Laboratory scoured terrain acquisition method, medium and terminal

Abstract

The invention is suitable for the technical field of topographic survey, and relates to a laboratory scoured topography acquisition method, a medium and a terminal, and the method comprises the steps: obtaining a high-definition two-dimensional picture of a scoured topography; three-dimensional reconstruction and image tracking are carried out based on an AliceVision photogrammetry computer vision framework through Meshroom software, and terrain reconstruction is carried out based on SFM and MVS methods; the reconstructed terrain is stored as a file in an obj format, and the reconstructed terrain is processed through Meslab software; and after the processed file is exported as a three-dimensional cloud picture file in a Polygon File Format format, generating a terrain contour line through a mapping code or mapping software. The method is short in terrain reconstruction time consumption, high in operability, high in terrain reconstruction efficiency and high in accuracy of the obtained scoured terrain, and high-precision terrain scanning can be achieved under the condition that no terrain scanning equipment exists.

Description

Technical Field

[0001] The invention belongs to the technical field of topographic measurement, and in particular relates to a method, medium and terminal for obtaining laboratory scour topography. Background Art

[0002] Scour problems are common in river bridge projects, water conservancy projects and marine projects. When there are structures in the water flow environment, scour pits are formed under the combined effects of horseshoe vortices, streamline contraction and wake vortex shedding. Scours cause the foundation to be buried less deeply, seriously reduce the bearing capacity of the foundation, increase the risk of overturning of the structure, and have serious harm to the in-situ stability of the structure. At present, the research methods for scour problems are mainly divided into physical model experiments and numerical simulation calculations. Since scour problems involve three-phase flow of fluid, sediment and structure, the module of terrain change is added on the basis of traditional CFD simulation of fluid-solid coupling. The required computing resources are huge, time-consuming, and the overall research efficiency is low. Therefore, indoor physical model experiments are widely used in the study of scour problems and are the most common research method in scour research. The acquisition of scour terrain is the top priority of flume scour experiments, and the accuracy of the terrain obtained directly affects the experimental results.

[0003] Currently, the common scour terrain acquisition equipment used in water tanks is mainly underwater three-dimensional sonar scanners, underwater laser scanners, dot matrix scanners, etc., but the scanning equipment is expensive and the post-processing of the scanned terrain is relatively complicated; in addition, if the scour terrain is acquired without terrain scanning equipment, the existing method mainly uses oblique photogrammetry technology, using software to process two-dimensional terrain images and perform three-dimensional reconstruction, but key points need to be calibrated during reconstruction, which is time-consuming in the later reconstruction process. This method requires a large amount of work and has a low terrain reconstruction efficiency. In addition, this method can only obtain terrain changes within a small range, and cannot obtain scour terrain in a large range. The accuracy of the acquired scour terrain is also low. The patent with the announcement number CN113376639B provides a three-dimensional reconstruction method of the terrain of the scour area of ​​the bridge pier foundation based on scanning sonar imaging, which includes the following steps: step S1, using sonar to completely scan and image the terrain of the scour area of ​​the bridge pier foundation from different directions, and collect n groups of sound and image images of the foundation scour terrain; step S2, intercepting multiple analysis sections of the collected sound and image at the same interval; step S3, extracting the key parameters of the upper and lower edges of the image strip formed in the analysis section of the figure, converting them into three-dimensional space, and expressing the sonar beam fan with fan arcs; step S4, according to the relative position relationship of a group of measuring point fan arcs in the same analysis section, identifying the contour morphology of the scour terrain; step S5, identifying the contour morphology of each terrain one by one, and extracting the three-dimensional coordinate data of the spatial scattered points respectively; step S6, using the Kriging interpolation method to interpolate and fit the spatial scattered point data to complete the three-dimensional reconstruction of the foundation scour terrain. This method in this patent is used for actual river terrain scanning. The laboratory uses this method with high cost, complex process and low usability.

[0004] Therefore, how to provide a laboratory scour topography acquisition method with simple operation, high terrain reconstruction efficiency and high accuracy of acquired scour topography is an urgent problem to be solved by personnel in this technical field. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a laboratory scour topography acquisition method to solve the problems in the prior art that the laboratory scour topography acquisition method is relatively complicated to operate, and the terrain reconstruction efficiency and the accuracy of the acquired scour topography are low; in addition, the present invention also provides a laboratory scour topography acquisition medium and terminal.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for obtaining a laboratory scour topography, comprising the following steps:

[0008] S10, obtaining high-definition two-dimensional photos of the scour terrain; S20, performing three-dimensional reconstruction and image tracking based on the AliceVision photogrammetry computer vision framework through Meshroom software, and reconstructing the terrain based on the SFM and MVS methods; S30, saving the terrain reconstructed in the step S20 as an obj format file, and processing the reconstructed terrain through Meshlab software; S40, exporting the processed file in the step S30 as a three-dimensional cloud map file in the Polygon File Format format, and then processing it through drawing code or drawing software to generate terrain contour lines.

[0009] Furthermore, step S10 includes taking photos after the water tank is filled with water and taking photos underwater. In order to ensure the accuracy of the reconstructed terrain, it is recommended that the shooting equipment be a mobile phone or camera with a pixel of not less than 1200MP, and photos should be taken from the front, back, left and right of the water tank, with the overlap between single photos being greater than 60%.

[0010] Furthermore, if taking photos underwater, let it sit for a while after flushing before taking photos underwater, and adjust the photo color, improve comparison and enhance image sharpness after taking photos.

[0011] Furthermore, the specific steps of step S20 are as follows:

[0012] S201. Open Meshroom software;

[0013] S202, importing a number of images into Image Gallery;

[0014] S203. Click the Start option;

[0015] S204: Display the terrain reconstructed image in the 3D Viewer.

[0016] Furthermore, in step S30, the Meshlab software processes the reconstructed terrain by specifically cutting, removing unnecessary debris, smoothing the terrain, and zooming in and out.

[0017] Furthermore, during the initial reconstruction of the photographs, standard objects were placed on the sand bed, and the model was scaled according to the ratio of the modeled object size to the actual size. Adjustments were made through the Transform Scale option in the Meshlab software Filters. The modeled terrain was then cropped and corrected, retaining the parts that were needed by individuals, and the redundant modeled parts were deleted through the Delete Selected Vertices option.

[0018] In a second aspect, the present invention further provides a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program implements the above method when executed by a processor.

[0019] In a third aspect, the present invention further provides an electronic terminal, comprising: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal executes the method as described above.

[0020] Compared with the prior art, the laboratory scour topography acquisition method, medium and terminal provided by the present invention have at least the following beneficial effects:

[0021] At present, the common scour terrain acquisition equipment used for water tanks is mainly underwater three-dimensional sonar scanners, underwater laser scanners, dot matrix scanners, etc., but the scanning equipment is expensive, and the post-processing of the scanned terrain is relatively complicated; in addition, if the scour terrain is acquired without terrain scanning equipment, the existing method mainly uses oblique photogrammetry technology for three-dimensional reconstruction, and uses commercial software to process two-dimensional images and perform three-dimensional reconstruction to obtain the scour terrain. This method requires a large amount of work and has a low efficiency in terrain reconstruction. In addition, this method can only obtain terrain changes within a small range, and cannot obtain scour terrain in a large range. The accuracy of the acquired scour terrain is also low. The present invention has a simple process and reliable results. It uses a combination of Meshroom and Meshlab software to reconstruct terrain. The laboratory water tank scour terrain reconstruction workflow and post-processing based on the SFM method reduces the terrain calibration point correction work before reconstruction, and can achieve rapid reconstruction and high-precision reconstruction of terrain in a large range. The terrain reconstruction takes a short time, is highly operable, and has high terrain reconstruction efficiency and high accuracy of the acquired scour terrain. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the scheme of the present invention, a brief introduction is given below to the figures required for use in the description of the embodiments. Obviously, the figures described below are some embodiments of the present invention. For ordinary technicians in this field, other figures can be obtained based on these figures without paying any creative work.

[0023] Figure 1 A flow chart of a method for obtaining laboratory scour topography provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of an interface for importing a picture into Meshroom software and preparing for reconstruction in a laboratory scour terrain acquisition method provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of an interface of a terrain reconstruction process in a laboratory scour terrain acquisition method provided by an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of an interface after terrain reconstruction is completed in a laboratory scour terrain acquisition method provided by an embodiment of the present invention;

[0027] Figure 5 A schematic diagram of an interface for processing the reconstructed terrain using Meshlab software in a laboratory scour terrain acquisition method provided by an embodiment of the present invention;

[0028] Figure 6 A three-dimensional cloud map generated by processing with Meshlab software in a laboratory scour terrain acquisition method provided in an embodiment of the present invention;

[0029] Figure 7 A terrain contour map is generated after processing a three-dimensional cloud map in a laboratory scour terrain acquisition method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] The present invention provides a laboratory scour topography acquisition method, which is applied to the scour topography acquisition process of a water tank. The laboratory scour topography acquisition method comprises the following steps:

[0033] S10, obtaining high-definition two-dimensional photos of the scour terrain; S20, performing three-dimensional reconstruction and image tracking based on the AliceVision photogrammetry computer vision framework through Meshroom software, and reconstructing the terrain based on the SFM and MVS methods; S30, saving the terrain reconstructed in step S20 as an obj format file, and processing the reconstructed terrain through Meshlab software; S40, exporting the processed file in step S30 as a three-dimensional cloud map file in the Polygon File Format format, and then processing it through Matlab software or Python code to generate terrain contour lines.

[0034] The terrain reconstruction of the present invention takes a short time, has strong operability, and has high terrain reconstruction efficiency and high accuracy of the acquired scour terrain.

[0035] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0036] The present invention provides a laboratory scour topography acquisition method, which is applied to the scour topography acquisition process of a physical model experimental flume. Figures 1 to 7 The laboratory scour topography acquisition method comprises the following steps:

[0037] S10. Obtain high-definition two-dimensional photos of the erosion terrain.

[0038] Specifically, there are two ways to obtain two-dimensional terrain images, including taking photos after the trough is filled with water and taking photos underwater. The above two methods can achieve the reconstruction of scour terrain in a larger range. If the terrain is scoured three-dimensionally after the trough is filled with water, this method can meet the acquisition of scour terrain within a maximum range of 4m in length and 2m in width.

[0039] Furthermore, in this embodiment, the two-dimensional image of the scour terrain can be obtained by taking pictures with mobile phones, cameras and other photographic equipment. In order to ensure a better reconstruction effect, the pixel of the photographing equipment is not less than 1200MP. At the same time, the scour terrain needs to be obtained from different heights and directions. The terrain should be photographed from four directions, front, back, left and right, of the water tank and at two different heights in each direction. When taking pictures of the terrain in each direction and at each height, the overlap between single photos is greater than 60% to ensure the best recognition effect of the terrain. For areas with more complex terrain, multiple shots of local images can be taken to improve the accuracy of three-dimensional reconstruction.

[0040] In this embodiment, if the terrain photography is performed after the water tank is filled with water, the picture does not need to be processed and the terrain reconstruction of step S20 can be performed directly. If underwater photography is performed, the underwater pictures need to be processed to a certain extent before three-dimensional modeling can be performed. The reason is that due to the refraction of light underwater and other reasons, the color of the picture will change, and the mud in the tank makes the water body turbid, which will affect the subsequent terrain reconstruction. Therefore, if underwater photography is performed, it is necessary to let it stand for a period of time after flushing to ensure that the water body is clear before taking underwater photos. After taking the photos, the photo color adjustment, improved comparison, and enhanced image sharpening must be performed before the next step of terrain reconstruction.

[0041] S20. Three-dimensional reconstruction and image tracking are performed using Meshroom software based on the AliceVision photogrammetry computer vision framework, and terrain reconstruction is performed based on the SFM and MVS methods.

[0042] Specifically, Meshroom is open source software for 3D reconstruction. It performs 3D reconstruction and image tracking based on the AliceVision photogrammetry computer vision framework, and terrain reconstruction based on SFM and MVS (Multi-View Stereo). The basic idea is to generate a 3D model by analyzing multiple overlapping images. Compared with other software, this software does not require image calibration and processing for terrain reconstruction, which saves a lot of time.

[0043] Furthermore, in this embodiment, the basic operation process is as follows:

[0044] S201. Open Meshroom software;

[0045] S202, import multiple pictures into Image Gallery;

[0046] S203. Click the Start option;

[0047] S204. Display in a 3D Viewer.

[0048] S30. The terrain reconstructed in step S20 is automatically saved as an obj format file by the software, and the reconstructed terrain is processed by Meshlab software.

[0049] Specifically, for the terrain reconstructed by Meshroom, the software automatically saves it as an obj format file, which is then opened with Meshlab software for processing. Meshlab can process the terrain point cloud and reconstructed terrain generated by Meshroom, including cropping, removing unnecessary debris, terrain smoothing, and zooming in and out, etc., which can make the reconstructed terrain more complete and regular without affecting the accuracy.

[0050] S40, exporting the file processed in step S30 into a three-dimensional cloud image file in the Polygon File Format format, and then processing it through Matlab software or Python code to generate terrain contour lines.

[0051] Specifically, after the modeling is processed in Meshlab, since it is impossible to directly generate a terrain contour cloud map, the file can be exported as a Polygon File Format file, and then processed through Matlab, Python code and other drawing software to generate terrain contour lines.

[0052] The following is combined with Figures 1 to 7 The workflow of the laboratory scour topography acquisition method provided by the embodiment of the present invention is described as follows:

[0053] First, complete the flushing experiment in the indoor water tank. After the flushing experiment is completed, drain the water tank and expose the flushing terrain to the water surface, take a photo of the flushing terrain. The shooting range is determined by yourself according to the required terrain. Then put the pictures in a folder and import them into the Meshroom software. The imported picture format can be PNG, JPG and other software-supported formats. Then, on the software work page, click Start to start. After the reconstruction is completed, the software will display the camera movement trajectory according to the photo angle and SFM algorithm, and complete the terrain reconstruction. After reconstruction, it is regarded as a point cloud map. The software will perform interpolation calculations based on the point cloud data to reconstruct the terrain, and map the texture obtained by shooting to reconstruct the real texture.

[0054] Since the wall of the water tank and other redundant parts will be reconstructed after the terrain reconstruction, it is necessary to process them in Meshlab. The main operations are scaling, adjusting the coordinate axis, and trimming the terrain shape. Since the key points were not calibrated in the early stage, sometimes the modeling size is not the complete prototype size, so it is necessary to scale the size in the Meshlab software. When taking pictures of the scour terrain in the early stage, standard objects can be placed on the sand bed, and the model can be scaled according to the size of the modeling object and the ratio of the actual size. The Transform Scale option in the Meshlab software Filters is used for adjustment, and then the modeling terrain is cropped and corrected. The desired part can be retained, and the redundant modeling part can be deleted through the Delete SelectedVertices option in the software;

[0055] The adjusted point cloud image can then be exported to the xyz file format, which can store point cloud information. The exported point cloud data can be used for drawing in drawing software or drawing code, and the data can be post-processed to achieve fast and high-accuracy terrain processing without scanning equipment.

[0056] An embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, any one of the methods in the present embodiment is implemented.

[0057] An embodiment of the present invention further provides an electronic terminal, comprising: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal executes any one of the methods in this embodiment.

[0058] The computer-readable storage medium in this embodiment can be understood by ordinary technicians in this field: all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

[0059] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication with each other. The memory is used to store computer programs, the communication interface is used to communicate, and the processor and the transceiver are used to run computer programs so that the electronic terminal executes each step of the above method.

[0060] The laboratory scour terrain acquisition method, medium and terminal described in the above embodiment are compared with the prior art. The scour terrain acquisition equipment commonly used in water tanks is mainly underwater three-dimensional sonar scanners, underwater laser scanners, dot matrix scanners, etc., but the scanning equipment is expensive, and the post-processing of the scanned terrain is relatively complicated; in addition, if the scour terrain acquisition without terrain scanning equipment is to be carried out, the existing method is mainly to use oblique photogrammetry technology for three-dimensional reconstruction, and use commercial software to process two-dimensional images and perform three-dimensional reconstruction to obtain the scour terrain. This method requires a large amount of work and has a low efficiency in terrain reconstruction. In addition, this method can only obtain terrain changes within a small range, and cannot obtain scour terrain in a large range. The accuracy of the acquired scour terrain is also low. The present invention has a simple process and reliable results. It uses a combination of Meshroom and Meshlab software to reconstruct terrain. The workflow and post-processing of laboratory water tank scour terrain reconstruction based on the SFM method reduce the correction work of terrain calibration points before reconstruction, and can achieve rapid reconstruction and high-precision reconstruction of terrain in a large range. The terrain reconstruction takes a short time, is highly operable, and has high efficiency in terrain reconstruction and accuracy of the acquired scour terrain.

[0061] Obviously, the embodiments described above are only preferred embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are shown in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific embodiments, or to perform equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A method for obtaining laboratory scour topography, characterized in that: The following steps are involved: S10, obtaining high-definition two-dimensional photos of the scour terrain; S20, 3D reconstruction and image tracking based on AliceVision photogrammetry computer vision framework using Meshroom software, and terrain reconstruction based on SFM and MVS methods; S30, saving the terrain reconstructed in step S20 as an obj format file, and processing the reconstructed terrain by Meshlab software; S40, exporting the file processed in step S30 into a three-dimensional cloud map file in a Polygon File Format or an xyz format, and then processing it through a drawing code or a drawing software to generate terrain contour lines.

2. A method for obtaining laboratory scour topography according to claim 1, characterized in that: The step S10 includes taking photos after the water tank is filled with water and taking photos underwater. The shooting equipment is a mobile phone or camera with a pixel resolution of not less than 12 million MP. Photos are taken from different heights in front, behind, left and right of the water tank, and the overlap between single photos is greater than 60%.

3. A method for obtaining laboratory scour topography according to claim 2, characterized in that: If you take photos underwater, let it sit for a while after flushing before taking photos underwater. After taking photos, adjust the color of the photos, improve the comparison, and enhance the sharpness of the images.

4. A method for obtaining laboratory scour topography according to claim 1, characterized in that: The specific steps of step S20 are as follows: S201. Open Meshroom software; S202, importing a number of images into Image Gallery; S203. Click the Start option to automatically rebuild the terrain; S204: Display the terrain reconstructed image in the 3D Viewer.

5. A method for obtaining laboratory scour topography according to claim 1, characterized in that: In step S30, the Meshlab software processes the reconstructed terrain by clipping, removing unnecessary debris, smoothing the terrain, and zooming in and out.

6. A method for obtaining laboratory scour topography according to claim 5, characterized in that: In the initial reconstruction of the terrain, standard objects are placed on the sand bed, and the model is scaled according to the ratio of the modeled object size to the actual size. The Transform Scale option in the Meshlab software Filters is used for adjustment. Then the modeled terrain is cropped and corrected, the necessary parts are retained, and the redundant modeled parts are deleted through the Delete Selected Vertices option.

7. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

8. An electronic terminal, characterized in that: include: Processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal executes the method according to any one of claims 1 to 6.

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