阅读说明：本技术 一种基于球型摄像机拍摄隧道墙面裂缝的装置与方法 (Device and method for shooting cracks on tunnel wall surface based on dome camera ) 是由 丁宥安 孙晨 崔何亮 于 2021-05-28 设计创作，主要内容包括：本发明涉及一种基于球型摄像机拍摄隧道墙面裂缝的装置与方法,包括球型摄像机与平面镜装置,通过数学计算,得到镜面与摄像机的旋转角度；平面镜安装在裂缝区域附近,调整平面镜角度后,待球型摄像机视线与裂缝虚像平面垂直,拍摄镜面中的裂缝成像,在拍摄过程中调整相机焦距,尽可能覆盖隧道墙面上裂缝信息,获取裂缝图片；利用平面镜装置的球型摄像机拍摄方法,可以避开大量无关背景对隧道墙面裂缝成像的干扰,大大提高隧道墙面裂缝图片的清晰度。同时,在保证每次拍摄时所获取的照片呈正视图的前提下,本发明可以极大的减少后期隧道墙面裂缝分析相关工作的繁杂性,并且提高隧道墙面裂缝数据分析的精确性。(The invention relates to a device and a method for shooting a tunnel wall crack based on a spherical camera, wherein the device comprises the spherical camera and a plane mirror device, and the rotation angle between a mirror surface and the camera is obtained through mathematical calculation; the plane mirror is arranged near the crack area, after the angle of the plane mirror is adjusted, when the sight line of the spherical camera is perpendicular to the crack virtual image plane, the crack in the mirror surface is shot for imaging, the focal length of the camera is adjusted in the shooting process, the crack information on the tunnel wall surface is covered as much as possible, and a crack picture is obtained; by using the shooting method of the spherical camera of the plane mirror device, the interference of a large number of irrelevant backgrounds to the tunnel wall crack imaging can be avoided, and the definition of the tunnel wall crack image is greatly improved. Meanwhile, on the premise of ensuring that the picture acquired in each shooting is in a front view, the method can greatly reduce the complexity of related work of later tunnel wall crack analysis and improve the accuracy of tunnel wall crack data analysis.)

1. A device and a method for shooting cracks on a tunnel wall surface based on a dome camera are characterized in that: the device includes crack sign (1), runing rest (2), level crossing (3) and spherical camera (4) totally four parts, its characterized in that:

the crack mark (1) is composed of square iron sheets, the side length x of the square iron sheets is known, and the square iron sheets are symmetrically stuck to two sides of a crack;

the rotating bracket (2) is arranged on the inner wall of the tunnel where the crack is located through welding and keeps a proper distance from the crack;

the plane mirror (3) is arranged on the rotating bracket (2) in an embedded mode, and the imaging mirror faces towards the crack;

the spherical camera (4) is arranged on the wall of the inner wall of the tunnel, can rotate within 360 degrees in the plane and can capture crack images on the wall of the inner wall of the tunnel around.

2. The device and the method for shooting the cracks on the wall surface of the tunnel based on the dome camera according to the claim 1 are characterized in that: knowing that the actual side length of the crack identifier (1) is x, the number of pixels corresponding to the actual side length of the crack identifier (1) in a crack picture is n, and the actual side length of one pixel in the crack picture is y = x/n, the pixel calibration of the crack picture can be given, and a basis is provided for the subsequent calculation of the crack width w and the length l.

3. The device and the method for shooting the cracks on the wall surface of the tunnel based on the dome camera according to the claim 1 are characterized in that: utilize level crossing imaging principle in the physics, at crack vicinity installation runing rest (2) and level crossing (3), through the contained angle of runing rest (2) adjustable level crossing (3) and tunnel inner wall, can obtain the crack virtual image according to level crossing (3) imaging principle.

4. The device and the method for shooting the cracks on the wall surface of the tunnel based on the dome camera according to the claim 1 are characterized in that: after the plane mirror (3) and the rotating support (2) are installed, the shooting angle theta of the camera is adjusted through the installation angle alpha of the plane mirror (3), when the shooting sight line of the spherical camera is perpendicular to the crack virtual image, the front-view picture of the crack can be obtained through the imaging principle of the plane mirror (3) and the relation of similar triangles, and in the shooting process, the focal length of the camera is adjusted according to the image imaging effect of the picture, so that the picture with high quality is obtained.

5. The method for obtaining a fracture orthographic picture according to claim 4, wherein: the crack front view camera based on the spherical camera has the advantages that a scientific principle that a virtual image which is the same as a real object is formed due to reflection of light after the light enters the plane mirror is adopted, so that the shooting angle theta of the spherical camera (4) is adjusted through reflection of the light under the condition that a crack front view cannot be directly shot on site, the crack virtual image in the mirror surface is directly shot, and the front view of the crack is obtained.

6. A method for adjusting the angle of a dome camera (4) in obtaining a fracture orthographic picture according to claim 5, wherein: by utilizing a mathematical calculation formula, knowing a horizontal distance a between a crack and a dome camera (4), a distance h between the dome camera and a wall body and a distance b between the crack and a rotating support (2), solving to obtain a distance c between the rotating support (2) and an intersection point of a sight line of the dome camera (4) and a tunnel inner wall by establishing a tangent value of an included angle theta between the dome camera (4) and the tunnel inner wall, then obtaining theta through values of b and c and an arcsine formula, obtaining alpha according to an angle relation, and installing a plane mirror (3) according to alpha and theta.

7. The device and the method for shooting the cracks on the wall surface of the tunnel based on the dome camera according to any one of claims 1 to 4, wherein: the method comprises the following steps:

step 1: as shown in fig. 1, for obtaining actual data of the crack in the later analysis, crack markers (1) are symmetrically pasted on two sides of the crack as a scale converted by pixels: assuming that the actual side length of the known crack identifier (1) is x, the number of pixels corresponding to the crack identifier in the picture is n, and then the actual side length y = x/n corresponding to one pixel, and then the reference value calibrated by the pixels is y;

step 2: the installation angle of the plane mirror (3) and the shooting angle of the spherical camera (4) are obtained through mathematical calculation, and the mirror surface installation and the camera adjustment work are carried out by utilizing the rotating bracket (2); as shown in fig. 2, the calculation steps are as follows:

knowing the horizontal distance a between the crack and the dome camera (4), the distance h between the dome camera (4) and the inner wall of the tunnel and the distance b between the crack and the rotating support (2), the installation angle of the plane mirror (3) and the shooting angle of the dome camera (4) are obtained through the following mathematical calculation, so that an orthographic picture of the crack is obtained:

according toTo obtain the equation:，

and (4) solving the equation, wherein c can be solved:，

and because:，

therefore, the shooting angle of the dome camera (4) can be obtained，

According to the angle relation, the installation angle of the plane mirror (3) can be obtained，

The installation angle of the plane mirror (3) is obtained by the mathematical calculationShooting angle with the dome camera (4)The field installation is convenient;

and step 3: after the installation and adjustment work is finished, adjusting the shooting focal length of the camera, covering the information about the cracks on the wall surface as much as possible, and then shooting the imaging plane of the plane mirror (3) to obtain the picture of the cracks in the mirror surface;

and 4, step 4: analyzing the number n1 of pixels in the width direction of the crack in the picture by using an image processing technology, and deducing the width w = n1 x y of the crack according to the actual length y corresponding to each pixel calibrated by the pixels made by the crack identifier (1);

and 5: the number n2 of pixels in the crack length direction in the picture is analyzed by using an image processing technology, and the crack length l = n2 x y can be deduced according to the actual length y corresponding to each pixel of the pixel calibration made by the crack identifier (1).

Technical Field

The invention relates to a device and a method for shooting a tunnel wall crack based on a dome camera, belonging to the field of civil engineering structure health monitoring, in particular to the technical field of crack monitoring.

Background

Cracks are the most common defects with complex causes in civil engineering, the occurrence of cracks can affect the safety and the use of buildings, and the cracks can be continuously enlarged and degraded along with the invasion of external harmful components, so that engineering accidents are possibly caused. At present, because the service life of the existing tunnels in China is long, the harmful accidents caused by the problems of aging deformation, crack leakage and the like of all parts are rare, and therefore, the monitoring of the tunnels is very necessary.

At present, the cracks in the tunnel are mostly analyzed and monitored by computer vision, namely, marks are installed beside the cracks, a dome camera shoots pictures, and the real-time monitoring of the cracks is realized by a mode of transmitting the pictures to a computer through a cloud for image processing and analysis. This approach has high requirements on the quality of the acquired picture and the imaging angle. In practical engineering, under the condition that a spherical camera takes cracks as a main background in shooting, the problem of blurring of the obtained pictures mostly occurs, so that the precision of the pictures is not high, and the development of subsequent analysis work is not facilitated; meanwhile, the plane where the crack is located is not perpendicular to the sight line of the camera, so that the obtained picture can show an oblique shooting angle, and the data error of the crack obtained in the later image analysis is larger.

Therefore, in order to realize high-quality shooting of cracks occurring in complex projects such as tunnels while ensuring low risk and high safety, a device and a method for shooting cracks by using a spherical camera are required.

Disclosure of Invention

In order to solve the technical problems, the invention provides a device and a method for shooting a crack on a tunnel wall surface based on a dome camera.

The device for shooting the cracks in the tunnel by the aid of the dome camera comprises a plane mirror and a rotating support, and in order to guarantee safety of the mirror face, the safety distance between the mirror face and the wall is paid attention to during design. By utilizing the plane mirror imaging principle in physics, in the using process, the mirror surface can be subjected to angle adjustment according to the requirements of actual engineering by rotating the support, so that the cracks are imaged on the mirror surface, and the front view of the cracks can be shot by a spherical camera; besides the function of reflection imaging, the mirror surface can improve the imaging quality, and when the camera directly shoots the mirror surface, the influence of large-area irrelevant background is avoided.

A method for shooting a tunnel wall crack based on a spherical camera comprises the spherical camera and a related auxiliary device, namely, in a shooting preparation period, a mirror surface rotation angle is obtained through mathematical calculation under the condition that a crack virtual image is perpendicular to the sight of the camera, and a plane mirror is accurately installed near a crack area; and imaging the crack on the mirror surface to ensure that the sight line of the camera is vertical to the virtual image of the crack, and then shooting the crack.

The invention has the beneficial effects that:

the invention provides a device and a method for shooting a crack on a tunnel wall surface based on a dome camera, which can be used for monitoring the development condition of the crack of a building. This method has the following advantages: according to the method, the mode that the plane mirror is arranged near the crack area is utilized, so that the crack can be imaged on the mirror surface, the spherical camera can capture the front view of the crack, the complexity of later image analysis work is greatly reduced, and the accuracy of real-time crack data is improved.

The method is convenient to realize and low in cost, and can be realized only by installing the plane mirror on the plane where the crack is located; when the front view is guaranteed to be grabbed, due to the limitation of the mirror frame, the influence of a large number of irrelevant backgrounds on the image quality is avoided, the core area near the crack can be accurately extracted, and the method has great significance for the development of follow-up work. The method is widely applied, and not only is suitable for professional shooting for acquiring cracks on the tunnel, but also is suitable for detailed shooting for objects on various vertical surfaces.

Drawings

FIG. 1 is a photographic crack plan view of the device of the present invention;

FIG. 2 is a schematic view of the installation position of the apparatus of the present invention;

in the figure: 1-mark, 2-rotating bracket, 3-plane mirror and 4-spherical camera.

Detailed Description

The present invention is further illustrated by the following figures and specific examples, which are to be understood as illustrative only and not as limiting the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalent modifications thereof which may occur to those skilled in the art upon reading the present specification.

A device and a method for shooting cracks on a tunnel wall surface based on a dome camera comprise crack identifiers (1), a rotating support (2), a plane mirror (3) and the dome camera (4), and the specific operation steps are as follows:

step 1: as shown in fig. 1, for obtaining actual data of the crack in the later analysis, crack markers (1) are symmetrically pasted on two sides of the crack as a scale converted by pixels: knowing that the actual side length of the crack identifier (1) is x, the number of pixels corresponding to the crack identifier in the picture is n, and then the actual side length y = x/n corresponding to one pixel, and then the reference value calibrated by the pixel is y;

step 2: the installation angle of the plane mirror (3) and the shooting angle of the spherical camera (4) are obtained through mathematical calculation, and the mirror surface installation and the camera adjustment work are carried out by utilizing the rotating bracket (2); as shown in fig. 2, the calculation steps are as follows:

knowing the horizontal distance a between the crack and the dome camera (4), the distance h between the dome camera (4) and the inner wall of the tunnel and the distance b between the crack and the rotating support (2), and obtaining the installation angle of the plane mirror (2) and the shooting angle of the dome camera (4) through the following mathematical calculation so as to obtain an orthographic picture of the crack:

according toTo obtain the equation:，

and (4) solving the equation, wherein c can be solved:，

and because:，

therefore, the shooting angle of the dome camera (4) can be obtained，

According to the angle relation, the installation angle of the plane mirror (3) can be obtained，

The installation angle of the plane mirror (3) is obtained by the mathematical calculationShooting angle with the dome camera (4)The field installation is convenient;

and step 3: after the installation and adjustment work is finished, adjusting the shooting focal length of the camera, covering the information about the cracks on the wall surface as much as possible, and then shooting the imaging plane of the plane mirror (3) to obtain the picture of the cracks in the mirror surface;

and 4, step 4: analyzing the number n1 of pixels in the width direction of the crack in the picture by using an image processing technology, and deducing the width w = n1 x y of the crack according to the actual length y corresponding to each pixel calibrated by the pixels made by the crack identifier (1);

and 5: the number n2 of pixels in the crack length direction in the picture is analyzed by using an image processing technology, and the crack length l = n2 x y can be deduced according to the actual length y corresponding to each pixel of the pixel calibration made by the crack identifier (1).

According to the invention, a plane mirror is arranged near a crack area through a plane mirror imaging principle in physics, and the front view of the crack of the tunnel wall surface is shot by a spherical camera by utilizing the reflection of the crack on the mirror surface, so that a proper shot picture is obtained; through the imaging of the plane mirror, the influence of an irrelevant background on later-stage identification is avoided, and a high-quality shot picture is obtained; the shooting method and the auxiliary device are not only suitable for professional shooting for acquiring cracks in the tunnel by professionals, but also suitable for entertainment shooting in daily life and carrying out detailed shooting on objects on various vertical surfaces.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.