Method for collecting images of a roadway wall

Abstract

Embodiments of the present application relate to the field of stereophotogrammetry, and particularly to a method for collecting images of a roadway wall. The method adjusts the image collection device to a predetermined height, so that the image collection device maintains the same distance from the bottom of the wall at each collection position, ensuring that all photos are consistent in initial imaging conditions, reducing the need for on-site test shooting, repeated adjustments and other steps, reducing experience dependence, and facilitating subsequent rapid completion of standardized collection. The spacing between adjacent collection positions is determined according to the parameters of the image collection device and the actual size of the roadway, and then the image collection device is moved and repeatedly photographed, so that the entire wall is equally spaced into multiple imaging units. The images of each imaging unit correspond to each other in space and can be spliced to generate a complete and continuous wall image. Moreover, the operator only needs to move the image collection device, which can be remotely controlled to shoot from a relatively safe position, reducing the risk of operation.

Description

Technical Field

[0001] The embodiments of this application relate to the field of stereophotometry, and in particular to a method for acquiring images of tunnel walls. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] During tunnel excavation, cracks will form on the tunnel walls. If the cracks are dense or large, they may loosen the rock mass and increase the risk of tunnel collapse. Therefore, geological information such as cracks in the tunnel walls can reflect the integrity of the surrounding rock, and obtaining this geological information helps in analyzing the stability of the surrounding rock. Summary of the Invention

[0004] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0005] An embodiment of this application provides a method for acquiring images of a tunnel wall, comprising the following steps: S10: deploying an image acquisition device at a predetermined acquisition position within the tunnel; S20: determining the acquisition spacing of the image acquisition device based on the parameters of the image acquisition device and the parameters of the tunnel; S30: adjusting the image acquisition device to a predetermined acquisition height; S40: taking a photograph of the tunnel wall at the predetermined acquisition position using the image acquisition device; S50: moving the image acquisition device at the acquisition spacing to the next acquisition position and taking a photograph of the tunnel wall at the next acquisition position; S60: repeating steps S40-S50 until the image acquisition of the entire tunnel wall is completed.

[0006] The method for acquiring images of tunnel walls provided in this application adjusts the image acquisition device to a predetermined height, ensuring that the device maintains the same distance from the bottom of the wall at each acquisition position. This guarantees that all photos are consistent in initial imaging conditions, reducing on-site trial shots and repeated adjustments, minimizing reliance on experience, and facilitating rapid standardized acquisition. The spacing between adjacent acquisition positions is determined based on the parameters of the image acquisition device and the actual dimensions of the tunnel. By successively moving the image acquisition device and repeatedly taking pictures, the entire wall can be divided into multiple equally spaced imaging units. The images of each imaging unit correspond spatially and can be stitched together to generate a complete and continuous wall image. Furthermore, operators only need to move the image acquisition device to remotely control the shooting from a relatively safe position, reducing operational risks. Attached Figure Description

[0007] To further illustrate the above and other advantages and features of this application, the specific embodiments of this application will be described in more detail below with reference to the accompanying drawings. The drawings, together with the following detailed description, are included in and form a part of this specification. Elements having the same function and structure are indicated by the same reference numerals. It should be understood that these drawings only depict typical examples of this application and should not be considered as limiting the scope of this application.

[0008] Figure 1 This is a schematic diagram illustrating the use of an image acquisition device to acquire images of the tunnel wall at multiple acquisition locations within the tunnel, as provided in the embodiments of this application. Figure 2 This is a schematic diagram illustrating the acquisition of an image of the tunnel wall at a single acquisition location within a tunnel using the method provided in the embodiments of this application. Figure 3 This is a schematic diagram of the image acquisition device used in the method provided in the embodiments of this application; Figure 4 This is a schematic diagram showing the distribution of multiple acquisition locations in the method provided in the embodiments of this application.

[0009] Explanation of reference numerals in the attached figures: 1. Support unit; 2. Height adjustment unit; 3. Lighting unit; 4. Angle adjustment unit; 5. Camera unit; 100. Image acquisition equipment; 10. Center line of the tunnel bottom. Detailed Implementation

[0010] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0011] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0012] The following disclosure provides several different implementations or examples for carrying out this application. To simplify the disclosure of this application, specific examples of components and methods are described below. Of course, these are merely examples and are not intended to limit this application. In the description of the embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0013] The tunnel cross-section formed by a hard rock tunnel boring machine (TBM) is circular. Currently, most tunnel geological information is acquired through manual on-site observation. This method is labor-intensive, inefficient, and difficult to match the rapid excavation pace of hard rock TBMs. Furthermore, the acquired geological information lacks standardization, making subsequent information processing and analysis challenging. Moreover, close-range manual work poses safety risks when there are localized safety hazards such as rockfalls, spalling, or limited working space. Therefore, image acquisition methods offer a new methodological reference for solving these problems. However, existing image acquisition methods often rely on manual handheld cameras to capture images segment by segment, making it difficult to consistently control the consistency of the acquired images, which affects the quality of subsequent 3D tunnel model construction and geological information interpretation.

[0014] To address the aforementioned problems, embodiments of this application provide a method for acquiring images of tunnel walls, comprising the following steps: S10: deploying an image acquisition device at a predetermined acquisition position within the tunnel; S20: determining the acquisition spacing of the image acquisition device based on the parameters of the image acquisition device and the parameters of the tunnel; S30: adjusting the image acquisition device to a predetermined acquisition height; S40: taking a photograph of the tunnel wall at the predetermined acquisition position using the image acquisition device; S50: moving the image acquisition device along the acquisition spacing to the next acquisition position and taking a photograph of the tunnel wall at the next acquisition position; S60: repeating steps S40-S50 until the image acquisition of the entire tunnel wall is completed.

[0015] The method for acquiring images of tunnel walls provided in this application adjusts the image acquisition device to a predetermined height, ensuring that the device maintains the same distance from the bottom of the wall at each acquisition position. This guarantees that all photos are consistent in initial imaging conditions, reducing on-site trial shots and repeated adjustments, minimizing reliance on experience, and facilitating rapid standardized acquisition. The spacing between adjacent acquisition positions is determined based on the parameters of the image acquisition device and the actual dimensions of the tunnel. By successively moving the image acquisition device and repeatedly taking pictures, the entire wall can be divided into multiple equally spaced imaging units. The images of each imaging unit correspond spatially and can be stitched together to generate a complete and continuous wall image. Furthermore, operators only need to move the image acquisition device to remotely control the shooting from a relatively safe position, reducing operational risks.

[0016] In some embodiments, step S20 specifically includes the following steps: S21: determining the field of view of the image acquisition device in the axial direction of the roadway; S22: determining the radius of the roadway; S23: determining the acquisition spacing of the image acquisition device based on the field of view of the image acquisition device in the axial direction of the roadway and the radius of the roadway.

[0017] By determining the axial field of view of the image acquisition equipment and the tunnel radius, the axial width and actual arc length of the tunnel wall that can be covered by a single shot can be limited. The acquisition interval determined in this way can ensure a stable overlap between adjacent photos in the axial direction, avoiding missed shots and reducing overlap redundancy. Subsequent shots taken at this acquisition interval can ensure that images of the entire tunnel wall are continuously and completely acquired.

[0018] In some embodiments, step S23 specifically includes the following steps: S231: Determine the coverage length of a single photograph in the axial direction of the tunnel based on the field of view of the image acquisition device in the axial direction of the tunnel and the radius of the tunnel; S232: Determine the overlap rate of adjacent photographs in the axial direction of the tunnel; S233: Determine the acquisition spacing based on the coverage length and the overlap rate of adjacent photographs in the axial direction of the tunnel. This setup allows any operator to determine the axial layout distance between adjacent acquisition positions simply by determining parameters such as the tunnel radius, the lens parameters of the image acquisition device, and the target overlap rate of the photographs, thereby improving on-site acquisition efficiency.

[0019] Figure 1 This is a schematic diagram illustrating the method provided in the embodiments of this application, which uses an image acquisition device to acquire images of the tunnel wall at multiple acquisition locations within the tunnel. In some embodiments, in step S231, as shown... Figure 1 As shown, the coverage length of a single photograph in the axial direction of the alley is determined as follows: Where B represents the coverage length of a single image in the axial direction of the tunnel; r represents the radius of the tunnel; β represents the field of view of the image acquisition device in the axial direction of the tunnel; D represents the tunnel excavation direction; S represents the acquisition spacing; and P represents the midpoint of the tunnel bottom. The acquisition spacing determined in this way can strictly correspond to the actual tunnel size, avoiding insufficient overlap or excessive redundancy caused by inaccurate estimation of coverage length.

[0020] In some embodiments, in step S233, the acquisition interval is determined as follows: Where B represents the coverage length of a single image in the axial direction of the alleyway; S represents the acquisition interval. This indicates the overlap rate of adjacent photos along the axial direction of the tunnel. By determining the acquisition interval based on the difference between the axial coverage length of a single photo and the axial length corresponding to the overlapping portion, it avoids generating a large number of duplicate images due to excessively short movements, and also avoids losing the common features required for photo stitching due to excessively long movements. This effectively controls the acquisition workload while ensuring complete image stitching.

[0021] In some embodiments, step S40 specifically includes the following steps: S41: determining the circumferential field of view of the image acquisition device in the tunnel; S42: determining the overlap rate of adjacent photos in the circumferential direction of the tunnel; S43: determining the number of photos taken by the image acquisition device at a single acquisition position based on the circumferential field of view of the image acquisition device in the tunnel and the overlap rate of adjacent photos in the circumferential direction of the tunnel; S44: causing the image acquisition device to take the number of photos determined in step S43 at a predetermined acquisition position against the tunnel wall.

[0022] The field of view of the image acquisition equipment in the circumferential direction of the tunnel reflects the circumferential range that a single photo can cover on the curved surface of the tunnel wall. The set overlap rate between adjacent photos can control the degree of overlap of photos in the circumferential direction, thereby determining the number of photos that need to be taken at a single acquisition position. This ensures that the circumferential coverage of the photos is continuous and that the required overlap is maintained between adjacent photos, so that the entire circumferential surface of the tunnel wall corresponding to each acquisition position is completely recorded without any omissions or repetitions in the circumferential direction.

[0023] In some embodiments, step S43 specifically includes the following steps: S431: Determine the shooting angle interval of adjacent photos in the circumferential direction of the image acquisition device in the tunnel based on the circumferential field of view of the image acquisition device in the tunnel and the overlap rate of adjacent photos in the circumferential direction of the tunnel; S432: Determine the number of photos taken by the image acquisition device at a single acquisition position based on the shooting angle interval and the overlap rate of adjacent photos in the circumferential direction of the tunnel, so that the photos obtained at the same acquisition position are evenly distributed in the circumferential direction and meet the overlap rate requirements.

[0024] Figure 2 This is a schematic diagram illustrating the acquisition of images of the tunnel wall at a single acquisition location within a tunnel using the method provided in the embodiments of this application. In some embodiments, such as... Figure 2 As shown, in step S431, the shooting angle interval is determined as follows: ;in, α represents the shooting angle interval; α represents the circumferential field of view of the image acquisition equipment in the alleyway. This represents the overlap rate of adjacent photos in the circumferential direction of the tunnel. O represents the shooting center of the image acquisition device, P represents the midpoint of the tunnel bottom, and A represents the overlap range of adjacent photos in the circumferential direction at that acquisition location. This setting ensures that all photos at the same acquisition location are evenly distributed in the circumferential direction, avoiding gaps between adjacent photos due to excessive rotation angles and excessive overlap due to insufficient rotation angles, thus improving the acquisition efficiency of a single acquisition location.

[0025] In some embodiments, in step S432, the number of photos taken by the image acquisition device at a single acquisition location is determined in the following manner: ;in, Ω represents the shooting angle interval; Ω represents the actual circumferential shooting angle range of the image acquisition device at a single acquisition position; N represents the number of photos taken by the image acquisition device at a single acquisition position. This symbol represents rounding up. Rounding up can compensate for situations where the actual angle range may not be divisible by the angle interval, avoiding gaps in the final coverage due to insufficient rounding. Furthermore, by adding 1, a closed overlap is formed between the first and last photos, ensuring that the circumferential tunnel wall image is completely acquired.

[0026] In some embodiments, when a single acquisition position needs to cover the entire circumference of the tunnel wall, Ω is 360°; when it only needs to cover the effective tunnel wall range from the bottom of one side of the tunnel wall to the bottom of the other side of the tunnel wall, Ω is the corresponding effective shooting angle range.

[0027] In some embodiments, such as Figure 2 As shown, in step S30, the predetermined acquisition height is the height of the center of the cross-section of the tunnel, i.e. Figure 2 The location of midpoint O ensures that the lens optical axis is perpendicular to the surface of the tunnel wall, guaranteeing consistent shooting. Furthermore, it ensures that the same center point is used as a reference when determining the shooting distance, circumferential shooting angle interval, and number of photos taken at multiple shooting locations. This allows the image acquisition equipment to maintain a consistent imaging geometry during movement and rotation, ensuring that each photo has a consistent projection reference in space. This provides accurate coordinate correspondence for stitching adjacent photos, resulting in natural stitching along both the circumferential and axial directions during the final stitching process.

[0028] Figure 3 This is a schematic diagram of the structure of the image acquisition device used in the method provided in the embodiments of this application, as shown below. Figure 3As shown, the image acquisition device 100 includes a support unit 1, a height adjustment unit 2, an illumination unit 3, an angle adjustment unit 4, and an imaging unit 5. The height adjustment unit 2 connects the support unit 1 and the illumination unit 3. The angle adjustment unit 4 and the imaging unit 5 are sequentially arranged on the illumination unit 3. The height adjustment unit 2 can extend and retract to adjust the height of the imaging unit 5, and the angle adjustment unit 4 can rotate to adjust the angle of the imaging unit 5. The above structure is easy to assemble and maintain, and can be applied to tunnels of different sizes.

[0029] In some embodiments, the lighting unit 3 can be a ring-shaped light array, which is arranged to surround the periphery of the shooting unit 5 and is fixed separately from it. During the shooting process, the ring-shaped light array remains fixed and continuously provides supplementary lighting for the tunnel wall. The separate fixing can reduce the load on the angle adjustment unit 4 and improve the stability of the shooting unit 5. Preferably, the lamps in the ring-shaped light array should be detachable and rechargeable.

[0030] In some embodiments, the image acquisition device 100 may further include a control unit, which is used to remotely control the rotation of the shooting unit 5 and the angle adjustment unit 4, and to transmit the acquired images to a terminal device (which may use a wireless connection method such as a wireless local area network or Bluetooth). Operators only need to move the image acquisition device to remotely control the shooting from a relatively safe position, reducing the risk of prolonged close contact with unstable cave walls.

[0031] In some embodiments, the imaging unit 5 includes a single camera and a fixed-focus lens to fix the field of view for a single shot, facilitating standardized calculation of the circumferential shooting angle interval and axial acquisition spacing, while ensuring imaging stability. The camera may be an SLR camera or other high-resolution camera.

[0032] In some embodiments, the height adjustment unit 2 is preferably a telescopic rod with length markings and includes a locking mechanism and a limiting mechanism to stabilize the position of the shooting unit 5.

[0033] In some embodiments, the support unit 1 is preferably an adjustable tripod, which may be equipped with a leveling bubble or electronic level for quick leveling to adapt to local undulations in the road surface; preferably, the length of each leg of the tripod is adjustable to adapt to the curved bottom of the roadway and local conditions of gravel and debris.

[0034] In step S30, the target elongation L of the height adjustment unit 2 can be determined as follows: r represents the radius of the tunnel. This indicates the distance between the lower end of the height adjustment unit 2 and the midpoint of the bottom of the tunnel. This indicates the distance between the upper end of the height adjustment unit 2 and the center point of the imaging unit 5. By fixing the length of the height adjustment unit 2 to L, the height of the center point of the imaging unit 5 can be kept on the axis of the tunnel. There is no need to reposition the center height of the imaging unit 5 at each acquisition position, which improves acquisition efficiency and makes it easy to adapt to tunnels of different sizes.

[0035] Figure 4 This is a schematic diagram showing the distribution of multiple acquisition locations in the method provided by the embodiments of this application. In some embodiments, such as... Figure 1 , Figure 3 and Figure 4 As shown, each acquisition position, i.e. the setting position of support unit 1, should be distributed at the center line 10 at the bottom of the tunnel. This makes the circumferential field of view of the lens and the circumferential coverage angle directly correspond, so that the shooting angle interval can be directly determined by the circumferential field of view and the overlap rate of adjacent photos in the circumferential direction of the tunnel.

[0036] In some embodiments, the scope of image acquisition can be the tunnel section that has been excavated after a tunnel boring machine completes one round of excavation, and must meet the conditions for safe operation.

[0037] In some embodiments, the overlap rate of adjacent photographs in the circumferential direction of the tunnel is preferably greater than 60%.

[0038] In some embodiments, the overlap rate of adjacent photographs in the axial direction of the tunnel is preferably greater than 60%.

[0039] In some embodiments, the angle adjustment unit 4 controls the shooting unit 5 to rotate and shoot one image at a time, starting from the bottom of one side of the tunnel wall and ending at the bottom of the other side of the tunnel wall; or to complete continuous circumferential shooting at a preset effective angle.

[0040] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0041] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A method for acquiring images of tunnel walls, characterized in that, It includes the following steps: S10: Deploy the image acquisition device at the predetermined acquisition location within the alleyway; S20: Determine the acquisition spacing of the image acquisition device based on the parameters of the image acquisition device and the parameters of the roadway; S30: Adjust the image acquisition device to the predetermined acquisition height; S40: The image acquisition device takes a picture of the cave wall at the predetermined acquisition position; S50: Move the image acquisition device by the acquisition interval to the next acquisition position and take a picture of the cave wall at the next acquisition position; S60: Repeat steps S40-S50 until the image acquisition of the entire tunnel wall is completed.

2. The method according to claim 1, characterized in that, Step S20 specifically includes the following steps: S21: Determine the field of view angle of the image acquisition device in the axial direction of the roadway; S22: Determine the radius of the tunnel; S23: Determine the acquisition spacing of the image acquisition device based on the field of view of the image acquisition device in the axial direction of the roadway and the radius of the roadway.

3. The method according to claim 2, characterized in that, Step S23 specifically includes the following steps: S231: Based on the field of view of the image acquisition device in the axial direction of the alley and the radius of the alley, determine the coverage length of a single photograph in the axial direction of the alley; S232: Determine the overlap rate of adjacent photographs in the axial direction of the tunnel; S233: Determine the acquisition spacing based on the coverage length and the overlap rate of adjacent photographs in the axial direction of the alley.

4. The method according to claim 3, characterized in that, In step S231, the coverage length of a single photograph in the axial direction of the tunnel is determined as follows: ； Wherein, B represents the coverage length of a single photograph in the axial direction of the alley; r represents the radius of the alley; and β represents the field of view angle of the image acquisition device in the axial direction of the alley.

5. The method according to claim 3, characterized in that, In step S233, the acquisition interval is determined as follows: ； Where B represents the coverage length of a single photograph in the axial direction of the alleyway; S represents the acquisition interval; This indicates the overlap rate of adjacent photographs in the axial direction of the tunnel.

6. The method according to claim 1, characterized in that, Step S40 specifically includes the following steps: S41: Determine the field of view angle of the image acquisition device in the circumferential direction of the alleyway; S42: Determine the overlap rate of adjacent photographs in the circumferential direction of the tunnel; S43: Determine the number of photos taken by the image acquisition device at a single acquisition position based on the circumferential field of view of the image acquisition device in the tunnel and the overlap rate of adjacent photos in the circumferential direction of the tunnel. S44: The image acquisition device takes the number of photos determined in step S43 at the predetermined acquisition position of the cave wall.

7. The method according to claim 6, characterized in that, Step S43 specifically includes the following steps: S431: Determine the shooting angle interval of adjacent photos in the circumferential direction of the tunnel based on the field of view of the image acquisition device in the circumferential direction of the tunnel and the overlap rate of adjacent photos in the circumferential direction of the tunnel. S432: Determine the number of photos taken by the image acquisition device at a single acquisition position based on the shooting angle interval and the overlap rate of adjacent photos in the circumferential direction of the alley.

8. The method according to claim 7, characterized in that, In step S431, the shooting angle interval is determined as follows: ； in, The shooting angle interval is indicated by α; α represents the circumferential field of view of the image acquisition device in the alleyway. This indicates the overlap rate of adjacent photographs in the circumferential direction of the tunnel.

9. The method according to claim 7, characterized in that, In step S432, the number of photos taken by the image acquisition device at a single acquisition location is determined as follows: ; in, Ω represents the shooting angle interval; Ω represents the actual circumferential shooting angle range of the image acquisition device at a single acquisition position; N represents the number of photos taken by the image acquisition device at a single acquisition position; The symbol indicates rounding up.

10. The method according to any one of claims 1-9, characterized in that, In step S30, the predetermined acquisition height is the height of the center of the cross-section of the tunnel.

Images