Method, system and medium for automatic extraction of river width

Abstract

The present application relates to a method, system, and medium for automatically extracting river channel width. The method includes extracting target river channel and river island boundary data; performing linear interpolation and resampling of river channel boundaries; generating Voronoi polygons; filtering Voronoi polygons; generating the centerline of the river channel and extracting the boundary lines of each tributary; sorting the river channel centerline points according to the advancement path; resampling and smoothing the centerline using a spline smoothing algorithm; calculating the river channel cross section perpendicular to the river channel centerline; finding the intersection point between the cross section and the river channel boundary and the river island boundary; deriving the river channel width or river island width; and outputting the river channel width and cross section center point data. The present application can be applied to rivers of various shapes, achieving efficient and automatic extraction of high-resolution river channel width data, which is conducive to reducing the workload of manual measurement.

Description

Technical Field

[0001] The present application relates to the field of water conservancy remote sensing image information processing, and more specifically, to a method, system and medium for automatically extracting river channel width based on the Voronoi diagram method. Background Art

[0002] Channel width is one of the key criteria for determining flow patterns, sediment transport, and the type and density of riparian vegetation within a river system. For alluvial rivers in particular, channel width can change due to a range of natural processes, including the amount and duration of incoming water, the volume and size distribution of incoming sediment, the sediment composition of the riverbed and banks, and riparian vegetation. Analyzing the evolution of channel width is a valuable tool for understanding the impact of these factors on channel morphology. Extensive research has been conducted domestically and internationally on the relationship between channel width and changes in flow, sediment transport, and riparian vegetation. Furthermore, channel width influences energy exchange at the water-atmosphere interface and the biological habitats within river ecosystems, ultimately impacting riverbed morphology. Similarly, channel width influences infrastructure planning, such as the siting of bridges and dams. Therefore, channel width is a crucial indicator of river evolution.

[0003] Currently, existing river channel width measurement methods in academia and engineering are generally based on field measurements. However, field measurement methods require a significant investment of manpower and resources and are difficult to implement for large river basins or long, wide river sections. Additionally, some researchers have developed tools to automatically calculate river channel widths when available river boundary data is available. However, most of these algorithms are not suitable for complex river channel boundaries, such as those with islands or bifurcated channels. Therefore, a river channel width calculation method applicable to a variety of river channel morphologies is needed. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method, system and medium for automatic extraction of river channel width, which can be applicable to rivers of various shapes, increase the spatial resolution of river channel width extraction, and improve the extraction efficiency of river channel width data.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a method for automatically extracting river width, comprising the following specific steps:

[0007] S1. Determine the remote sensing image of the target river and extract the boundary data of the target river and river island;

[0008] S2. Import the target river channel and river island boundary data described in step S1 into MATLAB;

[0009] S3 smoothing the target river boundary data in step S2;

[0010] S4. performing linear interpolation and resampling of the river boundary after smoothing in step S3;

[0011] S5. Generate a Voronoi polygon based on the linear interpolation and the resampled boundary points in step S4;

[0012] S6. Filter the Voronoi polygons in step S5 to filter the Voronoi polygon endpoints that do not fall within the river boundary;

[0013] S7. Remove the Voronoi polygon endpoints with only one connection point to filter out invalid branch channels, and repeat this process until the number of remaining Voronoi polygon endpoints remains stable;

[0014] S8. Identify the endpoints of the Voronoi polygon with three connecting points, and repeat this process until the number of identified Voronoi polygon endpoints stabilizes;

[0015] S9. Backpropagating the points deleted in step S7, starting from the last endpoint with only one connection point, and advancing in reverse along the tributary path to obtain the reverse advancing point path;

[0016] S10. Back-calculate the points deleted in step S7, starting from the last point with only one connection point and moving forward along the tributary path, to obtain a forward-propelled point path until the nearest endpoint with three connection points is reached;

[0017] S11. Merge the forward and reverse propagation point paths to generate the centerline of the river channel and extract the boundary lines of each tributary;

[0018] S12. Sort the river centerline points according to the advancement path;

[0019] S13. Resample and smooth the centerline using a spline smoothing algorithm;

[0020] S14. Calculate the cross section of the river perpendicular to the centerline of the river;

[0021] S15. Find the intersection of the cross section with the river boundary and the river island boundary;

[0022] S16. Calculate the distance between the intersection points of a single cross section to obtain the width of the river channel or the width of the river island;

[0023] S17. Output the river width and cross-section center point data.

[0024] In step S12, the center lines are sorted based on the principle of the shortest distance.

[0025] In step 14, the cross section of the river channel perpendicular to the center line of the river channel is calculated, including but not limited to obtaining a perpendicular line by connecting two points before and after the calculation point.

[0026] In step S16, the distance between the intersection points of a single cross section is calculated to obtain the river width or the width of the river island. Specifically, the distance between the intersection point of the cross section and the river channel boundary is first calculated, and then the distance between the intersection point of the cross section and the river island boundary is calculated. The difference between the two distances is the river width.

[0027] In a second aspect, an embodiment of the present application provides a system for automatically extracting river channel width, the system comprising: a memory and a processor, the memory comprising a program for an automatic river channel width extraction method, wherein the program for the automatic river channel width extraction method, when executed by the processor, implements the following steps: determining a remote sensing image of a target river channel and extracting boundary data of the target river channel and river island; importing the boundary data of the target river channel and river island into MATLAB; smoothing the river channel boundary data; linearly interpolating and resampling the river channel boundary based on the smoothed river channel boundary; generating Voronoi polygons based on the linear interpolation and resampled boundary points; filtering the Voronoi polygons to filter out Voronoi polygon endpoints that do not fall within the river channel boundary; Remove the Voronoi polygon endpoints with only one connection point to filter out invalid branch rivers, and repeat this process until the number of remaining Voronoi polygon endpoints remains stable; identify the Voronoi polygon endpoints with three connection points, and repeat this process until the number of identified Voronoi polygon endpoints remains stable; reversely calculate the deleted points, starting from the last endpoint with only one connection point, and advance in the reverse direction along the tributary path to obtain the reverse-propelled point path; reversely calculate the deleted points, starting from the last point with only one connection point and advancing forward along the tributary path. , obtain the forward propulsion point path until it reaches the nearest endpoint with 3 connection points; merge the forward and reverse propulsion point paths to generate the centerline of the river and extract the boundary lines of each tributary; sort the river centerline points according to the propulsion path; use the spline smoothing algorithm to resample and smooth the centerline; calculate the river cross section perpendicular to the river centerline; find the intersection point of the cross section with the river boundary and the river island boundary; calculate the distance of a single cross section intersection point to obtain the river width or river island width; output the river width and cross section center point data.

[0028] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores program code, and when the program code is executed by a processor, the steps of the automatic river width extraction method as described above are implemented.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] Based on the known river channel boundaries and river island boundaries, the river centerline is first calculated in the absence of a river island. This can prevent the existence of a river island from interfering with the calculation of the river centerline and even preventing the generation of the river centerline. This effectively avoids the disadvantages of traditional automatic river channel width extraction methods, is applicable to rivers of various morphologies, and can achieve efficient and automatic extraction of high-resolution river channel width data, which is beneficial to engineering applications and related research. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 This is a schematic diagram of the river boundary and the river island boundary;

[0033] Figure 2 This is a schematic diagram of river boundary resampling;

[0034] Figure 3 To generate a Voronoi polygon diagram;

[0035] Figure 4 Delete the schematic diagram for the Voronoi polygon endpoints outside the river channel boundary;

[0036] Figure 5 Schematic diagram of the river center point.

[0037] Figure 6 To generate a schematic diagram of the river centerline;

[0038] Figure 7 This is a schematic diagram of the smoothing process of the river centerline;

[0039] Figure 8 To generate cross sections and calculate river width diagrams;

[0040] Figure 9 This is a flow chart of the method of this application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described below in conjunction with the accompanying drawings. It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0042] The terms "comprises," "comprising," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0043] The terms "first," "second," etc. are only used to distinguish one entity or operation from another entity or operation, and are not to be understood as indicating or implying relative importance, nor are they to be understood as requiring or implying any actual relationship or order between these entities or operations.

[0044] like Figure 9 As shown, an embodiment of the present invention provides a method for automatically extracting river channel width based on the Voronoi diagram method, comprising the following steps:

[0045] (1) Select a river boundary data containing a river island and import it into MATLAB, such as Figure 1 As shown;

[0046] (2) Remove the island boundary and resample and smooth the river channel boundary, such as Figure 2 As shown;

[0047] (3) Create Voronoi polygons based on the boundary points in MATLAB, such as Figure 3 As shown;

[0048] (4) Delete the endpoints of the Voronoi polygon outside the river boundary, such as Figure 4 As shown;

[0049] (5) Filter the Voronoi polygon endpoints that do not belong to the river centerline and only retain the river centerline points, such as Figure 5 As shown;

[0050] (6) Use the sorting algorithm to find the appropriate sorting of the remaining river centerline points and generate the river centerline, such as Figure 6 As shown;

[0051] (7) The centerline of the river channel is smoothed based on the Gaussian weighted moving average filtering algorithm and resampled according to the set interval, such as Figure 7 As shown;

[0052] (8) Generate a cross section perpendicular to the centerline based on the points on the centerline of the river, find the intersection with the river boundary line and the river island boundary line, and output the final river width and river island width data, such as Figure 8 shown.

[0053] An embodiment of the present application provides a system for automatically extracting river channel width based on a Voronoi diagram method. The system includes: a memory and a processor, wherein the memory includes a program for automatically extracting river channel width based on a Voronoi diagram method. When the program is executed by the processor, the system implements the following steps: determining a remote sensing image of a target river channel and extracting boundary data of the target river channel and river island; importing the boundary data of the target river channel and river island into MATLAB; smoothing the river channel boundary data; linearly interpolating and resampling the river channel boundary based on the smoothed river channel boundary; generating Voronoi polygons based on the boundary points obtained by the linear interpolation and resampling; filtering the Voronoi polygons to filter out Voronoi polygon endpoints that do not fall within the river channel boundary; Remove the Voronoi polygon endpoints with only one connection point to filter out invalid branch rivers, and repeat this process until the number of remaining Voronoi polygon endpoints remains stable; identify the Voronoi polygon endpoints with three connection points, and repeat this process until the number of identified Voronoi polygon endpoints remains stable; reversely calculate the deleted points, starting from the last endpoint with only one connection point, and advance in the reverse direction along the tributary path to obtain the reverse-propelled point path; reversely calculate the deleted points, starting from the last point with only one connection point and advancing forward along the tributary path. , obtain the forward propulsion point path until it reaches the nearest endpoint with 3 connection points; merge the forward and reverse propulsion point paths to generate the centerline of the river and extract the boundary lines of each tributary; sort the river centerline points according to the propulsion path; use the spline smoothing algorithm to resample and smooth the centerline; calculate the river cross section perpendicular to the river centerline; find the intersection point of the cross section with the river boundary and the river island boundary; calculate the distance of a single cross section intersection point to obtain the river width or river island width; output the river width and cross section center point data.

[0054] An embodiment of the present application provides a computer-readable storage medium storing program code. When the program code is executed by a processor, the steps of the method for automatically extracting river width based on the Voronoi diagram method as described above are implemented.

[0055] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0056] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0059] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0060] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0061] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can be implemented using any method or technology to store information. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change RAM (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory computer-readable media such as modulated data signals and carrier waves.

[0062] The above description is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for automatically extracting river width, characterized in that: The specific steps include: S1. Determine the remote sensing image of the target river and extract the boundary data of the target river and river island; S2. Import the target river channel and river island boundary data described in step S1 into MATLAB; S3 smoothing the target river boundary data in step S2; S4. performing linear interpolation and resampling of the river boundary after smoothing in step S3; S5. Generate a Voronoi polygon based on the linear interpolation and the resampled boundary points in step S4; S6. Filter the Voronoi polygons in step S5 to filter the Voronoi polygon endpoints that do not fall within the river boundary; S7. Remove the Voronoi polygon endpoints with only one connection point to filter out invalid branch channels, and repeat this process until the number of remaining Voronoi polygon endpoints remains stable; S8. Identify the endpoints of the Voronoi polygon with three connecting points, and repeat this process until the number of identified Voronoi polygon endpoints stabilizes; S9. Backpropagating the points deleted in step S7, starting from the last endpoint with only one connection point, and advancing in reverse along the tributary path to obtain the reverse advancing point path; S10. Back-calculate the points deleted in step S7, starting from the last point with only one connection point and moving forward along the tributary path, to obtain a forward-propelled point path until the nearest endpoint with three connection points is reached; S11. Merge the forward and reverse propagation point paths to generate the centerline of the river channel and extract the boundary lines of each tributary; S12. Sort the river centerline points according to the advancement path; S13. Resample and smooth the centerline using a spline smoothing algorithm; S14. Calculate the cross section of the river perpendicular to the centerline of the river; S15. Find the intersection of the cross section with the river boundary and the river island boundary; S16. Calculate the distance between the intersection points of a single cross section to obtain the width of the river channel or the width of the river island; S17. Output the river width and cross-section center point data.

2. The method for automatically extracting river width according to claim 1, characterized in that: In step S12, the center lines are sorted based on the principle of the shortest distance.

3. The method for automatically extracting river width according to claim 1, characterized in that: In step 14, the cross section of the river perpendicular to the centerline of the river is calculated, including the perpendicular line obtained by connecting the two points before and after the calculation point.

4. The method for automatically extracting river width according to claim 1, characterized in that: In step S16, the distance between the intersection points of a single cross section is calculated to obtain the river width or the width of the river island. Specifically, the distance between the intersection point of the cross section and the river channel boundary is first calculated, and then the distance between the intersection point of the cross section and the river island boundary is calculated. The difference between the two distances is the river width.

5. A river width automatic extraction system, characterized in that: The system includes: a memory and a processor, wherein the memory includes a program for an automatic river channel width extraction method, and when the program is executed by the processor, the following steps are implemented: determining a remote sensing image of a target river channel, extracting boundary data of the target river channel and river island; importing the boundary data of the target river channel and river island into MATLAB; smoothing the river channel boundary data; linearly interpolating and resampling the river channel boundary based on the smoothed river channel boundary; generating Voronoi polygons based on the linear interpolation and resampled boundary points; filtering the Voronoi polygons to filter out Voronoi polygon endpoints that do not fall within the river channel boundary; Remove the Voronoi polygon endpoints with only one connection point to filter out invalid branch rivers, and repeat this process until the number of remaining Voronoi polygon endpoints remains stable; identify the Voronoi polygon endpoints with three connection points, and repeat this process until the number of identified Voronoi polygon endpoints remains stable; reversely calculate the deleted points, starting from the last endpoint with only one connection point, and advance in the reverse direction along the tributary path to obtain the reverse-propelled point path; reversely calculate the deleted points, starting from the last point with only one connection point and advancing forward along the tributary path. , obtain the forward propulsion point path until it reaches the nearest endpoint with 3 connection points; merge the forward and reverse propulsion point paths to generate the centerline of the river and extract the boundary lines of each tributary; sort the river centerline points according to the propulsion path; use the spline smoothing algorithm to resample and smooth the centerline; calculate the river cross section perpendicular to the river centerline; find the intersection point of the cross section with the river boundary and the river island boundary; calculate the distance of a single cross section intersection point to obtain the river width or river island width; output the river width and cross section center point data.

6. A computer-readable storage medium, characterized in that The computer-readable storage medium stores program code, and when the program code is executed by a processor, the steps of the method for automatically extracting river width according to any one of claims 1 to 4 are implemented.

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