A method, device, equipment, medium and product for flow field cell division and confluence link identification for characterizing three-dimensional terrain and water system extraction

Abstract

The present invention discloses a flow field cell division and confluence link identification method, device, equipment, medium and product for characterizing three-dimensional terrain and water system extraction, which relates to the field of terrain analysis. The method includes: performing B-spline processing and equally spaced point interpolation on the contour lines of the watershed area; taking the equally spaced elevation points on the contour lines of the watershed area as the center, using Thiessen polygons to divide irregular flow field cells to obtain a Voronoi diagram; classifying and analyzing the flow field cells in the Voronoi diagram to obtain the edge line category of the flow field cells; performing confluence analysis on the flow field cells according to the edge line category of the flow field cells to determine the category of the flow field cells; performing water flow field demonstration on the Voronoi diagram according to the category of the flow field cells, and extracting the water system river network of the watershed area. The flow field cells and flow chains obtained by the present invention can better characterize the three-dimensional terrain, display the flood process and the water system river network based on the water flow field, and realize the accurate extraction of the water system river network.

Description

Technical Field

[0001] The present invention relates to the technical field of digital terrain analysis, and in particular to a flow field cell division and confluence link identification method, device, equipment, medium and product for characterizing three-dimensional terrain and extracting water systems. Background Art

[0002] In the process of constructing a distributed hydrological model of a watershed and simulating the rainfall-runoff process with the help of the constructed model, determining the river network that represents the surface runoff link is a necessary step and key link in modeling. Although there are many methods for dividing the calculation unit and determining the flow direction based on raster DEM, the calculation units and water flow directions divided based on the existing methods still have large deviations from the actual physical process. How to accurately depict the surface runoff link in a watershed with complex and undulating terrain is a technical challenge for hydrological numerical simulation.

[0003] Determining the direction of surface runoff is the basis for dividing the boundaries of sub-catchment areas, river networks, and upstream and downstream link relationships. Traditional multi-directional flow algorithms based on raster DEM (such as the D8 algorithm) use the raster as a point source of runoff, which can describe the spatial distribution of hydrological characteristics and derive water flow diffusion patterns on divergent slopes, but what is obtained in the flat area at the bottom of the valley is a woven river network that does not conform to reality. In addition, when traditional algorithms are applied to catchments with multiple types of terrain such as divergence, convergence, depressions, and flatness, the surface runoff link extraction results deviate significantly from the actual runoff links, making it difficult to meet the accuracy requirements of simulating rainstorm flood processes in catchments with complex undulating terrain in mountainous areas. Summary of the invention

[0004] The purpose of the present invention is to provide a flow field cell division and confluence link identification method, device, equipment, medium and product for characterizing three-dimensional terrain and water system extraction, which can realize the display and accurate extraction of water system river network.

[0005] To achieve the above object, the present invention provides the following solution.

[0006] In a first aspect, the present application provides a method for flow field cell division and confluence link identification for characterizing three-dimensional terrain and water system extraction, comprising the following steps.

[0007] The watershed contour lines are processed by B-spline and interpolated with equally spaced points to obtain equally spaced elevation points on the watershed contour lines;

[0008] Taking the elevation points evenly spaced on the contour lines of the catchment area as the center, the irregular flow field cells are divided using Thiessen polygons to obtain a Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain with flow direction and outflow distribution coefficients composed of Thiessen polygons, the cell chain includes a plurality of flow field cells, and the flow field cells are represented by Thiessen polygons;

[0009] Based on the plane potential flow theory, the flow field cells in the Voronoi diagram are classified and analyzed to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge;

[0010] According to the edge line category of each flow field cell, the flow field cell is subjected to confluence analysis to determine the category of each flow field cell; the category of the flow field cell is ridge boundary cell, slope cell, ridge divergence cell or valley bottom convergence cell;

[0011] The water flow field is demonstrated on the Voronoi diagram according to the category of each flow field cell, and the river network of the catchment area is extracted.

[0012] In a second aspect, the present application provides a flow field cell division and confluence link identification device for characterizing three-dimensional terrain and water system extraction, the device applies the above method, and the device includes:

[0013] The elevation point sampling module is used to perform B-spline processing and equally spaced point interpolation on the watershed contour lines to obtain equally spaced elevation points on the watershed contour lines;

[0014] A flow field cell division module is used to divide irregular flow field cells using Thiessen polygons with equally spaced elevation points on the contour lines of the catchment area as the center, and obtain a Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain with flow direction and outflow distribution coefficients composed of Thiessen polygons, the cell chain includes a plurality of flow field cells, and the flow field cells are represented by Thiessen polygons;

[0015] An edge category module is used to classify and analyze the flow field cells in the Voronoi diagram based on the plane potential flow theory to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge;

[0016] A flow field cell category recognition module is used to perform confluence analysis on the flow field cells according to the edge category of each flow field cell to determine the category of each flow field cell; the category of the flow field cell is a ridge boundary cell, a slope cell, a ridge divergent cell or a valley bottom convergent cell;

[0017] The river network extraction module is used to demonstrate the water flow field of the Voronoi diagram according to the category of each flow field cell and extract the river network of the catchment area.

[0018] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction.

[0019] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction.

[0020] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction.

[0021] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0022] The present invention discloses a flow field cell division and confluence link identification method, device, equipment, medium and product for characterizing three-dimensional terrain and water system extraction. The present application processes the B-spline of the watershed contour line and divides it equally; processes the contour line equally spaced points based on the plane potential flow theory and the Voronoi diagram to form the irregular flow field cell division of the terrain; classifies the flow field cells and conducts confluence analysis to form the flow field cell confluence link; assigns the flow direction, elevation and other attributes to obtain the three-dimensional irregular flow field cells of the terrain; extracts the river network and basin boundary of the water system from the flow field cells. The flow field cells and flow chain obtained in the present application can better characterize the three-dimensional terrain, display the flood process and extract the river network of the water system based on the water flow field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A flow chart of a flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction provided by the present invention.

[0025] Figure 2 This is a schematic diagram of contour line processing using the B-spline smoothing method provided by the present invention.

[0026] Figure 3 A schematic diagram of the present invention for numbering and resampling contour lines into equally spaced elevation points.

[0027] Figure 4 A schematic diagram of the Voronoi polygons of equally spaced elevation points of the B-spline contour provided by the present invention.

[0028] Figure 5 Schematic diagram of Voronoi polygons of special areas provided by the present invention.

[0029] Figure 6 A schematic diagram of a depression element in the edge classification provided by the present invention.

[0030] Figure 7 A schematic diagram of a ridge line edge connected to an upper outflow edge provided by the present invention.

[0031] Figure 8 A schematic diagram of the undetermined edge of the saddle-shaped region provided by the present invention.

[0032] Fig. 9 A schematic diagram of a depression element in the flow field cell classification provided by the present invention.

[0033] Fig.10 A schematic diagram of the overall results of cell classification provided by the present invention.

[0034] Fig.11 A schematic diagram of the structure of a computer device provided by the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide a flow field cell division and confluence link identification method, device, equipment, medium and product for characterizing three-dimensional terrain and water system extraction, so as to realize the display and accurate extraction of water system river network.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Exploring digital terrain hydrological analysis based on contour lines can comply with potential flow theory and easily handle runoff links in complex undulating terrain areas (divergence, convergence, depressions and flat areas interlaced). It is convenient to study the physical process of surface runoff in mountainous areas at higher spatial resolution (better than 10 meters) of slope units without prior terrain knowledge. It can make up for the shortcomings of traditional surface runoff direction analysis based on raster DEM and improve the calculation accuracy of rainfall runoff simulation in the catchment area.

[0039] Example 1

[0040] like Figure 1 As shown, Embodiment 1 of the present invention provides a flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction, and the method comprises the following steps:

[0041] Step 101, performing B-spline processing and equally spaced point interpolation on the watershed contour lines to obtain equally spaced elevation points on the watershed contour lines.

[0042] Given a grid DEM with a certain accuracy in a plane coordinate system, the B-spline smoothing method is used to extract contour lines with an elevation interval of Δz.

[0043] like Figure 2 As shown in the figure, the contour lines extracted by the B-spline smoothing method can avoid the jagged shape of ordinary contour lines. These jagged shapes can cause sudden changes in the normal direction of local contour lines, while B-spline smoothing can avoid these sudden changes and form a natural transition in the normal direction.

[0044] Contour lines are numbered and resampled to equally spaced elevation points, e.g. Figure 3 As shown. The contour lines are assigned unique ID numbers m in descending order of elevation, and each contour line is resampled into contour points with the same interval of Δz according to the curve distance, and each point is assigned a sequence number n in the order of adoption. In this way, each elevation point (m, n, x, y, z) contains plane position information x, y, elevation information z, elevation sequence information m and adjacent information n on the same line.

[0045] Step 102, taking the equally spaced elevation points on the contour lines of the catchment area as the center, using Thiessen polygons to divide the irregular flow field cells to obtain a Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain composed of Thiessen polygons with flow direction and outflow distribution coefficients, the cell chain includes multiple flow field cells, and the flow field cells are represented by Thiessen polygons.

[0046] Use these elevation points to construct the Delaunay triangulation and Voronoi diagram, such as Figure 4 shown.

[0047] For point n on line m, let its corresponding Voronoi polygon be V(P m,n ) (here called cells), decompose the Thiessen polygon into a series of edges, which can be divided into two categories: 1) intersecting with contour lines; 2) when not intersecting with contour lines, they are divided into upslope edges and downslope edges. Such cells, cell edges and cell vertices have the following characteristics:

[0048] 1) Characteristics of the edge lines that intersect the contour lines

[0049] Due to the characteristics of the Delaunay triangle, when the edge lines intersect the contour lines, they must be orthogonal. According to potential flow theory, the orthogonal edge lines represent the local streamlines of the flow field, such as Figure 4 As shown in A.

[0050] 2) Characteristics of edges that do not intersect contour lines

[0051] When Δz is small enough, the outflow edges of the cells on the same z0 contour line are almost all located on its two auxiliary contour lines z0±Δz / 2, such as Figure 4 As shown in B. Therefore, if the contour lines are assumed to be equipotential lines, the contour lines determine the flow field on the terrain surface, and the Voronoi polygons represent the flow field cells. Let the angle between the local streamline and its auxiliary contour line be β, the cumulative distribution and average value of β can be used to measure the approximation between the flow field cells represented by the Voronoi polygons and the real flow field.

[0052] 3) It can be assumed that the flow direction within the flow field cell is consistent: from the uphill edge to the downhill edge, such as Figure 4 As shown in A.

[0053] 4) Let the outflow in the cell be Q. According to the potential flow theory, when the equipotential lines intersect the cell as lines a and b, the outflow along a and b is proportional to their lengths. Since the local streamlines are almost orthogonal to the auxiliary contour lines, when the cell flows to the neighboring cells with shared edges downstream, the length of the downslope edge can be assumed to be the outflow distribution coefficient, as follows: Figure 4 As shown in C, that is:

[0054]

[0055] Where k is the number of downhill edges of flow field cell i; Q i is the total outflow of flow field cell i; Q i,j is the flow field cell i along the shared edge L j Outflow to flow field cell j.

[0056] 5) After decomposing the Thiessen polygons into polylines, each vertex is assigned an elevation value, and the original elevation point of the cell is connected to each of its vertices to form an internal triangulated network (TINs). This internal TINs has three uses: 1) It can be used to calculate the average slope of the cell; 2) It can be used to color the hydrological simulation results; 3) Three-dimensional polyline segments construct a consistent new 3D line drawing topographic map. Compared with traditional grid and triangulated network topographic maps, this 3D line drawing topographic map can not only reflect the elevation information, but also reflect the local flow field, and more finely characterize the changes in streamline curvature (convex, flat or concave) and contour curvature (divergent, parallel or convergent).

[0057] 6) In the plane area displayed by closed contour lines, Voronoi polygons give reasonable segmentation, such as Figure 5 As shown in A.

[0058] 7) In the divergent area near the ridge line, such as Figure 5 As shown in B in the figure, and the convergence area near the valley line, such as Figure 5 As shown in C, the space partitioning given by the Voronoi polygons is deterministic and optimal.

[0059] 8) For a suitable Δz value, the local streamlines can be considered to be orthogonal to their two auxiliary contour lines, so the shape of the flow field cell can be assumed to be a rectangle.

[0060] 9) The width of the flow field cell is Δz.

[0061] 10) The length of a flow field cell is calculated from its area and width.

[0062] 11) The slope of the flow field cell is calculated through its internal triangulated networks (TINs).

[0063] 12) The flow field cells form a complete flow field cell confluence calculation chain through the outflow distribution coefficient determined by the shared edge downstream, which is referred to as the flow field cell chain for short.

[0064] Step 103, classify and analyze the flow field cells in the Voronoi diagram based on the plane potential flow theory to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge.

[0065] The classification of edges and cells is to give them various specific performances and properties in the flow field. The classification of edges is based on the properties of its core point and the two adjacent points sharing the edge. The classification of edges and cells often needs to be done interactively. The following mark "B*)" refers to edge classification, and "C*)" refers to cell classification.

[0066] Let E1E2 be an edge of the Voronoi polygon of point P, and shared with the adjacent point P'. The classification rules of edge E1E2 are as follows:

[0067] B1) If P and P' originate from the same contour line and have adjacent sampling sequence numbers, then the streamline edge = [1].

[0068] After marking the "streamline edges", the cells where the streamline edges intersect and the intersection points are extracted to form two special data sets. The cells where the streamline edges intersect have special significance in the digitization of continuous flow fields. They reflect the divergence and convergence of the flow field. When the cells where the streamline edges intersect have outflow edges but no inflow edges, it is a sign of divergence at the terrain ridge line, and the intersection point is also the connection point of the ridge line; when the cells where the streamline edges intersect have inflow edges but no outflow edges, it is a sign of convergence at the bottom of the terrain, and the intersection point is also the connection point of the valley bottom watershed edge, such as Figure 6 shown.

[0069] B2) If the elevation of P is less than the elevation of P', then the upslope inflow edge = [2].

[0070] B3) If the elevation of P>the elevation of P', then the downslope outflow edge = [3].

[0071] B4) If P and P' are the same contour point and the sampling sequence numbers are not adjacent, the default is valley bottom catchment edge = [4].

[0072] B5) If P' is not within the catchment area, then the outer edge = [5].

[0073] B6) If P and P' are not points on the same contour line, and the elevation of P' = the elevation of P, then it is preset as a pending edge.

[0074] B7) If the streamline edges of P intersect, there is no inflow edge, but there is an outflow edge, then the [4] type edge connected to the intersection is reset to the ridge edge [5]; the [4] type edge connected to the ridge edge [5] is also reset to the ridge edge [7]. This rule can identify most ridges.

[0075] B8) If E1E2 of P is a [4] edge, the elevation of P is less than the elevation of P', and E1E2 is connected to the outflow edge of P', then E1E2 is reset to the ridge edge [5], that is, the [4] edge connected to the upper layer is actually the ridge edge [5]; all [4] edges connected to the ridge edge [5] are also reset to the ridge edge [5]. This rule is a supplement to rule B7, such as Figure 7 shown.

[0076] B9) The undetermined edge connected to the valley bottom watershed edge [4] is reset to the valley bottom watershed edge [4].

[0077] The remaining pending edges all appear in the saddle region, such as Figure 8 When a saddle area appears at the bottom of a valley, the cell containing the pending edge often has no outflow edge. In this case, the pending edge is reset to the valley bottom sink edge [4]. If the cell containing the pending edge has an outflow edge, the saddle area often appears at the top of a mountain, and the pending edge is reset to the ridge edge [5].

[0078] B10) If P has no outflow edge, no sink edge, and the streamlines do not cross, but contain pending edges, then its pending edges are reset to valley sink edges [4], and all the pending edges connected to it are also reset to valley sink edges [4]. This rule can solve the outflow destination of most flat ground cells without outflow.

[0079] Step 104, performing confluence analysis on the flow field cells according to the edge line category of each flow field cell to determine the category of each flow field cell; the category of the flow field cell is ridge boundary cell, slope cell, ridge divergence cell or valley bottom convergence cell.

[0080] The main purpose of classifying flow field cells is to determine the depression units with undetermined flow directions, which need to be connected to the catchment cells at the bottom of the valley and the slope cells with normal outflow, to pave the way for subsequent hydrological analysis.

[0081] C1) Depression element: If the original contour line is closed and all the flow field cells on it have no downslope outflow edge, it is defined as a depression; if the original contour line is closed and has a downslope outflow edge, but the depression element of the closed contour line with a smaller total length of all outflow contour lines is also a depression; on the same contour line, if both the left and right neighboring elements are depressions, the unit is also a depression, such as Fig. 9 shown.

[0082] C2) Slope element: a non-depression element with a downslope outflow edge is defined as a slope element.

[0083] C3) Catchment element: A non-depression or non-flat land element with an upslope inflow edge and no downslope outflow edge, but containing a valley bottom catchment edge or a streamline edge intersection, is defined as a convergent catchment element.

[0084] C4) Boundary element: A unit containing an external edge is defined as a boundary element.

[0085] The classification results based on the above steps are as follows Fig.10 shown. Fig.10 It is an area with complex terrain in the upper reaches of the Minjiang River Basin. Through the FFCC edge and cell classification, the catchment element and valley bottom catchment edge form a clear overall water system network.

[0086] Step 105, performing a water flow field demonstration on the Voronoi diagram according to the category of each flow field cell, and extracting the river network of the catchment area.

[0087] According to the specific embodiments provided in this application, this application discloses the following technical effects.

[0088] The Thiessen polygons of equally spaced interpolation points of B-spline contours are used as flow field cells for mountainous terrain, and the Thiessen polygons are decomposed into a series of edges and classified into local streamlines and outflow edges. The traditional idea of ​​continuous streamlines is abandoned and replaced by local streamlines. i The outflow edges of the cells on the contour lines are almost all located on their two auxiliary contour lines z i ±Δz / 2. Based on the potential flow theory, the length of these outflow edges is assumed to be the outflow distribution coefficient. Therefore, the Thiessen polygons form a cell chain with a clear flow direction and a determined outflow distribution coefficient. 2 The results show that the contour method is very easy to execute automatically, and there is no confusion about the flow direction of divergence, convergence, depression or flat area. This method can more objectively reflect the flow direction, flow length and slope of the slope. By coupling the numerical solution of kinematic waves based on the Aitkin iterative algorithm, this method can easily calculate the slope confluence.

[0089] Although terrain contours are similar to equipotential lines in physics, it is difficult to express them as mathematical functions to calculate streamlines or flow tubes. The Thiessen polygons of equally spaced interpolation points of B-spline contours are used as flow field cells in mountainous terrain. First, smooth contours with equal intervals of Δz are extracted from the raster DEM using B-spline. Smooth contours are used to avoid chaotic changes in local flow directions. Then, the contours are interpolated into elevation points with Δz as the interval. The consistent spacing in the two steps makes the three-dimensional shape of the cell close to a square. Finally, the Thiessen polygons of these elevation points are obtained. The Thiessen polygons are disassembled into a series of edges and classified into local streamlines and outflow edges. The outflow edges of cells on the same z0 contour are almost all located on their two auxiliary contours z0±Δz / 2. Based on the potential flow theory, the length of the outflow edge is assumed to be the outflow distribution coefficient (L i / ∑L n ).

[0090] In order to simulate hydrological processes based on slope cells, the shape, width, length and slope of the cell are the basic geometric parameters. 2The small watershed of is taken as a research case, and Δz is taken as 20m. Using the method of the present invention, it is divided into 5792 units. For a suitable Δz value, it can be considered that the local streamlines are orthogonal to their two auxiliary contour lines, and the shape of the cell is a rectangle. Assuming that the width of the cell is Δz, its length is calculated by its area and width. The smaller Δz is, the smaller the range of the length value is. The internal triangulation of the cell is constructed by the original contour point of a cell and its vertex, and the cell slope is calculated using this internal triangulation. When Δz is taken larger, the cumulative distribution curve of the unit slope shifts to the left and the average slope becomes smaller. The cell chain list is used to calculate the catchment area of ​​the cell, and all the basin units are traced back from one outlet cell. Within the basin unit, the cells that do not contain shared edges are classified as boundary cells, and connecting this unshared edge forms the basin boundary. Set a water system threshold, extract the water system cells, and connect the elevation points of the water system cells to form a water system.

[0091] In addition to the faces and edges of Thiessen polygons, vertex information is also very useful in FFCC models. After decomposing Thiessen polygons into polylines and assigning elevation values ​​to each point, it is possible to use this three-dimensional polyline to construct a 3D line drawing terrain map. On the one hand, Thiessen polygons become 3D line drawing terrain maps; on the other hand, they can be used to construct internal TINs and color hydrological simulation results. Compared with traditional grid and triangulated network terrain maps, this 3D line drawing terrain map can not only reflect elevation information, but also reflect the local flow field, and more finely characterize the changes in streamline curvature (convex, flat or concave) and contour curvature (divergent, parallel or convergent).

[0092] Using B-spline contours to interpolate equally spaced points to generate Thiessen polygons, disassembling Thiessen polygons into a series of edges and giving them hydrological characteristics can reasonably generalize the slope units in mountainous areas. The edges in the Thiessen polygons that do not intersect with the contour lines can represent the water cycle and surface process flow field determined by the contour lines. This contour-based method can avoid the flow direction and outflow distribution coefficient problems of the raster DEM method.

[0093] Example 2

[0094] The embodiment provides a flow field cell division and confluence link identification device for characterizing three-dimensional terrain and water system extraction, the device applies the method of embodiment 1, and the device includes:

[0095] The elevation point sampling module is used to perform B-spline processing and equally spaced point interpolation on the watershed contour lines to obtain equally spaced elevation points on the watershed contour lines.

[0096] The flow field cell division module is used to divide irregular flow field cells using Thiessen polygons with equally spaced elevation points on the contour lines of the catchment area as the center to obtain the Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain with flow direction and outflow distribution coefficients composed of Thiessen polygons, the cell chain includes multiple flow field cells, and the flow field cells are represented by Thiessen polygons.

[0097] The edge category module is used to classify and analyze the flow field cells in the Voronoi diagram based on the plane potential flow theory to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge.

[0098] The flow field cell category recognition module is used to perform confluence analysis on the flow field cells according to the edge category of each flow field cell to determine the category of each flow field cell; the category of the flow field cell is ridge boundary cell, slope cell, ridge divergence cell or valley bottom convergence cell.

[0099] The river network extraction module is used to demonstrate the water flow field of the Voronoi diagram according to the category of each flow field cell and extract the river network of the catchment area.

[0100] Example 3

[0101] This embodiment provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction of Embodiment 1.

[0102] like Fig.11 As shown, the computer device can be a database. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store pending transactions. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction in Example 1 are implemented.

[0103] Example 4

[0104] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction of Embodiment 1 is implemented.

[0105] Example 5

[0106] This embodiment provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction.

[0107] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided by the present invention may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited thereto. The processor involved in each embodiment provided by the present invention may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a data processing logic of a programmable logic device, etc., but are not limited thereto.

[0108] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction, characterized in that: The method comprises the following steps: The watershed contour lines are processed by B-spline and interpolated with equally spaced points to obtain equally spaced elevation points on the watershed contour lines; Taking the elevation points evenly spaced on the contour lines of the catchment area as the center, the irregular flow field cells are divided using Thiessen polygons to obtain a Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain with flow direction and outflow distribution coefficients composed of Thiessen polygons, the cell chain includes a plurality of flow field cells, and the flow field cells are represented by Thiessen polygons; Based on the plane potential flow theory, the flow field cells in the Voronoi diagram are classified and analyzed to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge; According to the edge line category of each flow field cell, the flow field cell is subjected to confluence analysis to determine the category of each flow field cell; The types of flow field cells are ridge boundary cells, slope cells, ridge divergent cells, or valley bottom converging cells; According to the category of each flow field cell, the Voronoi diagram is used to demonstrate the water flow field and extract the river network of the catchment area; The watershed contour lines are processed by B-spline and interpolated with equally spaced points to obtain equally spaced elevation points on the watershed contour lines, including: Perform B-spline smoothing on the watershed contours to obtain the contours after B-spline smoothing; The contour lines after B-spline smoothing are divided into equally spaced segments to obtain equally spaced elevation points (m, n, x, y, z) on the contour lines of the catchment area; where m represents the order information of the contour lines, n represents the order information of the elevation points on the same contour line after B-spline smoothing, x and y represent the plane position information, and z represents the elevation information; Taking the equally spaced elevation points on the contour lines of the catchment area as the center, the irregular flow field cells are divided using Thiessen polygons to obtain the Voronoi diagram of the catchment area, which includes: Construct a Voronoi diagram based on the equally spaced elevation points on the watershed contour line; the Voronoi diagram includes a plurality of Thiessen polygons; there is a common edge between adjacent Thiessen polygons; there is no overlapping relationship between each Thiessen polygon; a Thiessen polygon surrounds an elevation point on the watershed contour line; Determine the flow direction of each Thiessen polygon according to the elevation information of the elevation points surrounded by the adjacent Thiessen polygons of each Thiessen polygon; Based on the flow direction of each Thiessen polygon, the outflow distribution coefficient is calculated; According to the flow direction and outflow distribution coefficient of each Thiessen polygon, a cell chain with flow direction and outflow distribution coefficient is formed on the Voronoi diagram; Based on the plane potential flow theory, the flow field cells in the Voronoi diagram are classified and analyzed to obtain the edge line category of each flow field cell, which specifically includes: Let i=1, 2, ..., I respectively; wherein I is the number of edges of the target flow field cell; the target flow field cell is any flow field cell in the Voronoi diagram; Determine whether there is another flow field cell in the Voronoi diagram that contains the i-th edge of the target flow field cell, and obtain a first determination result; If the first judgment result is no, determining the i-th edge of the target flow field cell as a boundary edge; If the first judgment result is yes, another flow field cell including the i-th edge of the target flow field cell is taken as an adjacent flow field cell, and it is judged whether the elevation point in the adjacent flow field cell and the elevation point in the target flow field cell are on the same contour line to obtain a second judgment result; If the second judgment result is yes, then judging whether the elevation point in the adjacent flow field cell is adjacent to the elevation point of the target flow field cell, and obtaining a third judgment result; If the third judgment result is yes, then the i-th edge of the target flow field cell is determined to be a streamline edge; if the third judgment result is no, then the i-th edge of the target flow field cell is determined to be a valley sink edge or a ridge edge; If the second judgment result is no, then judging whether the elevation point in the target flow field cell is higher than the elevation point in the adjacent flow field cell, and obtaining a fourth judgment result; If the fourth judgment result is yes, determining that the i-th edge of the target flow field cell is a downslope outflow edge; If the fourth judgment result is no, then judging whether the elevation point in the target flow field cell is lower than the elevation point in the adjacent flow field cell, and obtaining a fifth judgment result; If the fifth judgment result is yes, determining that the i-th edge of the target flow field cell is an uphill inflow edge; If the fifth judgment result is no, determining that the i-th edge of the target flow field cell is a valley bottom sink edge or a ridge edge; According to the edge category of each flow field cell, the flow field cell is subjected to confluence analysis to determine the category of each flow field cell, including: If the target flow field cell contains a downslope outflow edge and an upslope inflow edge, and does not contain a valley bottom catchment edge and a ridge edge, the target flow field cell is determined as a slope unit; If the target flow field cell contains a valley bottom sink edge, the target flow field cell is determined as a valley bottom sink unit; If the target flow field cell contains a ridge edge, and contains a downslope outflow edge and an upslope inflow edge, the target flow field cell is determined as a ridge boundary cell; If the target flow field cell contains a boundary edge or a ridge edge, and contains a downslope outflow edge, but does not contain an upslope inflow edge, the target flow field cell is determined to be a ridge divergence cell.

2. A flow field cell division and confluence link identification device for characterizing three-dimensional terrain and water system extraction, characterized in that: The device applies the method according to claim 1, and the device comprises: The elevation point sampling module is used to perform B-spline processing and equally spaced point interpolation on the watershed contour lines to obtain equally spaced elevation points on the watershed contour lines; A flow field cell division module is used to divide irregular flow field cells using Thiessen polygons with equally spaced elevation points on the contour lines of the catchment area as the center, and obtain a Voronoi diagram of the catchment area; the Voronoi diagram is a cell chain with flow direction and outflow distribution coefficients composed of Thiessen polygons, the cell chain includes a plurality of flow field cells, and the flow field cells are represented by Thiessen polygons; An edge category module is used to classify and analyze the flow field cells in the Voronoi diagram based on the plane potential flow theory to obtain the edge category of each flow field cell; the edge category is streamline edge, uphill inflow edge, downhill outflow edge, ridge edge, valley bottom water collection edge or boundary edge; A flow field cell category recognition module is used to perform confluence analysis on the flow field cells according to the edge category of each flow field cell to determine the category of each flow field cell; the category of the flow field cell is a ridge boundary cell, a slope cell, a ridge divergent cell or a valley bottom convergent cell; The river network extraction module is used to demonstrate the water flow field of the Voronoi diagram according to the category of each flow field cell and extract the river network of the catchment area.

3. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the flow field cell division and confluence link identification method for characterizing three-dimensional terrain and water system extraction as described in claim 1.

4. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for flow field cell division and confluence link identification for characterizing three-dimensional terrain and water system extraction as described in claim 1 is implemented.

5. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the method for flow field cell division and confluence link identification for characterizing three-dimensional terrain and water system extraction as described in claim 1 is implemented.

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