Determination of the distance between the coral island reef beach and sand boundary and the site selection method for dike projects

Abstract

The embodiment of the present invention discloses a method for determining the advance and retreat distance of the beach sand boundary of coral islands and reefs and selecting the site for dike projects. The advance and retreat distance determination method includes: obtaining the beach sand boundary lines of coral islands and reefs in two periods, and taking the beach sand boundary line of the earlier period as the baseline, and taking the beach sand boundary line of the other period as the target boundary line; calculating the closest distance from each target point on the target boundary line to the baseline; taking the centroid of the closed area surrounded by the target boundary line as the azimuth reference point, dividing the full angular range into multiple intervals; and calculating the advance and retreat distance of the coral islands and reefs along the main direction of each interval based on the closest distance of all target points in each interval. This embodiment can accurately express the distance of siltation or erosion of the beach sand boundary line of coral islands and reefs in all directions, and provide data support for the site selection of island and reef dike projects.

Description

Technical Field

[0001] The embodiments of the present invention relate to the fields of island reef embankment engineering, island reef beach regulation and restoration, and in particular to a method for determining the advance and retreat distance of coral island reef beach sand boundaries and selecting a site for an embankment engineering project. Background Art

[0002] The beach sand boundary of coral islands and reefs is the boundary between seawater and land. Since coral islands and reefs are made up of accumulated coral sand and have less vegetation, they are easily affected by climatic conditions such as monsoons and typhoons and hydrological dynamic conditions such as waves and currents, and the spatial morphology of coral islands and reefs is changeable. If the beach sand is silted up, the beach sand boundary of the coral islands and reefs will advance toward the sea. Conversely, if it is eroded, the beach sand boundary of the coral islands and reefs will retreat toward the land. Accurately measuring the spatial distance of coral island and reef beach sand silting up or eroding will help evaluate and predict the future trend of changes in the beach sand boundary of coral islands and reefs, which is of great significance for the planning and construction of coral island and reef embankment projects.

[0003] With the rapid development of remote sensing technology, it has become easier to obtain the boundary lines of coral islands, reefs and beaches from remote sensing images. Most of the existing methods for calculating the distance of coastline change use the cross-section method. The Digital Shoreline Analysis System (DSAS) developed by the United States Geological Survey (USGS) is a widely used digital coastline evolution analysis software. In this software system, it is first necessary to set a baseline of the coastline, and then set several cross-section lines perpendicular to the baseline along the baseline. The distance of the coastline siltation or erosion is determined by calculating the distance between the intersection of the cross-section line and the coastline. Since there are subjective factors in the setting of the baseline, and the cross-section line is only perpendicular to the baseline, the distance between it and the intersection of the two coastlines cannot represent the shortest distance between the two coastlines, resulting in a large error in calculating the distance of coastline change; and since this method calculates the distance of coastline change on each cross-section line, the final statistical results can only describe the maximum, minimum and average distance of change on the entire coastline.

[0004] The Chinese invention patent "Orthogonal Section Method and System for Digital Coastline Evolution Analysis (Patent No. ZL 200910198707.7)" was publicly authorized on December 28, 2011. This method constructs a series of virtual coastlines, uses the arc method to determine the sections orthogonal to the baseline and all coastlines, and then calculates the coastline change distance based on the intersection of the orthogonal section and the coastline. The calculation process of this method is complicated, and if the virtual coastline is not set reasonably, it will also lead to a large error in the calculated coastline change distance.

[0005] The Chinese invention patent "Method for Calculating Coastline Change Rate (Patent No. CN202110668233.9)" published on September 3, 2021, this method obtains the third coordinate data by rotating the coordinate system of the first coordinate coastline data and performing linear interpolation, and then obtains the change distance by subtracting the vertical coordinates of the two coastlines. In order to ensure that the horizontal axis of the rotated coordinate system is parallel to the regional coastline direction, this method will make judgments and segments based on the direction of the coastline, which makes the process complex and computationally intensive.

[0006] The Chinese invention patent "Method for Determining the Setback Distance of Coastline Construction (Patent No. ZL201910118855.7)" was publicly authorized on October 2, 2020. This method calculates the setback distance of coastline construction through a mathematical model. It aims to define a buffer zone of a certain width inland, within which construction is prohibited or certain types of development and construction are restricted. This method is not suitable for calculating the distance of coastline siltation or erosion.

[0007] Since the spatial form of natural coral reefs is mostly circular or elliptical, they are affected differently by climatic conditions and hydrodynamic conditions in different directions, resulting in different distances of siltation or erosion of the coral reef beach sand boundary line in different directions. Existing methods are basically aimed at coastlines, and can only statistically obtain the maximum, minimum and average distances of coastline siltation or erosion, which is difficult to apply to coral reefs, and it is even more difficult to accurately express the distance of siltation or erosion of the coral reef beach sand boundary line in various directions, and cannot provide a basis for the site selection of island reef embankment projects. Summary of the invention

[0008] The embodiment of the present invention provides a method for determining the distance of coral island reef beach sand boundary advance and retreat and selecting the site for embankment engineering to solve the above technical problems.

[0009] In a first aspect, an embodiment of the present invention provides a method for determining the distance of a coral island reef beach sand boundary, comprising:

[0010] Obtain the beach and sand boundary lines of coral islands and reefs in two periods, and use the beach and sand boundary line of the earlier period as the baseline and the beach and sand boundary line of the other period as the target boundary line;

[0011] Calculate the shortest distance from each target point on the target boundary line to the baseline, wherein if the target point is located within the closed area surrounded by the baseline, the shortest distance is positive, representing the erosion distance; if the target point is located outside the closed area surrounded by the baseline, the shortest distance is negative, representing the siltation distance;

[0012] The centroid of the closed area enclosed by the target boundary line is used as the azimuth reference point, and the full angular range is divided into multiple intervals; and based on the shortest distance of all target points in each interval, the advance and retreat distance of the coral islands and reefs along the main direction of each interval is calculated, wherein each advance and retreat distance is used to provide a basis for the site selection of the island reef embankment project.

[0013] In a second aspect, an embodiment of the present invention provides a method for selecting a site for a coral island reef levee project, comprising:

[0014] Using the above method, the advance and retreat distance of the coral reef along the main direction of each interval is obtained;

[0015] If the advance and retreat distance along the main direction of an interval is positive and greater than a relevant threshold, the construction position of the embankment project is determined according to the interval and / or the main direction.

[0016] In a third aspect, an embodiment of the present invention further provides an electronic device, the electronic device comprising:

[0017] one or more processors;

[0018] a memory for storing one or more programs,

[0019] When the one or more programs are executed by the one or more processors, the one or more processors implement the method for determining the advance and retreat distance of the coral island beach sand boundary, or the method for selecting the site for the coral island embankment project described in any embodiment.

[0020] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the advance and retreat distance of the coral island and reef beach sand boundary or the method for selecting a site for a coral island and reef embankment project as described in any embodiment.

[0021] The embodiment of the present invention provides a method for determining the distance of advance and retreat of the coral island reef beach sand boundary. The method directly constructs an orthogonal section for the original coral island reef beach sand boundary line, can accurately determine the distance of advance and retreat of the current boundary line relative to the early boundary line, and measures the distance of advance and retreat according to the angles of different azimuths. This embodiment overcomes the problems that the existing section method needs to introduce a virtual baseline, and the unreasonable setting of the virtual baseline will lead to large errors in the calculated coastline change distance; it also overcomes the problems of complex calculations and large amount of calculations caused by the rotation and segmentation of the coordinate system according to the direction of the coastline; it can quickly and accurately calculate the distance of siltation or erosion in all directions according to the characteristics of islands and reefs surrounded by water and affected by different climatic conditions and hydrodynamic conditions in all directions, and provide accurate data support for island reef embankment projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a flow chart of a method for determining the advance and retreat distance of a coral island reef beach sand boundary provided by an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of discretizing a target boundary line into a point set provided by an embodiment of the present invention;

[0025] Figure 3 is a schematic diagram of drawing a perpendicular line from a target point set to a baseline provided by an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of a minimum rectangular bounding box for constructing a target point provided by an embodiment of the present invention;

[0027] Figure 5 is a schematic diagram of determining the intersection of rectangular frames using a fast exclusion method provided by an embodiment of the present invention;

[0028] Figure 6 It is a schematic diagram of an equal-angle interval grouping centered on a centroid point provided by an embodiment of the present invention;

[0029] Figure 7 is a schematic diagram of the azimuth angle of a target point relative to a centroid point provided by an embodiment of the present invention;

[0030] Figure 8 It is a flow chart of a method for selecting a site for a coral island and reef levee project provided by an embodiment of the present invention;

[0031] Fig. 9 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Figure 1 The flowchart of a method for determining the distance of coral island reef beach sand boundary provided by an embodiment of the present invention is applicable to the case of omnidirectional measurement of circular or elliptical island reef boundary changes, and is executed by an electronic device. Figure 1 As shown, the method specifically includes:

[0036] S110. Obtain the beach sand boundary lines of coral islands and reefs in two periods, and use the beach sand boundary line of the earlier period as the baseline and the beach sand boundary line of the other period as the target boundary line.

[0037] Optionally, for a coral island reef, high-resolution remote sensing images of two periods are used to extract the boundary line of the coral island reef beach sand by using methods such as threshold segmentation, normalized water index or visual interpretation, and obtain the two-period data of the coral island reef beach sand boundary line, such as the beach sand boundary line data of 2019-5-18 and 2021-4-25. Then, the coral island reef beach sand boundary line data of the earlier period (such as 2019-5-18) is selected as the baseline, and the coral island reef beach sand boundary line data of the more recent period (such as 2021-4-25) is selected as the target boundary line.

[0038] S120, calculating the shortest distance from each target point on the target boundary line to the baseline, wherein if the target point is located in the closed area surrounded by the baseline, the shortest distance is positive, representing the erosion distance; if the target point is located outside the closed area surrounded by the baseline, the shortest distance is negative, representing the siltation distance.

[0039] Optionally, the target boundary line is first discretized into a point set. The method is to start from the starting point of the target boundary line, take a point at a certain distance on the boundary line, and obtain the target point set. Figure 2 In this embodiment, the spacing distance is set to 0.5 meters.

[0040] Then, the shortest distance from each target point in the target point set to the baseline is calculated in turn. The method is to generate a perpendicular line from each target point to the baseline, such as Figure 3 In a specific embodiment, for any target point, the process may include the following steps:

[0041] Step 1: Construct a minimum rectangular bounding box of the target point. The minimum rectangular bounding box is used to constrain the initial range of the shortest distance from the target point to the baseline. Optionally, the target point is recorded as P(x, y). Assuming that the length and width of the rectangular bounding box are both 2d, the minimum coordinate point P is calculated by min (xd,yd) and the maximum coordinate point P max (x+d,y+d) can construct the minimum rectangular bounding box of the target point, such as Figure 4 As shown. Preferably, the length and half of the width d of the rectangular enclosing frame are both 50 meters. Optionally, the length can also be determined based on the statistical dimensions of multiple coral islands and reefs. Usually, the diameter of an island or reef in all directions is several hundred meters, and the minimum value d of the diameter of a coral island or reef in all directions can be obtained from the statistical data. min ; then take the value less than A certain value is used as the length and width of the minimum rectangular bounding box for constructing any target point. The length can avoid covering the baseline on the side farther from the target point while maintaining an appropriate coverage range under the premise that the minimum rectangular bounding box can cover the baseline on the side closer to the target point.

[0042] Step 2: Divide the baseline into multiple line segments and construct the minimum rectangular bounding box of each line segment. Optionally, divide the baseline into multiple line segments in the order of coordinate points, such as Figure 5 As shown in the figure, the baseline segment formed by sequentially connecting 9 coordinate points is divided into line segments C1, C2, C3, C4, C5, C6, C7, and C8. Then, a line segment is taken out in turn, and a rectangular bounding box is constructed with any line segment as a diagonal line as the minimum rectangular bounding box of the line segment. For the convenience of distinction and description, in this embodiment, the minimum matrix bounding box of the target point constructed in step 1 is called the first minimum rectangular bounding box, and the minimum rectangular bounding box of the baseline line segment constructed in this step is called the second minimum rectangular bounding box.

[0043] Step 3: Use the fast exclusion method to determine whether the first minimum rectangular bounding box intersects with each second minimum rectangular bounding box. If they do not intersect, the foot of the perpendicular from the target point to the corresponding line segment must not be on the line segment, and the operation on the current line segment (current second minimum rectangular bounding box) is completed. If they intersect, continue to step 4.

[0044] Step 4. Determine the closest distance from the target point to the baseline based on each intersecting second minimum rectangular bounding box. Optionally, for any intersecting second minimum rectangular bounding box, first, calculate the foot of the perpendicular from the target point to the line segment corresponding to the second minimum rectangular bounding box; if the foot of the perpendicular is on the line segment, then the distance from the target point to the foot of the perpendicular is the closest distance from the target point to the line segment; if the foot of the perpendicular is on the extension line of the line segment, continue to calculate the distance from the target point to the two end points of the line segment, and take the minimum of the two distances as the closest distance from the target point to the line segment. After performing the above operations on each intersecting second minimum rectangular bounding box, the closest distance from the target point to each corresponding line segment can be obtained. By taking the minimum value from these closest distances, the closest distance from the target point to the baseline can be obtained. Exemplarily, in combination Figure 5 , the first minimum rectangular bounding box of the target point P intersects with the second minimum rectangular bounding boxes of the line segments C5 and C6 respectively. The closest distances from the target point P to the line segments C5 and C6 need to be calculated respectively. The minimum value of the two closest distances is the closest distance from the target point P to the baseline.

[0045] Step 5: If the target point is outside the closed area surrounded by the baseline, the closest distance to the target is set to a negative value. The closest distances obtained by steps 1 to 4 are all positive values, and it is impossible to distinguish between the erosion distance and the siltation distance. Therefore, this step uses a commonly used point-surface inclusion algorithm to determine whether each target point in the target point set is located within the polygon surrounded by the baseline. If it is outside the polygon, the closest distance from the target point to the baseline is set to a negative value.

[0046] S130, taking the centroid of the closed area enclosed by the target boundary line as the azimuth reference point, dividing the full angular range into multiple intervals; and averaging the closest distances of all target points in each interval to obtain the advance and retreat distances of the coral islands and reefs along the main directions of each interval, wherein each advance and retreat distance is used to provide a basis for site selection for island and reef embankment projects.

[0047] In order to achieve omnidirectional measurement of changes in island and reef boundaries, this embodiment divides the target point set into several groups at equal angle intervals, and estimates the advance and retreat distance of the island and reef boundary line for each group.

[0048] In a specific implementation, first, the centroid of the closed area enclosed by the target boundary line is calculated; and the centroid is used as a reference point, and the due east direction is taken as the 0° azimuth; starting from the 0° azimuth, rays are drawn outward at regular intervals in a counterclockwise direction, and the 360° full-range angle range is divided into multiple intervals by each ray, such as Figure 6 Preferably, the interval angle is 30°. At the same time, the center angle of each area can be selected as the representative of each area, which is called the main direction in this embodiment.

[0049] Then, calculate the group (i.e. interval) to which each target point in the target point set belongs. Figure 7 As shown, taking the calculation of the group to which the target point P belongs as an example, the azimuth of point P can be calculated based on the coordinates of the centroid point O and point P; substituting the azimuth into the following formula, the group to which point P belongs can be calculated:

[0050]

[0051] Wherein, θ represents the azimuth of point P relative to the centroid point O, Δδ represents the equal angle interval of the rays in the above group (for example, 30°), Indicates rounding up. The azimuth angle ranges from 0° to 360°, n is the index of the group, and the range is from 1 to N, where N represents the total number of groups.

[0052] Finally, for each group, the average forward or backward distance of all target points in the group is calculated. The calculation formula is as follows:

[0053]

[0054] Among them, D n represents the advance or retreat distance of the nth group. When it is a positive value, it represents the erosion distance, and when it is a negative value, it represents the siltation distance. k represents the total number of target points in the nth group. d i Represents the distance from each target point to the baseline in the nth group.

[0055] Furthermore, in response to the measurement operation of the advance and retreat distance of the coral reef boundary along a specific azimuth α, the interval to which α belongs can be determined first. Optionally, if (i-1)×Δδ≤α<i×Δδ, then α belongs to the interval with sequence number i; then, the average value D of the advance and retreat distance corresponding to the interval is calculated. i , as the distance of advance and retreat along the azimuth, so as to accurately and finely tell the user the distance of erosion or siltation of the beach sand boundary line of the coral island reef in a certain azimuth direction. This operation is very important in the site selection of island reef embankment projects, or the regulation and restoration of island reef beaches. For example, before the construction of the project, the user can pre-measure the boundary changes at a certain intended angle, and predict the engineering construction and governance effects based on this situation to determine the final engineering plan.

[0056] In summary, this embodiment provides a method for determining the distance of advance and retreat of coral island reef beach sand boundary. This method directly constructs an orthogonal section for the original coral island reef beach sand boundary line, can accurately determine the distance of advance and retreat of the current boundary line relative to the early boundary line, and measures the distance of advance and retreat according to different azimuth angles. It can also accurately measure the distance of advance and retreat of coral island reefs in a certain direction according to the azimuth angle input by the user. This embodiment overcomes the problems that the existing section method needs to introduce a virtual baseline, and the unreasonable setting of the virtual baseline will lead to large errors in the calculated coastline change distance; it also overcomes the problems of complex calculations and large amount of calculations caused by the rotation and segmentation of the coordinate system according to the direction of the coastline; it can quickly and accurately calculate the distance of siltation or retreat in all directions based on the characteristics of islands and reefs surrounded by water and affected by different climatic conditions and hydrodynamic conditions in all directions, and provide accurate data support for island reef embankment projects.

[0057] Figure 8 : is a flow chart of a method for selecting a coral island and reef embankment project site provided by an embodiment of the present invention. Figure 8 As shown, the method specifically includes:

[0058] S210. Using the method for determining the advance and retreat distance of the coral island and reef beach sand boundary described in any of the above embodiments, the advance and retreat distance of the coral island and reef along the main direction of each interval is obtained.

[0059] S220: If the advance and retreat distance along the main direction of an interval is positive and greater than a relevant threshold, determine the construction location of the embankment project according to the interval and / or the main direction.

[0060] If the advance and retreat distance in a certain interval or in a certain main direction is positive, it means that the boundary line has retreated in this direction. If the retreat distance is greater than the relevant threshold, such as exceeding the relevant standards for remediation and restoration, it indicates that the degree of erosion of the islands and reefs along this direction is relatively serious, and embankment projects need to be built to prevent the island and reef area from further shrinking. Optionally, the ray range corresponding to the interval can be used as the main protection area, and the construction scope of the embankment project can be determined around the area, such as building an embankment project within the area, or building an embankment project in a larger area centered on the area (which can exceed the area); at the same time, the direction of the embankment project can also be determined according to the main direction of the area, such as making the direction of the embankment project perpendicular to the main direction of the area, so as to block the erosion of the beach sand to the greatest extent, improve the defense effect of the embankment project and the direction of the remediation and restoration of the island and reef beaches, and avoid the cost waste caused by blind construction.

[0061] In summary, this embodiment determines the location where the island and reef levee project needs to be built according to the distance of silting or erosion in all directions of the coral islands and reefs, thereby improving the pertinence and scientific nature of the site selection of the levee project and reducing the construction cost. It should be noted that the coral island and reef levee project site selection method of this embodiment and the coral island and reef beach sand boundary advance and retreat distance determination method described in any of the above embodiments are based on the same inventive concept; any steps or limitations in the coral island and reef beach sand boundary advance and retreat distance determination method described in any of the above embodiments can be applied to this embodiment and achieve the same technical effect.

[0062] Fig. 9 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention is shown in FIG. Fig. 9 As shown, the device includes a processor 60, a memory 61, an input device 62 and an output device 63; the number of processors 60 in the device can be one or more. Fig. 9 A processor 60 is taken as an example; the processor 60, the memory 61, the input device 62 and the output device 63 in the device can be connected by a bus or other means. Fig. 9 The example of connecting through bus is taken in the following.

[0063] The memory 61, as a computer-readable storage medium, can be used to store software programs, computer executable programs and modules, such as the method for determining the distance between the advance and retreat of the coral island and reef beach sand boundary or the method for selecting the site for the coral island and reef dike project in the embodiment of the present invention. The processor 60 executes various functional applications and data processing of the device by running the software programs, instructions and modules stored in the memory 61, that is, to implement the above-mentioned method for determining the distance between the advance and retreat of the coral island and reef beach sand boundary or the method for selecting the site for the coral island and reef dike project.

[0064] The memory 61 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system and at least one application required for a function; the data storage area may store data created according to the use of the terminal, etc. In addition, the memory 61 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some instances, the memory 61 may further include a memory remotely arranged relative to the processor 60, and these remote memories may be connected to the device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0065] The input device 62 may be used to receive input digital or character information and generate key signal input related to user settings and function control of the device. The output device 63 may include a display device such as a display screen.

[0066] An embodiment of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining the advance and retreat distance of the coral island beach sand boundary, or the method for selecting a site for a coral island embankment project, as described in any embodiment.

[0067] The computer storage medium of the embodiment of the present invention can adopt any combination of one or more computer-readable media. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium can be, for example, but not limited to, a system, device or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program, which can be used by an instruction execution system, a device or a device or used in combination with it.

[0068] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0069] The program code embodied on the computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0070] Computer program code for performing the operations of the present invention may be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as C or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, as a separate software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the distance of advance and retreat of coral island reef beach sand boundary, characterized in that: include: Obtain the beach and sand boundary lines of coral islands and reefs in two periods, and use the beach and sand boundary line of the earlier period as the baseline and the beach and sand boundary line of the other period as the target boundary line; Calculate the shortest distance from each target point on the target boundary line to the baseline, wherein if the target point is located within the closed area surrounded by the baseline, the shortest distance is positive, representing the erosion distance; if the target point is located outside the closed area surrounded by the baseline, the shortest distance is negative, representing the siltation distance; specifically, construct a first minimum rectangular bounding box for any target point, the first minimum rectangular bounding box is used to constrain the preliminary range of the shortest distance from the target point to the baseline; divide the baseline into multiple line segments, and construct a second minimum rectangular bounding box for each line segment; use a fast exclusion method to determine whether the first minimum rectangular bounding box intersects with each second minimum rectangular bounding box; determine the shortest distance from the target point to the baseline based on each intersecting second minimum rectangular bounding box; The centroid of the closed area enclosed by the target boundary line is used as the azimuth reference point, and the full angular range is divided into multiple intervals; and based on the shortest distance of all target points in each interval, the advance and retreat distance of the coral islands and reefs along the main direction of each interval is calculated, wherein each advance and retreat distance is used to provide a basis for the site selection of the island reef embankment project.

2. The method according to claim 1, characterized in that: The step of constructing a first minimum rectangular bounding box of any target point includes: According to the statistical sizes of multiple coral reefs, determine the minimum diameter d of the coral reefs along multiple directions. min ; Determine less than A value of is used as the length and width of the first minimum rectangular bounding box for constructing any target point.

3. The method according to claim 1, characterized in that The step of constructing a second minimum rectangular bounding box for each line segment includes: A rectangular bounding box is constructed with any line segment as a diagonal line as the second minimum rectangular bounding box of the line segment.

4. The method according to claim 1, characterized in that: The determining, based on each intersecting second minimum rectangular bounding box, the shortest distance from the target point to the baseline comprises: S1, calculating the foot of the perpendicular from the target point to any line segment corresponding to the second intersecting minimum rectangular bounding box; S2. If the foot of the perpendicular is located on the line segment, determine that the distance from the target point to the foot of the perpendicular is the shortest distance from the target point to the line segment; S3. If the foot of the perpendicular is located on the extension line of the line segment, determine the minimum value of the distances from the target point to the two end points of the line segment as the shortest distance from the target point to the line segment; After performing the operations S1-S3 on each intersecting second minimum rectangular bounding box, the minimum value of the shortest distances from the target point to each corresponding line segment is taken as the shortest distance from the target point to the baseline.

5. The method according to claim 4, characterized in that The determining the shortest distance from the target point to the baseline according to each intersecting second minimum rectangular bounding box further includes: If the target point is outside the closed area surrounded by the baseline, the value of the closest distance to the target is taken as negative.

6. The method according to claim 1, characterized in that The centroid of the closed area surrounded by the target boundary line is used as the azimuth reference point, and the omnidirectional angle range is divided into multiple intervals, including: Taking the centroid of the closed area enclosed by the target boundary line; Taking the centroid as a reference point, the due east direction is taken as an azimuth of 0°; Starting from the 0° azimuth, rays are drawn outward at regular intervals in the counterclockwise direction, and each ray divides the 360° full angle range into multiple intervals.

7. A method for selecting a site for a coral island and reef embankment project, characterized in that: include: Adopting the method described in any one of claims 1 to 6, obtaining the advance and retreat distance of the coral island reef along the main direction of each interval; If the advance and retreat distance along the main direction of an interval is positive and greater than a relevant threshold, the construction position of the embankment project is determined according to the interval and / or the main direction.

8. An electronic device, characterized in that: include: one or more processors; a memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method for determining the advance and retreat distance of the coral island and reef beach sand boundary as described in any one of claims 1-6, or the method for selecting the site for the coral island and reef embankment project as described in claim 7.

9. A computer-readable storage medium, characterized in that: A computer program is stored thereon, which, when executed by a processor, implements the method for determining the advance and retreat distance of the coral island and reef beach sand boundary as described in any one of claims 1 to 6, or the method for selecting the site for a coral island and reef embankment project as described in claim 7.

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