Multi-scale submarine pipeline laying construction grid screening method and system

Abstract

The invention discloses a multi-scale submarine pipeline laying construction grid screening method and system. The method comprises the following steps: (1) map acquisition: reading a seabed elevation map of a seabed area to be screened; (2) edge detection: monitoring edge contours in the elevation image by adopting an edge detection algorithm to obtain edge coordinates, dividing elevation image blocks into areas according to the edge contours, and judging the types of the areas; (3) rasterization of different scales is carried out on the seabed elevation map of the to-be-screened seabed area, grid screening is carried out according to the sequence of the scales from large to small, grid screening of each scale is carried out, grids with the average gradient smaller than the preset gradient threshold value of the grid category in the to-be-screened area are reserved, and the to-be-screened seabed area is obtained; and taking other areas as to-be-screened areas screened by the next small-scale grids, and finally combining the retained grids with different scales into a to-be-constructed seabed area. According to the invention, the resolution can be adjusted by setting the size of the grid as required, and both the screening speed and the screening precision are considered.

Description

Technical Field

[0001] The present invention belongs to the technical field of subsea construction, and more specifically, relates to a multi-scale grid screening method and system for subsea pipeline laying construction. Background Art

[0002] Subsea pipeline laying is a basic project for many subsea constructions. For example, operations such as oil and gas transportation, power transmission, and communication network deployment all require laying pipelines subsea. The geological conditions subsea are very different from those on land. The subsea sediment layer is affected by various factors such as seawater erosion, water flow, and organisms. The sediment is mainly fine particles that slowly settle, such as clay minerals and the remains of micro-organisms. Therefore, the subsea sediment layer is thicker, softer, and less stable. It is also more difficult to select the location area for subsea pipeline laying construction. Firstly, the exploration difficulty is relatively large. It is difficult to obtain subsea geological information, and there are complex terrains such as hills, mountains, seabeds, and trenches subsea. If construction is only carried out in flat areas, it may be necessary to bypass complex terrains, resulting in a sharp increase in costs. If pipeline laying is carried out in areas with complex terrains, the risk of equipment damage caused by geological activities such as landslides will increase.

[0003] Currently, when laying subsea pipelines, it is necessary to carefully survey the subsea area to be constructed. For example, a multi-beam imaging system and a multi-channel seismic system are used to conduct high-resolution detection of the subsea geomorphology and geological profile, and carefully identify and explore geological features such as subsea landslides, such as Chinese patent document CN116188964A. In order to ensure the construction safety and use safety of subsea pipelines and obtain subsea geomorphology and geological profile data, these methods require a large amount of time cost and economic cost when the construction scope is large, and the large amount of data makes the screening and analysis of the subsea area complex. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement requirements of the prior art, the present invention provides a multi-scale grid screening method and system for subsea pipeline laying construction. The purpose is to judge the stability degree of the sediment layer through multi-scale grid screening, combined with the terrain area category and slope information, taking into account both the screening speed and accuracy, and obtain the subsea area to be constructed that meets the construction conditions, thereby solving the technical problem that the prior art requires a large amount of time cost and economic cost for the subsea area to be constructed that meets the construction conditions for large-scale subsea pipeline construction.

[0005] To achieve the above object, according to one aspect of the present invention, a multi-scale grid screening method for subsea pipeline laying construction is provided. Based on the subsea elevation information, it specifically includes the following steps:

[0006] (1) Map acquisition: Read the seabed elevation map of the seabed area to be screened; each pixel of the elevation image includes plane coordinate information and elevation value information, where the plane coordinate information is used to represent the corresponding position of the three-dimensional terrain to be reconstructed, and the elevation value information is used to represent the altitude information of the three-dimensional terrain to be reconstructed at this position;

[0007] (2) Edge detection: Use an edge detection algorithm on the elevation image obtained in step (1) to monitor the edge contours in the image to obtain edge coordinates, divide the elevation image blocks into regions according to the edge contours, and determine the category of the region;

[0008] (3) Perform rasterization of the seabed elevation map of the seabed area to be screened obtained in step (1) at different scales, and the resolution of the raster is d x ×d y , perform raster screening in the order from large to small scale. For each scale of raster screening, retain the rasters in the area to be screened whose average slope is less than the preset slope threshold of this raster category, and use other areas as the area to be screened for the next smaller scale of raster screening. Finally, merge the retained rasters of different scales into the seabed area to be constructed.

[0009] Preferably, for the multi-scale raster screening method for seabed pipeline laying construction, the scale of raster screening in step (3) is determined according to the following method:

[0010] S1. Determine the screening scale range and step size; the screening scale range, that is, the value range of the raster resolution d x ×d y : For the scale change magnitudes of d x and d y , they are determined by the step size functions λ x and λ y respectively;

[0011] S2. According to the screening scale range and step size obtained in step S1, determine the raster resolution of the l-th raster screening in descending order

[0012] Preferably, for the multi-scale raster screening method for seabed pipeline laying construction, the specific steps of the l-th raster screening are as follows:

[0013] (3-1) Map rasterization: Rasterize the seabed elevation map of the area to be screened, and the resolution of the raster is where is the number of pixels in the horizontal direction of the raster for the l-th raster screening, is the number of pixels in the vertical direction of the raster for the l-th raster screening; when the pixels in the raster are of the same category, use this category as the category of the raster, and use this raster as the raster to be screened;

[0014] (3-2) Grid screening: For the grids to be screened obtained in step (3-1), calculate the average slope of the grid according to the elevation difference between it and the surrounding grids, and use the grids with an average slope less than the preset slope threshold of the grid category as the laying construction grids for pipeline laying route planning; the preset slope threshold of the grid category is determined according to the principle that the greater the average elevation value of the seabed area of the category, the greater the preset slope.

[0015] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, the slope is used to characterize the change rate of the grid elevation in a certain direction, and can be calculated by the ratio of the difference between the average elevation of the surrounding grids and this grid to the distance of the grid center.

[0016] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, the average slope is used to characterize the average value of the change rate of the grid elevation in each direction; the average slope of the grid The calculation method is as follows:

[0017]

[0018] Among them, S (i,j) is the slope of this grid relative to the surrounding grids. The relative coordinates of this grid are (0, 0), and the coordinates of the surrounding grids are (i, j), where i = -1, 0, 1, j = -1, 0, 1, and i and j are not both 0 at the same time.

[0019] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, the slope S of the grid relative to the surrounding grids (i,j) The calculation method is as follows:

[0020]

[0021] Among them is the average elevation of the grid with coordinates (i, j), is the average elevation of this grid. The average elevation of the grid is calculated according to the following method:

[0022]

[0023] Among them, h is the elevation value of the pixel in the grid.

[0024] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, the category of the area in step (2) is used to characterize the terrain category, and the category can be predefined or classified by using a trained and converged classifier.

[0025] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, when the elevation image of the three-dimensional terrain to be reconstructed is a color image, the original image or grayscale image is used for edge detection. The preferred edge detection algorithm is the Sobel algorithm, which uses a discrete difference operator to calculate the gradient of the grayscale value of the image pixels and identifies edges through convolution operations in the horizontal and vertical directions.

[0026] Preferably, in the multi-scale seabed pipeline laying construction grid screening method, the elevation value is the grayscale value of the image. When the elevation image of the three-dimensional terrain to be reconstructed is a color image, the pixel color is represented in RGB format, and the grayscale value corresponding to the RGB value is used as the elevation value of the pixel.

[0027] According to another aspect of the present invention, a multi-scale seabed pipeline laying construction grid screening system is provided. The system is an electronic device or a non-transitory computer-readable storage medium;

[0028] The electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. The characteristic is that when the processor executes the program, it implements the steps of the multi-scale seabed pipeline laying construction grid screening method provided by the present invention.

[0029] The non-transitory computer-readable storage medium stores a computer program thereon. The characteristic is that when the computer program is executed by the processor, it implements the steps of the multi-scale seabed pipeline laying construction grid screening method provided by the present invention.

[0030] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0031] The seabed pipeline laying construction grid screening method provided by the present invention is based on the seabed elevation map. Through grid screening at different scales, the resolution can be adjusted according to needs by setting the grid size, taking into account both the screening speed and screening accuracy, and quickly and carefully searching for the seabed area to be constructed that meets the construction conditions from the seabed area to be screened.

[0032] In the preferred solution, the stability degree of the sediment layer is judged by combining the regional category and the slope of the grid area, and the seabed terrain and geomorphic information are comprehensively used to adaptively screen the grids suitable for seabed pipeline laying construction, so as to effectively control the cost on the premise of ensuring construction safety and use safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an example of the seabed terrain elevation data adopted in the embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of the seabed terrain adopted in the embodiment of the present invention;

[0035] Figure 3 It is a schematic diagram of the raster category matrix after rasterization of the map in the embodiment of the present invention.

[0036] Figure 4 It is a schematic diagram of the raster slope matrix data in the embodiment of the present invention. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The multi-scale undersea pipeline laying construction raster screening method provided by the present invention is based on undersea elevation information and specifically includes the following steps:

[0039] (1) Map acquisition: Read the undersea elevation map of the undersea area to be screened; each pixel point of the elevation image includes plane coordinate information and elevation value information, and the plane coordinate information is used to represent the corresponding position of the three-dimensional terrain to be reconstructed, and the elevation value information is used to represent the altitude information of the position of the three-dimensional terrain to be reconstructed at this position;

[0040] In a preferred solution, the elevation value is the image gray value. When the elevation image of the three-dimensional terrain to be reconstructed is a color image, the pixel color is represented in RGB format, and the gray value corresponding to the RGB value is used as the elevation value of the pixel;

[0041] (2) Edge detection: Use an edge detection algorithm to monitor the edge contours in the elevation image obtained in step (1) to obtain edge coordinates, divide the elevation image blocks into regions according to the edge contours, and judge the category of the region;

[0042] When the elevation image of the three-dimensional terrain to be reconstructed is a color image, the original image or gray image is used for edge detection. The preferred edge detection algorithm is: Sobel algorithm, which uses a discrete difference operator to calculate the gradient of the pixel gray value of the image, and identifies the edge through convolution operations in the horizontal and vertical directions; the Sobel algorithm has good robustness to images with strong noise, and can perform edge detection quickly at the same time, and is suitable for making quick edge detection of elevation images for complex terrain characteristics.

[0043] The category of the region is used to characterize the terrain category, and the category can be predefined or classified using a trained and converged classifier;

[0044] (3)Rasterize the seabed elevation map of the seabed area to be screened obtained in step (1) at different scales, with the resolution of the raster being d x ×d y , and perform raster screening in the order from the largest scale to the smallest. For the raster screening at each scale, retain the rasters in the area to be screened whose average slope is less than the preset slope threshold of the raster category, and use the other areas as the areas to be screened for the raster screening at the next smaller scale. Finally, merge the retained rasters at different scales into the seabed area to be constructed.

[0045] The scale of raster screening is determined as follows:

[0046] S1. Determine the screening scale range and step size; the screening scale range, that is, the value range of the raster resolution d x ×d y : For the magnitude of the scale change of d x and d y , they are determined by the step functions λ x and λ y respectively; the types of step functions include but are not limited to constant functions, linear functions, and exponential functions; when it is a constant function, that is, the change in the raster resolution of raster screening is a fixed value; when it is a linear function, that is, the change in the raster resolution of raster screening changes linearly with the number of raster screening times, usually decreasing linearly; when it is an exponential function, that is, the change in the raster resolution of raster screening changes exponentially with the number of raster screening times.

[0047] S2. According to the screening scale range and step size obtained in step S1, determine the raster resolution of the l-th raster screening in descending order

[0048] The resolution of the raster is determined according to the calculation accuracy. The higher the calculation accuracy, the higher the resolution of the raster, that is and the smaller the values, so as to achieve multi-scale analysis. When the area of the laying construction raster obtained by screening is not sufficient to meet the construction requirements, the resolution of the raster can be increased, so as to combine the advantages of accuracy and speed and quickly obtain the seabed area to be constructed that meets the construction requirements.

[0049] The specific steps of the l-th raster screening are as follows:

[0050] (3-1) Map rasterization: Rasterize the seabed elevation map of the area to be screened, and the resolution of the raster is where is the number of pixels in the horizontal direction of the raster for the l-th raster screening, is the number of pixels in the vertical direction of the raster for the l-th raster screening; when the pixels in the raster are of the same category, take this category as the category of the raster and take this raster as the raster to be screened;

[0051] If the cell categories within a grid are different, it indicates that the grid is in a geological boundary area where the sediment layer is unstable and is not used as a laying construction grid; when planning the pipeline route, the construction costs, construction, and usage risks of these grids are considered. Priority is given to the internal area grids of the same category, which can effectively search for areas with stable sediment layers and reduce construction costs and risks.

[0052] (3-2) Grid screening: For the grids to be screened obtained in step (3-1), calculate the average slope of the grid based on the elevation difference between it and the surrounding grids, and use the grids with an average slope less than the preset slope threshold of the grid category as laying construction grids for pipeline laying route planning; the preset slope threshold of the grid category is determined according to the principle that the greater the average elevation value of the seabed area of the category, the greater the preset slope.

[0053] The slope is used to characterize the change rate of the grid elevation in a certain direction, and specifically can be calculated by the ratio of the difference between the average elevation of the surrounding grids and this grid to the distance of the grid center; the average slope is used to characterize the average value of the change rates of the grid elevation in all directions; the average slope of the grid The calculation method is as follows:

[0054]

[0055] Among them, S (i,j) is the slope of this grid relative to the surrounding grids. The relative coordinates of this grid are (0,0), and the coordinates of the surrounding grids are (i,j), where i = -1, 0, 1, j = -1, 0, 1, and i and j are not both 0 at the same time; the calculation method is as follows:

[0056]

[0057] Among them is the average elevation of the grid with coordinates (i,j), is the average elevation of this grid. The average elevation of the grid is calculated according to the following method:

[0058]

[0059] Among them, h is the elevation value of the pixel within the grid.

[0060] The following are examples:

[0061] The method for screening laying construction grids for submarine pipelines provided in this embodiment is based on submarine elevation information and specifically includes the following steps:

[0062] (1) Map acquisition: Read the seabed elevation map of the seabed area to be screened; each pixel of the elevation image includes plane coordinate information and elevation value information. The plane coordinate information is used to represent the corresponding position of the three-dimensional terrain to be reconstructed, and the elevation value information is used to represent the altitude information of this position of the three-dimensional terrain to be reconstructed; load the selected file path, and use the QImage object to complete the storage of the elevation image and obtain the width w I and height h I of it.

[0063] The elevation value is the image grayscale value. In this embodiment, the elevation image of the three-dimensional terrain to be reconstructed is a color image, and the pixel color is represented in RGB format, and the grayscale value corresponding to the RGB value is used as the elevation value of the pixel; the calculation method is as follows:

[0064] g = 0.299×R + 0.587×G + 0.114×B

[0065] where g is the grayscale value of this pixel, R is the red component of this pixel, G is the green component of this pixel, and B is the blue component of this pixel.

[0066] (2) Edge detection: Use the edge detection algorithm on the elevation image obtained in step (1) to monitor the edge contours in the image to obtain edge coordinates, divide the elevation image blocks into regions according to the edge contours, and judge the categories of the regions;

[0067] The edge detection algorithm used in this embodiment is: Sobel algorithm; the categories of regions are obtained by training a convolutional neural network. The region categories in this embodiment include:

[0068] Category 1: Shallow sea area, characterized by a low elevation and a relatively small corresponding slope threshold;

[0069] Category 2: Deep sea trench area, characterized by a deep elevation and a relatively large corresponding slope threshold;

[0070] Category 3: Seamount area, characterized by a high elevation and a relatively large slope threshold.

[0071] (3) Perform rasterization of different scales on the seabed elevation map of the seabed area to be screened obtained in step (1), and the resolution of the raster is d x ×d y , perform raster screening in the order from large to small in scale. For each scale of raster screening, retain the rasters in the area to be screened whose average slope is less than the preset slope threshold of this raster category, and use other areas as the area to be screened for the next smaller scale of raster screening. Finally, merge the retained rasters of different scales into the seabed area to be constructed.

[0072] The scale of raster screening is determined according to the following method:

[0073] S1. Determine the screening scale range and step size; the screening scale range, i.e., the grid resolution d x ×d y The value range of For d x and d y The scale change sizes of are respectively determined by the step functions λ x and λ y ; the step function can be a constant, i.e., the grid resolution change for grid screening is a fixed value, a linear function, i.e., the grid resolution change for grid screening changes linearly with the number of grid screening times, usually linearly decreasing; or an exponential function, i.e., the grid resolution change for grid screening changes exponentially with the number of grid screening times, and so on.

[0074] S2. According to the screening scale range and step size obtained in step S1, determine the grid resolution of the l-th grid screening in descending order In this embodiment, the step function adopts a constant, i.e.,

[0075]

[0076] where λ x , λ y are constants.

[0077] The specific steps of the l-th grid screening are as follows:

[0078] (3-1) Map rasterization: rasterize the seabed elevation map of the area to be screened, and the resolution of the grid is where is the number of pixels in the horizontal direction of the grid for the l-th grid screening, is the number of pixels in the vertical direction of the grid for the l-th grid screening; when the categories of the pixels in the grid are the same category, take this category as the category of this grid, and take this grid as the grid to be screened;

[0079] As Figures 1 to 3 shown, Figure 1 is the seabed terrain elevation data, Figure 2 is the schematic diagram of the terrain, Figure 3 is the category data of the rasterized area. In this rasterization, the resolution is 10×10, and the corresponding values in the matrix are calculated using the gray values of the topographic map.

[0080] (3-2) Grid screening: For the grids to be screened obtained in step (3-1), calculate the average slope of the grid according to the elevation difference between it and the surrounding grids, and take the grids with an average slope less than the preset slope threshold of the grid category as the laying construction grids for pipeline laying route planning; the preset slope threshold of the grid category is determined according to the average elevation value of the seabed area of the category, following the principle that the larger the average elevation value, the larger the preset slope.

[0081] The slope is used to characterize the change rate of the grid elevation in a certain direction, and can be specifically calculated by the ratio of the difference between the average elevation of the surrounding grids and this grid to the distance of the grid center; the average slope is used to characterize the average value of the change rates of the grid elevation in all directions; the average slope of the grid The calculation method is as follows:

[0082]

[0083] Among them, S (i,j) is the slope of this grid relative to the surrounding grids. The relative coordinates of this grid are (0,0), and the coordinates of the surrounding grids are (i,j), where i = -1, 0, 1, j = -1, 0, 1, and i and j are not both 0 at the same time; the calculation method is as follows:

[0084]

[0085] Among them is the average elevation of the grid with coordinates (i,j), is the average elevation of this grid, and the average elevation of the grid is calculated according to the following method:

[0086]

[0087] Among them, h is the elevation value of the pixel in the grid.

[0088] Generate the following categories according to the calculation results:

[0089] Category 1: Shallow sea area (low elevation, small slope threshold)

[0090] Category 2: Deep trench area (deep elevation, large slope threshold)

[0091] Category 3: Seamount area (high elevation, large slope threshold)

[0092] Set the thresholds as: the preset slope threshold for the Category 1 (shallow sea) area is S_threshold1 = 0.5, the preset slope threshold for the Category 2 (deep trench) area is S_threshold2 = 1.0, and the preset slope threshold for the Category 3 (seamount) area is S_threshold3 = 1.5.

[0093] The classified matrix is as follows Figure 3 .

[0094] From this, a topographic change schematic diagram of this area can be seen. The calculated slope value schematic diagram is as follows Figure 4 .

[0095] This embodiment supports multi-scale slope analysis. By calculating the slope at different spatial resolutions, flat terrain areas at different scales can be identified. Through multi-scale analysis, the local topographic features can be evaluated in detail, while also taking into account the overall topographic evaluation of a larger area. Starting from the rough large-scale identification, and then gradually zooming in to analyze the local area to obtain more detailed topographic details. The system marks the areas with slope values lower than the set threshold as flat areas according to the calculated slope values. The identification process is based on pixel-level slope data, and the connectivity and integrity of the flat areas are determined through a spatial proximity algorithm. The multi-scale analysis improves the adaptability of the system, which can handle large-scale mapping tasks and also perform high-precision analysis in specific areas, avoiding missing small-scale flat areas. This module uses the distribution law of slope values, combined with topographic continuity and geomorphic features, to accurately extract flat terrain. The accuracy of flat terrain identification is high, which can effectively handle diverse seabed geomorphic features and is particularly suitable for engineering applications such as pipeline laying and submarine cable laying that require flat terrain. After dividing whether it belongs to flat terrain according to the threshold, it is also necessary to analyze the elevation change of the flat area. When the elevation change is small, it indicates that the area is a flat and gully-free area, suitable for operations such as submarine pipeline laying.

[0096] It is easy for those skilled in the art to understand that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-scale grid screening method for submarine pipeline installation, characterized in that: Based on the seabed elevation information, the following steps are specifically included: (1) Map acquisition: reading a seabed elevation map of the seabed area to be screened; each pixel point of the elevation image includes plane coordinate information and elevation value information, wherein the plane coordinate information is used to represent the corresponding position of the three-dimensional terrain to be reconstructed, and the elevation value information is used to represent the altitude information of the position of the three-dimensional terrain to be reconstructed; (2) Edge detection: using an edge detection algorithm to monitor the edge contours in the elevation image obtained in step (1) to obtain edge coordinates, dividing the elevation image blocks into regions according to the edge contours and determining the categories of the regions; (3) The seafloor elevation map of the seafloor area to be screened obtained in step (1) is rasterized at different scales, and the resolution of the raster is d x ×d y , grid screening is performed in order of scale from large to small. For each scale of grid screening, grids whose average slope is less than the preset slope threshold of the grid category are retained in the area to be screened, and other areas are used as the area to be screened for the next smaller scale of grid screening. Finally, the retained grids of different scales are merged into the seabed area to be constructed.

2. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 1, characterized in that: Step (3) The scale of grid screening is determined as follows: S1, determine the screening scale range and step size; the screening scale range, i.e., the grid resolution d x ×d y The value range of is: For d x and d y The scale change size is determined by the step size function λ x and λ y Sure; S2. According to the screening scale range and step size obtained in step S1, determine the grid resolution of the first grid screening in descending order.

3. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 2, characterized in that: The specific steps of the first grid screening are: (3-1) Map rasterization: The seafloor elevation map of the area to be screened is rasterized with a resolution of in is the number of pixels in the horizontal direction of the grid screened for the lth time, is the number of pixels in the vertical direction of the grid screened for the lth time; when the categories of the pixels in the grid are the same, the category is taken as the category of the grid, and the grid is taken as the grid to be screened; (3-2) Grid screening: For the grid to be screened obtained in step (3-1), the average slope of the grid is calculated based on the difference in elevation between the grid and the surrounding grids, and the grid with an average slope less than the preset slope threshold of the grid category is used as the laying construction grid for pipeline laying route planning; the preset slope threshold of the grid category is determined based on the average elevation value of the seabed area of ​​the category and the principle that the larger the average elevation value, the larger the preset slope.

4. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 3, characterized in that: The slope is used to characterize the rate of change of grid elevation along a certain direction, and can be calculated by the ratio of the difference between the average elevation of the surrounding grids and the grid to the distance from the grid center.

5. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 4, characterized in that: The average slope is used to characterize the average rate of change of the grid elevation in all directions; the average slope of the grid The calculation method is as follows: Among them, S (i,j) is the slope of the grid relative to the surrounding grids. The relative coordinates of the grid are (0,0), and the coordinates of the surrounding grids are (i,j), i = -1,0,1, j = -1,0,1, and i and j are not 0 at the same time.

6. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 5, characterized in that: The slope S of the grid relative to the surrounding grids (i,j) The calculation method is as follows: in is the average elevation of the grid with coordinate (i, j), is the average elevation of the grid. Calculate as follows: Among them, h is the elevation value of the pixel in the raster.

7. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 1, characterized in that: The category of the area in step (2) is used to characterize the terrain category. The category can be pre-defined or classified using a trained and converged classifier.

8. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 7, characterized in that: When the elevation image of the three-dimensional terrain to be reconstructed is a color image, the original image or grayscale image is used for edge detection. The preferred edge detection algorithm is: Sobel algorithm, which uses a discrete difference operator to calculate the gradient of the grayscale value of the image pixels and identifies the edge through convolution operations in both horizontal and vertical directions.

9. The multi-scale grid screening method for submarine pipeline installation as claimed in claim 1, characterized in that: The elevation value is an image grayscale value. When the elevation image of the three-dimensional terrain to be reconstructed is a color image, the pixel color is represented in RGB format, and the grayscale value corresponding to the RGB value is used as the elevation value of the pixel.

10. A multi-scale grid screening system for submarine pipeline installation, the system being an electronic device or a non-transitory computer-readable storage medium; The electronic device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the multi-scale submarine pipeline laying construction grid screening method as claimed in any one of claims 1 to 9 are implemented. The non-transitory computer-readable storage medium stores a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the multi-scale submarine pipeline installation grid screening method as described in any one of claims 1 to 9.

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