A multi-resolution river network spatial data fusion integration method

Abstract

The application provides a multi-resolution river network spatial data fusion integration method, comprising the following steps: extracting river sections from a hydroriver data set and integrating the river sections into complete rivers; selecting an OSM river center line associated with each hydroriver from an OSM river center line layer; fusing the OSM river center line coordinates into the hydroriver; repairing the topological relationship of each hydroriver; and screening and manually repairing abnormal river sections. The multi-resolution river network spatial data fusion integration method provided by the application discriminates river similarity through various constraints such as spatial distance and topological relationship, and then realizes the fusion of rivers of different resolutions by using multiple distances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of remote sensing target recognition, and particularly relates to a multi-resolution river network spatial data fusion integration method. BACKGROUND

[0002] With the continuous progress of satellite remote sensing, unmanned aerial vehicle and other large-scale data acquisition technologies, data production methods are gradually diversified, forming various data resources of different sources and resolutions. While the data resources are constantly enriched, the conflict problems between similar data of different sources have brought great inconvenience to data users. At present, river data production mainly includes two methods, the first method is based on high-resolution terrain data, using GIS software, according to the hydrological flow concentration relationship, the river center line and topological network with topological relationship are generated; the second method is to use high-resolution remote sensing image, through image classification or manual plotting method, the river center line or river surface data is obtained. The river data obtained by the two methods has advantages and disadvantages, the river data extracted by using terrain data has good topological relationship, and has obvious advantages in hydrological calculation, but due to the influence of terrain precision, the spatial precision of river center line is low, especially in flat areas, there is obvious deviation between river line and actual river trend; the river data obtained by using high-resolution remote sensing image has high spatial resolution, but since many rivers are seasonal rivers, it is impossible to obtain complete river from remote sensing image, especially in dry season, it is difficult to extract continuous river from remote sensing image, in addition, the topological relationship of river cannot be obtained from remote sensing image, so it can only be applied to display and cannot meet the needs of professional aspects such as hydrological simulation and analysis. At present, the two types of river data that are most concerned and applied most are hydroriver river and river data in OSM (‌OpenStreetMap dataset, referred to as OSM), both of which realize global coverage. hydroriver mainly uses terrain data extraction, has very accurate and perfect topological relationship, including river flow direction, flow concentration area, length and other information; the OSM river layer is drawn by many users according to remote sensing map or high-precision map transfer, and has high spatial resolution, but lacks topological relationship between rivers, and many rivers are missing, and the data standardization is not enough.

[0003] The patent application with the application number CN107423753A discloses a fast fusion operation method for multi-source spatial data, which comprises the following steps: data format conversion, data rasterization, data normalization and data fusion. Different formats of data are converted into NetCDF network universal data format raster data files, R language program design is applied, a unified spatial resolution and raster coordinates are adopted for different raster data layers, each layer of raster data is standardized, and normalized data sources at the same spatial geographic position are obtained. The resolution and spatial geographic grid of data layers of different sources and different formats are unified, the research area vector polygon is used to cut different data layers through R language program design, and polygon NetCDF format data layers are obtained. According to the research target, corresponding weight coefficients are given to each data layer, a mathematical model is established, and the spatial distribution of the target function is obtained through numerical operation according to the model. The disadvantage of this method is that it is based on the traditional idea of extracting vectors from raster data, and the raster vector superposition is used for analysis, so that multi-resolution vector data fusion cannot be performed.

[0004] The article with the title of Research and Application of River Data Fusion Technology Considering Spatial Relationship, published in the 11th issue of Guangdong Water Resources and Hydropower in November 2021, discloses a research and application of river data fusion technology considering spatial relationship. The article is based on river coding and digital elevation model, establishes one-to-many or many-to-one correlation mapping between river reaches and between rivers and river-related projects, and automatically aggregates spatial, attribute and video data, and proposes a river data fusion technology considering spatial relationship, which systematically reflects the spatial relationship between rivers and river-related objects. It is expected to reduce the cost of river spatial data correlation processing and improve the application value of river spatial data. The disadvantage of this method is that it processes single-class river data, uses spatial relationship to realize river data integration and relationship establishment between water conservancy projects, and cannot perform multi-class different resolution river data fusion. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a multi-resolution river network spatial data fusion integration method, which discriminates river similarity through spatial distance, topological relationship and other constraints, and then realizes fusion of different resolution rivers by using multiple distances.

[0006] The purpose of the present application is to provide a multi-resolution river network spatial data fusion integration method, which comprises extracting river reaches from a hydroriver data set and integrating them into complete rivers, and further comprises the following steps:

[0007] Step 1: selecting an OSM river center line associated with each hydroriver river from an OSM river center line layer;

[0008] Step 2: fusing the OSM river center line coordinates into the hydroriver river;

[0009] Step 3: Repair the topology relationship of each hydroriver;

[0010] Step 4: Screen and manually repair abnormal river sections.

[0011] Preferably, the extracting river sections from the hydroriver dataset and integrating into complete rivers comprises the following sub-steps:

[0012] Step 01: Save the river sections in a separate layer from hydroriver, in which the rivers are divided into many river sections;

[0013] Step 02: Integrate the river sections into complete rivers according to the confluence relationship of the river sections.

[0014] Preferably in any of the above solutions, the river section integration method comprises tracing back from the terminal river section to the upstream until the uppermost source river section, accumulating the total length of each source river section to the terminal river section, and integrating all river sections from the source river section with the largest total length to the terminal river section into a complete river.

[0015] Preferably in any of the above solutions, the step 02 comprises the following sub-steps:

[0016] Step 021: Integrate all river sections of the inflow river as new terminal river sections according to the river section integration method to obtain all first-level rivers;

[0017] Step 022: Integrate all river sections of the inflow first-level river as new terminal river sections according to the river section integration method to obtain all second-level rivers;

[0018] Step 023: Integrate the river sections of the inflow second-level river as terminal river sections according to the river section integration method to obtain all third-level rivers;

[0019] Step 024: Integrate all river sections into complete rivers according to the river section integration method;

[0020] Step 025: After completing the integration of all rivers, use the encoding of the source river section as the encoding of the river.

[0021] Preferably in any of the above solutions, the step 1 comprises the following sub-steps:

[0022] Step 11: Make a 5km distance buffer zone for each hydroriver complete river, and select the OSM river centerline intersecting the buffer zone as the candidate river centerline of the river;

[0023] Step 12: Calculate the average distance, the number of nearest points, the proportion of nearest points, and the direction angle between each OSM river center line and the hydroriver river associated therewith, densify all hydroriver rivers and OSM center lines by using the densify tool of ArcGIS, and set the densification distance to 100 meters;

[0024] Step 13: Screen the OSM center lines according to the average distance, the number of nearest points, the proportion of nearest points, and the direction angle, and screen out OSM center lines that meet the selection conditions;

[0025] Step 14: After selecting the OSM center line, sort the center line corresponding to each hydroriver river.

[0026] In any of the above schemes, preferably, the calculation formula of the average distance is:

[0027]

[0028] d min(n) =min(d n,1 ,d n,2 ,……d n,t )

[0029] Wherein, D ave is the average distance of an OSM center line to the corresponding hydroriver river, m is the node number of the OSM center line, n is the node serial number, d min(n) is the nearest distance of the node n of the OSM center line to the hydroriver river, and d n,t is the distance between the node n of the OSM center line and the node t of the hydroriver.

[0030] In any of the above schemes, preferably, the distance d i,j between two nodes is calculated by:

[0031]

[0032] Wherein, x i and y i are the x and y coordinates of the i node respectively, and x j and y j are the x and y coordinates of the j node respectively.

[0033] In any of the above schemes, preferably, for each hydroriver, traverse each node on the river, calculate all nodes of all OSM center lines associated, find the nearest node corresponding to each hydroriver node, and record the OSM center line where the nearest node is located, and then aggregate to obtain the number C of nearest nodes on each OSM center line near .

[0034] In any of the above schemes, preferably, the nearest node ratio P of each OSM center line near The calculation formula is:

[0035]

[0036] Wherein, C total is the total number of nodes on the OSM center line.

[0037] In any of the above schemes, preferably, the calculation method of the direction angle is:

[0038] Step 121: Calculate the angle of each OSM center line;

[0039] Step 122: Find the nearest node on the hydroriver from the first node and the last node on the OSM center line, and record the node numbers as a and b respectively, and calculate the angle of the hydroriver corresponding to the OSM center line;

[0040] Step 123: Calculate the center line angle of the OSM center line and the hydroriver;

[0041] Step 124: Control the center line angle within 90°.

[0042] In any of the above schemes, preferably, the calculation formula of the angle of each OSM center line is

[0043]

[0044] Wherein, atan is the inverse tangent function in trigonometric function, x start , y start is the x, y coordinate of the first node on the OSM center line, x end , y end is the x, y coordinate of the last node on the OSM center line, when x end =x start , A osm =90°.

[0045] In any of the above schemes, preferably, the calculation formula of the angle of the hydroriver corresponding to the OSM center line is

[0046]

[0047] wherein x a , y a are the x, y coordinates of a node numbered a on the hydroriver, x b , y b are the x, y coordinates of a node numbered b on the hydroriver, and when x a = x b , A osm = 90°.

[0048] In any of the above solutions, preferably, the formula for calculating the centerline included angle is:

[0049] A diff = |A osm -A hydro |

[0050] When A diff ≥ 360°, A diff = A diff - 360°.

[0051] When 360° ≥ A diff > 180°, A diff = 360° - A diff .

[0052] When 180° ≥ A diff > 90°, A diff = 180° - A diff .

[0053] When 90° ≥ A diff > 0°, A diff = A diff .

[0054] In any of the above solutions, preferably, the selection condition is

[0055] D ave < 1000 and C near > 50 and P near > 0.4 and A diff < 20°.

[0056] In any of the above solutions, preferably, the step 14 comprises calculating the node number of each OSM centerline node to the nearest hydroriver node, calculating the average value of the node number on the hydroriver corresponding to each OSM centerline node, and sorting the OSM centerlines in descending order of the average value.

[0057] In any of the above solutions, preferably, the step 2 comprises the following sub-steps:

[0058] Step 21: Eliminate hydroriver segments that do not need to be fused.

[0059] Step 22: For hydroriver segments that need coordinate modification, modify the coordinates of each node one by one.

[0060] Step 23: According to the node order of the hydroriver segment, find the nearest OSM centerline node one by one.

[0061] In any of the above solutions, preferably, the step 21 comprises calculating the nearest distance d of all nodes of each hydroriver segment to the nodes of the associated OSM centerline. min When d min >2000, it is determined that the node cannot find the nearest node.

[0062] In any of the above solutions, preferably, the step 21 further comprises if there are more than 20 nodes at the front or back of a certain hydroriver segment that cannot find the nearest node, it is determined that the segment does not need to be modified, and the node coordinate modification is not performed.

[0063] In any of the above solutions, preferably, the step 22 comprises numbering the nodes on the OSM centerline associated with the hydroriver, and the numbering order gradually increases from upstream to downstream.

[0064] In any of the above solutions, preferably, the step 23 comprises when the distance between two points is less than 2000, it is determined that the nearest point is found, and the following two cases are handled,

[0065] Case 1: If the code of the found OSM centerline node code2 is continuous with the code of the previous hydroriver node code1, i.e. code2=code1 or code2-code1=1, replace the coordinates of the hydroriver segment node with the coordinates of the OSM centerline node.

[0066] Case 2: If the code of the found OSM center point code2 is not continuous with the code of the previous hydroriver node code1, i.e. code2-code1>1, add the OSM centerline nodes from code1+1 to code2-1 to the hydroriver segment, and replace the coordinates of the hydroriver segment node with the coordinates of the code2 node.

[0067] In any of the above solutions, preferably, the step 3 comprises traversing each river segment in the hydroriver, and when there is a case that one of the adjacent river segments is modified in coordinates and one is not, moving the end point of the modified river segment to the end point of the unmodified river segment.

[0068] In any of the above solutions, preferably, the step 4 comprises calculating the length change of each river segment before and after modification, and the formula is:

[0069] L diff =|L new -L orgin |

[0070]

[0071] wherein, L diff is the absolute value of the length change of the river before and after modification, L ratio is the proportion of the length change of the river before and after modification, L new is the length after modification, L orgin is the length before modification.

[0072] In any of the above solutions, preferably, when L diff >2000 or L ratio >0.2, it is determined that the change before and after repair exceeds the expectation, and then a comparison check is performed through high-definition remote sensing images to determine whether the modified river matches the river in the remote sensing images, and if the modification result does not match the remote sensing images, manual repair is performed according to the topological relationship and in combination with the remote sensing images.

[0073] The present application proposes a multi-resolution river network spatial data fusion integration method, which can maintain the topological relationship of the river network and improve the spatial resolution of the river data.

[0074] HydroRIVERS is a global river network data project developed by the World Wildlife Fund (WWF) in cooperation with many international institutions, aiming to provide high-precision river network data through satellite and topographic data analysis.

[0075] OSM, OpenStreetMap dataset, is an open-source global collaborative map project. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1 is a flow chart of a preferred embodiment of the multi-resolution river network spatial data fusion integration method according to the present application.

[0077] Figure 2This is a flowchart of another preferred embodiment of the multi-resolution river network spatial data fusion and assimilation method according to the present invention. Detailed Implementation

[0078] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0079] Example 1

[0080] like Figure 1 As shown, a multi-resolution river network spatial data fusion and assimilation method, performing step 1000, extracts river segments from the hydroriver dataset and integrates them into a complete river, including the following sub-steps:

[0081] Perform step 1010 to save the river segment from hydroriver in a separate layer, in which the river is divided into many segments;

[0082] Step 1020 involves integrating the river segments into a complete river based on their confluence relationships. The method for integrating the river segments includes tracing back upstream from the end segment to the upstream source segment, accumulating the total length from each source segment to the end segment, and integrating all river segments from the source segment to the end segment with the longest total length into a complete river.

[0083] Step 1020 includes the following sub-steps:

[0084] Execute step 1021, taking all river segments flowing into the river as new terminal river segments, and integrate them according to the river segment integration method to obtain all first-level rivers;

[0085] Execute step 1022, taking all river segments flowing into the first-level rivers as new terminal river segments, and integrating them according to the river segment integration method to obtain all second-level rivers;

[0086] Execute step 1023, taking the river sections flowing into the secondary rivers as the terminal rivers, and integrate them according to the river section integration method to obtain all the tertiary rivers;

[0087] Execute step 1024 to integrate all river segments into a complete river according to the described river segment integration method;

[0088] After completing step 1025 and integrating all rivers, the code of the source river section will be used as the code of the river.

[0089] Perform step 1100, selecting the OSM river centerline associated with each hydroriver from the OSM river centerline layer, including the following sub-steps:

[0090] Step 1110 is performed to make a 5km distance buffer for each hydroriver complete river, and select the OSM river centerline intersecting with the buffer as the candidate river centerline of the hydroriver.

[0091] Step 1120 is performed to calculate the average distance, the number of nearest points, the proportion of nearest points, and the direction angle of each OSM river centerline and the hydroriver river associated therewith. The densify tool of ArcGIS is used to encrypt the nodes of all hydroriver rivers and OSM centerlines, and the encryption distance is set to 100 meters.

[0092] The calculation formula of the average distance is:

[0093]

[0094] d min(n) =min(d n,1 ,d n,2 ,……d n,t )

[0095] wherein D ave is the average distance of an OSM centerline to the corresponding hydroriver river, m is the number of nodes of the OSM centerline, n is the node number, d min(n) is the nearest distance of the node n of the OSM centerline to the hydroriver river, and d n,t is the distance of the node n of the OSM centerline to the node t of the hydroriver.

[0096] The distance d i,j between two nodes is calculated as follows:

[0097]

[0098] wherein x i and y i are the x and y coordinates of the i node, and x j and y j are the x and y coordinates of the j node.

[0099] For each hydroriver river, each node on the river is traversed, all nodes of all OSM centerlines associated therewith are calculated, the nearest node corresponding to each hydroriver node is found, the OSM centerline on which the nearest node is located is recorded, and then the number C near of nearest nodes on each OSM centerline is summarized.

[0100] The calculation formula of the nearest point proportion P near of each OSM centerline is:

[0101]

[0102] wherein C total is the total number of nodes on the OSM centerline.

[0103] The calculation method of the direction included angle is:

[0104] Step 1121 is performed to calculate the included angle of each OSM centerline, and the calculation formula is

[0105]

[0106] wherein atan is the inverse tangent function in trigonometry, x start , y start are the x, y coordinates of the first node on the OSM centerline, x end , y end are the x, y coordinates of the last node on the OSM centerline, when x end =x start , A osm =90°.

[0107] Step 1122 is performed to find the nearest nodes to the first node and the last node on the OSM centerline on the hydroriver, and the node numbers are recorded as a and b, respectively, and the angle of the OSM centerline corresponding to the hydroriver is calculated, and the calculation formula is

[0108]

[0109] wherein x a , y a are the x, y coordinates of the node numbered a on the hydroriver, x b , y b are the x, y coordinates of the node numbered b on the hydroriver, when x a =x b , A osm =90°

[0110] Step 1123 is performed to calculate the included angle of the centerline of the OSM centerline and the hydroriver, and the calculation formula is:

[0111] A diff =|A osm -A hydro |.

[0112] Step 1124 is performed to control the centerline included angle to be within 90°,

[0113] when Adiff ≥ 360°, A diff = 360° - A diff - 360°;

[0114] When 360° ≥ A diff > 180°, A diff = 360° - A diff ;

[0115] When 180° ≥ A diff > 90°, A diff = 180° - A diff ;

[0116] When 90° ≥ A diff > 0°, A diff = A diff .

[0117] Step 1130 is performed to filter the OSM center lines according to the average distance, the number of nearest points, the proportion of nearest points, and the direction angle, and filter out OSM center lines that meet the selection conditions, the selection conditions being

[0118] D ave < 1000 and C near > 50 and P near > 0.4 and A diff < 20°.

[0119] Step 1140 is performed to sort the center lines corresponding to each hydroriver after selecting the OSM center lines, including calculating the number of nodes of each OSM center line to the nearest hydroriver node, calculating the average value of the node number on the hydroriver corresponding to each OSM center line node, and sorting the OSM center lines in descending order of the average value.

[0120] Step 1200 is performed to fuse the OSM river center line coordinates into the hydroriver, including the following sub-steps:

[0121] Step 1210 is performed to eliminate hydroriver sections that do not need to be fused, including calculating the nearest distance d min of all nodes of each hydroriver section and the nodes of the associated multiple OSM center lines. min When d min > 2000, it is determined that the node cannot find the nearest node; if there are more than 20 nodes at the front or back end of a hydroriver section that cannot find the nearest node, it is determined that the river section does not need to be modified, and the node coordinates are not modified.

[0122] Performing step 1220, modifying the coordinates of each node of the hydroriver section that needs coordinate modification, including numbering the nodes on the OSM centerline associated with the hydroriver river in ascending order from upstream to downstream.

[0123] Performing step 1230, sequentially searching for the nearest OSM centerline node according to the node order of the hydroriver section, including when the distance between two points is less than 2000, it is determined that the nearest point is found, and the following two cases are handled,

[0124] Case 1: If the number code2 of the OSM centerline node found is continuous with the number code1 of the OSM centerline node found by the previous hydroriver node, i.e. code2=code1 or code2-code1=1, then replace the coordinates of the hydroriver section node with the coordinates of the OSM centerline node.

[0125] Case 2: If the number code2 of the OSM center point found is not continuous with the number code1 of the OSM centerline node found by the previous hydroriver node, i.e. code2-code1>1, then add the OSM centerline nodes from code1+1 to code2-1 to the hydroriver section, and replace the coordinates of the hydroriver section node with the coordinates of the code2 node.

[0126] Performing step 1300, repairing the topology relationship of each hydroriver river, including traversing each section in the hydroriver river, and when there is a situation where one of the adjacent sections has been modified in coordinates and one has not been modified in coordinates, moving the end point of the modified section to the end point of the unmodified section

[0127] Performing step 1400, screening and manually repairing abnormal sections, including calculating the length change of each section before and after modification, the formula is:

[0128] L diff =|L new -L orgin |

[0129]

[0130] Where, L diff is the absolute value of the length change of the river before and after modification, L ratio is the length change ratio of the river before and after modification, L new is the modified length, Lorgin Length before modification.

[0131] When L diff >2000 or L ratio >0.2, it is determined that the change before and after repair exceeds the expectation, and the comparison inspection is performed through the high-definition remote sensing image to determine whether the modified river matches the river in the remote sensing image, and if the modification result does not match the remote sensing image, manual repair is performed according to the topological relationship and in combination with the remote sensing image.

[0132] Example two

[0133] The application provides a different source river data fusion integration method, which maintains the topological relationship of the river network and improves the spatial resolution of the river data, discriminates the river similarity through various constraints such as spatial distance and topological relationship, and then realizes the fusion of different resolution rivers through multiple distances.

[0134] As Figure 2 shown, a multi-resolution river network spatial data fusion integration method comprises the following steps:

[0135] First, extract the river section from the hydroriver data set and integrate it into a complete river.

[0136] First, save the river section in a separate layer from hydroriver, and the river in the layer is divided into many river sections;

[0137] Second, according to the confluence relationship of the river section, the river section is integrated into a complete river. The specific method is as follows: from the end river section (i.e. the most downstream river section of a river, generally the most downstream river section of an inlet sea, inlet lake or inland river) to the upstream, until the source river section at the most upstream. In this way, each end river section will correspond to multiple source river sections. Add the total length of each source river section to the end river section, and integrate all river sections from the source river section with the largest total length to the end river section into a complete first-level river. Then, all river sections flowing into the first-level river are taken as new end river sections, and all second-level rivers are obtained according to the above method. Then, the river sections flowing into the second-level river are taken as end river sections, and all third-level rivers are obtained. In this way, all river sections are integrated into complete rivers. After completing the integration of all rivers, the code of the source river section is taken as the code of the river.

[0138] Finally, according to the order from upstream to downstream, all river sections contained in each complete river in the layer are sorted. The source river section is the first river section, the flowing-in river section is the second river section, and the sorting is performed in sequence until the end river section of the river.

[0139] The second step is to select the river center line associated with each hydroriver from the OSM river center line layer.

[0140] First, a 5km buffer zone is made for each hydroriver complete river, and the OSM river centerlines intersecting with the buffer zone are selected as the candidate river centerlines of the hydroriver.

[0141] Second, the average distance, the number of nearest points, the proportion of nearest points, and the direction angle of each OSM river centerline and its associated hydroriver are calculated.

[0142] Using the densify tool of ArcGIS, all hydroriver rivers and OSM centerlines are node-encrypted, and the encryption distance is set to 100 meters.

[0143] (1) Average distance

[0144]

[0145] d min(n) =min(d n,1 ,d n,2 ,……d n,t )

[0146] In the formula, D ave represents the average distance of an OSM centerline to the corresponding hydroriver; m represents the number of nodes of the OSM centerline, n represents the node number, d min(n) represents the nearest distance of node n of the OSM centerline to the hydroriver; d n,t represents the distance from node n of the OSM centerline to node t of the hydroriver.

[0147] The distance calculation method of two nodes is:

[0148]

[0149] In the formula, x i , y i represent the x and y coordinates of node i, respectively, and x j , y j represent the x and y coordinates of node j, respectively.

[0150] (2) Number of nearest points

[0151] For each hydroriver river, traverse each node on the river, calculate all nodes of all associated OSM centerlines, find the nearest node corresponding to each hydroriver node, and record the OSM centerline where the nearest node is located. Then summarize the number of nearest nodes on each OSM centerline (C near ).

[0152] (3) The nearest node ratio of the OSM centerline

[0153] The nearest node ratio of each OSM centerline is calculated.

[0154]

[0155] In the formula, C near represents the number of nearest nodes on the OSM centerline, C total represents the total number of nodes on the OSM centerline.

[0156] (4) The direction angle of the OSM centerline

[0157] First, the angle A of each OSM centerline is calculated.

[0158]

[0159] In the formula, atan is the inverse tangent function in trigonometry, x start , y start represent the x, y coordinates of the first node on the OSM centerline, x end , y end represent the x, y coordinates of the last node on the OSM centerline. If x end = x start , A osm = 90.

[0160] The nearest nodes on the hydroriver to the first and last nodes on the OSM centerline are found, and the node numbers are recorded as a and b, respectively. The angle of the OSM centerline corresponding to the hydroriver is calculated.

[0161]

[0162] In the formula, atan is the inverse tangent function in trigonometry, x a , y a represent the x, y coordinates of the node with number a on the hydroriver, x b , y b represent the x, y coordinates of the node with number b on the hydroriver. If x a = x b , then A osm = 90.

[0163] The angle between the OSM centerline and the centerline of the hydroriver is calculated.

[0164] A diff = |A osm -A hydro|

[0165] Then the following three-step process is performed in turn to control the included angle within 90:

[0166] If, A diff > 360, A diff = A diff - 360;

[0167] If, A diff > 180, A diff = 360 - A diff ;

[0168] If, A diff > 90, A diff = 180 - A diff .

[0169] According to the average distance, the number of nearest points, the nearest point ratio, and the direction included angle, the OSM center line is screened, and the OSM center line satisfying the following conditions is screened out:

[0170] D ave < 1000 and C near > 50 and P near > 0.4 and A diff < 20

[0171] After selecting the OSM center line, the center line corresponding to each hydroriver is sorted. The processing method is to calculate the number of the node of each OSM center line to the nearest hydroriver node (since the hydroriver section has been sorted, the number is gradually increasing from upstream to downstream), and then calculate the average value of the node number corresponding to the node of each OSM center line on the hydroriver, and sort the OSM center line according to the average value from large to small.

[0172] Thirdly, the OSM center line coordinates are fused into the hydroriver.

[0173] In order to maintain the topological information of the hydroriver and fuse the high-precision OSM center line into the hydroriver, the method of moving the node of the hydroriver to the nearest OSM center line node is adopted. The method is to take the river section in the hydroriver as a unit and process it by river section.

[0174] Firstly, the hydroriver section that does not need to be fused is removed. The nearest distance d min , if dmin If the distance between the two points is less than 2000, it is considered that the node has found the nearest node. If more than 20 nodes at the front or back of a hydroriver segment cannot find the nearest node, it is considered that the segment does not need to be modified, and the following node coordinate modification will not be performed.

[0175] Secondly, for the hydroriver segment that needs coordinate modification, modify the coordinates of each node. Before modification, the nodes on the OSM center line associated with the hydroriver are numbered, and the numbering order is gradually increasing from upstream to downstream.

[0176] According to the node order of the hydroriver segment, the nearest OSM center line node is found in turn. If the distance between the two points is less than 2000, it is considered that the nearest node is found, and then two cases are handled:

[0177] The first case: if the code of the OSM center line node found (code2) is continuous with the code of the OSM center line node found by the previous hydroriver node (code1) (code2=code1 or code2-code1=1), replace the coordinates of the hydroriver segment node with the coordinates of the OSM center line node.

[0178] The second case: if the code of the OSM center point found (code2) is not continuous with the code of the OSM center line node found by the previous hydroriver node (code1) (code2-code1>1), add the OSM center line nodes from code1+1 to code2-1 to the hydroriver segment, and replace the coordinates of the hydroriver segment node with the coordinates of the code2 node.

[0179] Fourthly, repair the topology relationship of each hydroriver.

[0180] Traverse each segment in the hydroriver. If there is a coordinate modification and a non-coordinate modification between adjacent segments, move the end point of the modified segment to the end point of the non-modified segment to ensure the connectivity of the two segments.

[0181] Fifthly, screen and manually repair abnormal segments.

[0182] Calculate the length change of each segment before and after modification:

[0183] L diff =|L new -L orgin |

[0184]

[0185] In the formula, L new represents the modified length, L orgin represents the length before modification, in meters.

[0186] If L diff >2000 or L ratio >0.2, it is considered that the change before and after the repair is large, and the river section needs to be checked, and if the modification is unreasonable, manual repair is performed according to the topological relationship and combined with remote sensing images.

[0187] In order to better understand the present application, the above is described in detail in combination with the specific embodiments of the present application, but is not a limitation on the present application. Any simple modification made to the above embodiments according to the technical essence of the present application still belongs to the scope of the technical scheme of the present application. In the specification, each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to. For system embodiments, since they basically correspond to method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the method embodiment.

Claims

1. A method for fusion and assimilation of multi-resolution river network spatial data, comprising extracting river segments from the hydroriver dataset and integrating them into a complete river, characterized in that, It also includes the following steps: Step 1: Select the OSM river centerline associated with each hydroriver from the OSM river centerline layer, including the following sub-steps: Step 11: Create a 5km buffer zone for each complete hydroriver, and select the OSM river centerline that intersects with the buffer zone as the alternative river centerline for that river; Step 12: Calculate the average distance, number of nearest points, proportion of nearest points, and directional angle between the centerline of each OSM river and its associated hydroriver river. Using ArcGIS's densify tool, densify the nodes of all hydrorivers and OSM centerlines, with the densification distance set to 100 meters. The formula for calculating the average distance is: ， the min(n) =min(d n,1 ,d n,2 ,……d n,t ), Among them, D ave Let m be the average distance from the OSM centerline to the corresponding hydroriver, m be the number of nodes on the OSM centerline, n be the node number, and d be the average distance from the OSM centerline to the corresponding hydroriver. min(n) Let d be the shortest distance from node n on the OSM centerline to the hydroriver. n,t This is the distance from node n on the OSM centerline to node t on the hydroriver; The distance d between the two nodes i,j The calculation method is as follows: ， Where, x i y i These are the x and y coordinates of node i, respectively. j y j These are the x and y coordinates of node j, respectively; Step 13: Filter OSM centerlines based on four values: average distance, number of nearest points, proportion of nearest points, and direction angle, and select OSM centerlines that meet the selection criteria. Step 14: After selecting the OSM centerline, sort the centerlines corresponding to each hydroriver. Step 2: Integrate the OSM river centerline coordinates into the hydroriver river; Step 3: Repair the topology of each hydroriver; Step 4: Filter and manually repair abnormal river sections.

2. The multi-resolution river network spatial data fusion and assimilation method as described in claim 1, characterized in that, The process of extracting river segments from the hydroriver dataset and integrating them into a complete river system includes the following sub-steps: Step 01: Save the river segments from HydroRiver in a separate layer, where the river is divided into many segments; Step 02: Based on the confluence relationship of the river sections, integrate the river sections into a complete river.

3. The multi-resolution river network spatial data fusion and assimilation method as described in claim 2, characterized in that, The river segment integration method involves tracing back upstream from the end of the river segment to the source segment at the very top, accumulating the total length from each source segment to the end segment, and integrating all river segments from the source segment to the end segment with the longest total length into a complete river.

4. The multi-resolution river network spatial data fusion and assimilation method as described in claim 3, characterized in that, Step 02 includes the following sub-steps: Step 021: Take all the river segments flowing into the river as new terminal river segments, and integrate them according to the river segment integration method to obtain all first-level rivers; Step 022: Take all the river segments flowing into the first-level rivers as new terminal river segments, and integrate them according to the river segment integration method to obtain all the second-level rivers; Step 023: Take the river sections flowing into the secondary rivers as the terminal rivers, and integrate them according to the river section integration method to obtain all the tertiary rivers; Step 024: Integrate all river segments into a complete river according to the described river segment integration method; Step 025: After completing the integration of all rivers, use the code of the source section as the code of the river.

5. The multi-resolution river network spatial data fusion and assimilation method as described in claim 4, characterized in that, For each hydroriver, traverse every node on the river, calculate all nodes on all associated OSM centerlines, find the nearest point for each hydroriver node, and record the OSM centerline where the nearest point is located. Then, sum up to obtain the number C of nearest nodes on each OSM centerline. near .

6. The multi-resolution river network spatial data fusion and assimilation method as described in claim 5, characterized in that, The nearest point ratio P of each OSM centerline near The calculation formula is: ， Among them, C total This represents the total number of nodes along the OSM centerline.

7. The multi-resolution river network spatial data fusion and assimilation method as described in claim 6, characterized in that, The method for calculating the included angle is as follows: Step 121: Calculate the included angle of each OSM centerline; Step 122: Find the nearest nodes on the hydroriver to the first and last nodes on the OSM centerline, and record the node numbers as a and b respectively. Calculate the angle of the hydroriver corresponding to the OSM centerline. Step 123: Calculate the angle between the OSM centerline and the hydroriver centerline; Step 124: Control the included angle of the center line to within 90°.

8. The multi-resolution river network spatial data fusion and assimilation method as described in claim 7, characterized in that, The formula for calculating the angle between each OSM centerline is: ， Where atan is the inverse cotangent function in trigonometric functions, x start y start Let x and y be the coordinates of the first node on the OSM centerline, x end y end Let x and y be the coordinates of the last node on the OSM centerline, when x end =x start At that time, A osm =90°.

Images