A kind of great circle shield tunnel diameter calculation method |
| CN108362308B (en) * | 2018-01-19 | 2021-09-03 | 同济大学 | Mileage correction method for mobile laser measurement system by using tunnel circular seam |
| CN108230344B (en) * | 2018-01-24 | 2021-11-02 | 上海勘察设计研究院(集团)有限公司 | Automatic identification method for tunnel water leakage diseases |
| CN108917711B (en) * | 2018-06-07 | 2021-01-15 | 中铁三局集团有限公司 | Tunnel engineering three-dimensional laser scanning sectional measurement method and system |
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