Urban drainage system visualization processing method based on pipe network generalization model

Abstract

The invention relates to an urban drainage system visualization processing method based on a pipe network generalization model. A drainage system framework model for expressing the overall spatial distribution form of a whole urban drainage system, a drainage system generalization model for reflecting the upstream and downstream topological relation of a sewage plant and a drainage pump station and the relation between a connected main pipeline and a main pipe, and a drainage system topological model capable of reflecting the layout of an underground sewage system in a city and the flow direction of sewage are constructed; and then on the basis of the drainage system topology model, schematic physical expression is performed on a pipe network relationship in the obtained drainage system topology model by utilizing two geometric forms of points and lines to realize visual display of the urban underground drainage system, so that the problems that the urban underground pipe network cannot be seen and cannot be used are effectively solved, and the urban underground drainage system can be visually displayed. The overall topological relation and the global operation state of the urban underground drainage system are truly and comprehensively reflected, and the requirements of various industry departments of novel smart city construction for spatialized display and analysis application of underground pipeline data are met.

Description

Technical Field

[0001] The present invention relates to the field of underground pipe network data processing, and in particular to a visualization processing method for urban drainage systems based on a pipe network generalization model. Background Art

[0002] The urban underground drainage system is an important part of the urban pipe network system and is of great significance for ensuring the normal operation of the city.

[0003] In the existing management process of urban underground drainage systems, there has long been a phenomenon of multi-headed management where multiple departments (such as pipe network design units, construction units, maintenance units, natural resources units, water conservancy units, and housing construction units, etc.) manage the drainage system separately, resulting in serious loss of data in the urban underground pipe network system and reducing the overall digital management level of the urban underground drainage system.

[0004] In addition, most of the pipeline data in the existing urban underground drainage systems still remains in the form of paper or CAD electronic documents for individual completed and maintained projects, which can only simply display the pipeline information in local areas of the urban underground drainage system and cannot truly and comprehensively reflect the overall topological relationship and global operating status of the urban underground drainage system, which is not conducive to the management of the urban underground drainage system. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a visualization processing method for urban drainage systems based on a pipe network generalization model in view of the above-mentioned prior art. The visualization processing method for urban drainage systems based on a pipe network generalization model can achieve a schematic visualization expression of the urban underground drainage system by constructing a hierarchical generalization model of the drainage pipe network of the urban drainage system.

[0006] The technical solution adopted by the present invention to solve the above technical problems is as follows: A visualization processing method for urban drainage systems based on a pipe network generalization model, characterized by comprising the following steps: Step 1, construct a drainage system framework model that expresses the overall spatial distribution form of the entire urban drainage system; wherein, the drainage system framework model takes the sewage treatment plant as the main node, the pumping stations that convey sewage to the sewage treatment plant as the backbone nodes, and the connections between the sewage treatment plant and each pumping station and between the pumping stations to schematically outline the drainage system line framework, thereby characterizing the sewage flow direction relationship characteristics within the entire system; Step 2, on the basis of the constructed drainage system framework model, construct a drainage system generalization model that reflects the upstream and downstream topological relationships of the sewage treatment plant and the drainage pumping stations and the relationship between the main pipelines and the branch pipelines that are connected to each other; wherein, the drainage system generalization model characterizes the sewage transportation route within the entire urban underground drainage system; Step 3: Simplify the constructed generalized drainage system model, and retain all the main pipelines that can reflect the layout of the urban underground sewage system and the sewage flow direction. Use the topological relationship formed by all the retained main pipelines as the drainage system topological model. Step 4: Based on the obtained drainage system topological model, use two geometric forms of points and lines to make a schematic physical expression of the pipe network relationship in the drainage system topological model, so as to realize the visual display of the urban underground drainage system.

[0007] Improved, in the method for visualizing the urban drainage system based on the pipe network generalization model, in Step 2, the process of obtaining the sewage transportation route in the entire urban underground drainage system includes Steps a1 to a4: Step a1: Obtain the pipe points and their accessory facility data of the underground drainage system obtained in the urban underground pipeline census work; among them, the pipe point data of the underground drainage system in the pipe point and their accessory facility data of the underground drainage system includes the attribute information that the pipe point is the starting point or the ending point of the pipeline. Step a2: Obtain the road centerlines in the urban electronic map basic database. Step a3: Perform an optimal matching process on the obtained pipe points and their accessory facility data of the urban underground drainage system and the obtained road centerlines to simulate the first and second level main pipelines and trunk pipeline routes representing the urban underground drainage system. Step a4: Retrieve the starting point information and ending point information of each pipe point of the obtained underground drainage system, and mark the sewage flow direction in each pipeline of the underground drainage system, forming a transportation route in which the sewage trunk pipeline transports sewage to the sewage main pipeline through the pumping station and finally transports the sewage to the sewage treatment plant.

[0008] Further improved, in the method for visualizing the urban drainage system based on the pipe network generalization model, in Step a3, the process of performing an optimal matching process on the obtained pipe points and their accessory facility data of the urban underground drainage system and the obtained road centerlines to simulate the first and second level main pipelines and trunk pipeline routes representing the urban underground drainage system includes the following steps: Step b1: Search for all road centerlines within the neighborhood of the set of pipe points to be matched; among them, the set of pipe points to be matched is formed by all the pipe points of the obtained urban underground drainage system. Step b2: Measure the similarity between the pipe point connection lines as pipe segments to each candidate road respectively. Step b3: Take the candidate road with the maximum similarity as the matching road, and use the road centerline of the matching road as the generalized linear expression of the pipe segment.

[0009] Furthermore, in the method for visualizing the urban drainage system based on the pipe network generalization model, the process of selecting the candidate road includes the following steps: Step c1: Select the maximum horizontal coordinate and the minimum vertical coordinate among all the pipe point coordinates in the pipe point set, and establish an enclosing rectangle with the selected maximum horizontal coordinate and minimum vertical coordinate as the boundaries. Step c2: Determine the error region: Incorporate the roads around the pipe point set into the area range where the current position error may exist; wherein, the radius of this area range is the maximum value among the distances from the center point of the enclosing rectangle to each pipe point in the pipe point set. Step c3: Take the road segment set located within this error region as the candidate roads in the pipe point set.

[0010] Furthermore, in the method for visual processing of urban drainage systems based on a pipe network generalization model, the determination process of the matching road is as follows: Step d1: Calculate the first node distance, the second node distance, and the perpendicular distance from the center point of the enclosing rectangle to each candidate road in the pipe point set; wherein, the first node distance of the candidate road is the distance from the center point of the enclosing rectangle to the starting point of the corresponding candidate road, the second node distance of the candidate road is the distance from the center point of the enclosing rectangle to the corresponding candidate road point, and the perpendicular distance of the candidate road is the distance from the center point of the enclosing rectangle to the foot of the perpendicular from the center point of the enclosing rectangle on the corresponding candidate road. Step d2: Calculate the angle between the center line of the enclosing rectangle and each candidate road. Step d3: Obtain the foot of the perpendicular from the center point of the enclosing rectangle to each candidate road in the pipe point set. Step d4: Make a judgment on whether the foot of the perpendicular is located on the candidate road: When the foot of the perpendicular is located on the candidate road, then take the perpendicular distance corresponding to this foot of the perpendicular as the distance from the center point of the enclosing rectangle to the corresponding candidate road, and transfer to Step d5; otherwise, select the minimum distance value from the first node distance and the second node distance, and take this minimum distance value as the distance from the center point of the enclosing rectangle to the corresponding candidate road, and transfer to Step d5. Step d5: Calculate the matching similarity between the pipe point set and the candidate roads; wherein, the calculation method of the matching similarity is as follows: s di =U d -λ d ·d i ; s ai =U a -λ a ·d i ; s i = s ai +s di ; λ a +λd = 1; wherein, s i represents the matching similarity between the pipe point set and candidate road i, s ai represents the angular matching similarity between the pipe point set and candidate road i, s di represents the distance matching similarity between the pipe point set and candidate road i, U a represents the maximum included angle between the center line of the circumscribed rectangle and all candidate roads, U d represents the maximum distance from the center point of the circumscribed rectangle to all candidate roads, λ a represents the weight of the distance, λ d represents the weight of the included angle; wherein, if the included angle between any road segment and the center line of the circumscribed rectangle exceeds U a or the distance between any road segment and the center point of the circumscribed rectangle exceeds U d , it is determined that there is no similarity between any road segment and the pipe point set, and this road segment is deleted from the candidate roads; Step d6, taking the candidate road corresponding to the matching similarity with the maximum matching similarity value as the matching road segment.

[0011] Further improvement, in this invention, the visualization processing method of the urban drainage system based on the pipe network generalization model further includes: collecting and classifying and reorganizing drainage facility data based on the urban underground drainage pipe network census database; and spatially positioning and coding the drainage pipe network topological model according to the whole process of sewage generation, collection, transportation, treatment and discharge.

[0012] Furthermore, in the visualization processing method of the urban drainage system based on the pipe network generalization model, the spatial positioning and coding process is as follows: Dividing drainage facilities into 5 basic categories: drainage households, pipe networks, pump stations, sewage treatment plants and drainage outlets; Assigning a unique code to each drainage facility based on a preset coding rule; wherein, the unique code uses an 18 - bit character coding, which is composed of 8 - bit spatial positioning codes, 6 - bit facility classification codes and 4 - bit sequence codes from left to right.

[0013] Compared with the prior art, the advantages of the present invention are as follows: The visualization processing method of the urban drainage system based on the pipe network generalization model of the present invention constructs a drainage system framework model that expresses the overall spatial distribution form of the entire urban drainage system, a drainage system generalization model that reflects the upstream and downstream topological relationships of sewage treatment plants and drainage pumping stations and the relationship between the main pipelines and trunk pipelines connected, and a drainage system topological model that can reflect the layout of the underground sewage system in the city and the sewage flow direction. Then, based on the obtained drainage system topological model, the pipe network relationship in the drainage system topological model is schematically physically expressed by using two geometric forms of points and lines, realizing the visualization display of the urban underground drainage system, thus effectively solving the problems of "invisible" and "useless" of urban underground pipe networks, truly and comprehensively reflecting the overall topological relationship and global operation state of the urban underground drainage system, and meeting the spatial display and analysis application requirements of underground pipeline data for various industry departments in the construction of new smart cities. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic flow chart of the visualization processing method of the urban drainage system based on the pipe network generalization model in the embodiment of the present invention; Figure 2 It is a schematic diagram of the error area determined in the embodiment of the present invention; Figure 3 It is a schematic diagram of the included angle between the center line of the circumscribed rectangle and each candidate road in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The present invention will be further described in detail below in conjunction with the embodiments of the drawings.

[0016] This embodiment provides a visualization processing method of an urban drainage system based on a pipe network generalization model. Specifically, as shown in Figure 1 The visualization processing method of the urban drainage system based on the pipe network generalization model of this embodiment includes the following steps 1 to 4: Step 1, construct a drainage system framework model that expresses the overall spatial distribution form of the entire urban drainage system; wherein, the drainage system framework model takes the sewage treatment plant as the main node, the pumping stations that transport sewage to the sewage treatment plant as the skeleton nodes, and the connection lines between the sewage treatment plant (or sewage treatment plant) and each pumping station and between the pumping stations schematically outline the drainage system line framework, thereby characterizing the sewage flow direction relationship characteristics within the entire system; Step 2, on the basis of the constructed drainage system framework model, construct a drainage system generalization model that reflects the upstream and downstream topological relationships of sewage treatment plants and drainage pumping stations and the relationship between the main pipelines and trunk pipelines that are connected to each other; wherein, the drainage system generalization model characterizes the sewage transportation route within the entire urban underground drainage system; Step 3: Simplify the constructed generalized model of the drainage system, and retain all the main pipelines that can reflect the layout of the urban underground sewage system and the sewage flow direction. Take the topological relationship formed by all the retained main pipelines as the topological model of the drainage system. Step 4: Based on the obtained topological model of the drainage system, use two geometric forms of points and lines to make a schematic physical expression of the pipeline network relationship in the topological model of the drainage system, so as to realize the visual display of the urban underground drainage system. For example, use two geometric forms of points and lines to make a schematic physical expression of the actual pipeline network, and different model display levels can also be set according to different display scales. Among them, the display ratio, resolution and model level of each level are shown in Table 1 below.

[0017] Table 1 Display level Display ratio Display model level Data source scale Ground resolution (m / pixel) 11 1:288,895.85 DL1 1:250,000 76.437028 12 1:144,447.93 DL1 1:250,000 38.218514 13 1:72,223.96 DL1 1:50,000 19.109257 14 1:36,111.98 DL1 1:50,000 9.554629 15 1:18,055.99 DL1 1:10,000 4.777314 16 1:9,028.00 DL2 1:10,000 2.388657 17 1:4,514.00 DL2 1:10,000 1.194329 18 1:2,257.00 DL2 1:2,000 or 1:1,000 0.597164 19 1:1,128.50 DL2 1:2,000 or 1:1,000 0.298582 20 1:564.25 DL3 1:1,000 or 1:500 0.149291

[0018] Specifically in this embodiment, in Step 2 above, the process of obtaining the sewage transportation route in the entire urban underground drainage system includes Steps a1 to a4: Step a1: Obtain the pipe points and their accessory facility data of the underground drainage system obtained in the urban underground pipeline census work; among them, the pipe point data of the underground drainage system in the pipe point and their accessory facility data of the underground drainage system includes the attribute information that the pipe point is the starting point or the ending point of the pipeline. Step a2: Obtain the road centerlines in the basic database of the urban electronic map. Step a3: Perform an optimal matching process on the obtained pipe points and their accessory facility data of the urban underground drainage system and the obtained road centerlines to simulate the first- and second-level main pipelines and trunk pipeline routes representing the urban underground drainage system. Step a4: Retrieve the starting point information and ending point information of each pipe point of the obtained underground drainage system, and mark the sewage flow direction in each pipeline of the underground drainage system, forming a transportation route in which the sewage trunk pipeline transports sewage to the sewage main pipeline through the pump station and finally transports the sewage to the sewage treatment plant.

[0019] Specifically, in Step a3 above, the process of performing an optimal matching process on the obtained pipe points and their accessory facility data of the urban underground drainage system and the obtained road centerlines to simulate the first- and second-level main pipelines and trunk pipeline routes representing the urban underground drainage system includes the following Steps b1 to b3: Step b1: Search for all road centerlines in the neighborhood of the set of pipe points to be matched; among them, the set of pipe points to be matched is formed by all the pipe points of the obtained urban underground drainage system. Step b2: Measure the similarity between the connection lines of the pipe points as pipe segments to each candidate road respectively. Step b3: Select the candidate road with the highest similarity as the matching road, and use the center line of this matching road as the generalized linear representation of this pipeline segment.

[0020] It should be noted that in this embodiment, the selection process of the above candidate roads includes the following steps c1 to c3: Step c1: Select the maximum horizontal coordinate and the minimum vertical coordinate among all the pipe point coordinates in the pipe point set, and establish an enclosing rectangle with the selected maximum horizontal coordinate and minimum vertical coordinate as the boundaries. Step c2: Determine the error area: Incorporate the roads around the pipe point set into the area range where the error may exist at the current position; where the area radius of this area range is the maximum value among the distances from the center point of the enclosing rectangle to each pipe point in the pipe point set. Regarding the determined error area situation, see Figure 2 As shown: The radius r of the error area is the maximum value among the distances from the center point O of the enclosing rectangle R to each point in the pipe point set P, that is, r = Max(d1, d2,..., dn), and the set of road segments within the error area formed by the radius r is the candidate road segments.

[0021] Step c3: Use the set of road segments located within this error area as the candidate roads in the pipe point set.

[0022] Furthermore, in the visualization processing method of the urban drainage system based on the pipe network generalization model in this embodiment, the determination process of the above-mentioned matching road includes the following steps d1 to d6: Step d1: Calculate the first node distance, the second node distance, and the vertical distance from the center point of the enclosing rectangle to each candidate road in the pipe point set; where the first node distance of the candidate road is the distance from the center point of the enclosing rectangle to the starting point of the corresponding candidate road, the second node distance of the candidate road is the distance from the center point of the enclosing rectangle to the corresponding candidate road point, and the vertical distance of the candidate road is the distance from the center point of the enclosing rectangle to the foot of the perpendicular from the center point of the enclosing rectangle on the corresponding candidate road. For example, the first node distance from the center point O of the enclosing rectangle to any candidate road in the pipe point set is marked as d m , the second node distance from the center point O of the enclosing rectangle to any candidate road in the pipe point set is marked as d n , and the vertical distance from the center point O of the enclosing rectangle to any candidate road in the pipe point set is marked as d mn ; Step d2: Calculate the included angle between the center line of the enclosing rectangle and each candidate road. Among them, in this embodiment, see Figure 3 As shown, assume that AC and CD are candidate roads, then the distances from the center point O of the enclosing rectangle to these two candidate roads AC and CD are marked as dAC and d CD The included angle between the center line l of the circumscribed rectangle and the candidate road AC is θ AC The included angle between the center line l of the circumscribed rectangle and the candidate road CB is θ CD ; The distance from the center O of the circumscribed rectangle to the first node of the candidate road AC is marked as d A The distance from the center O of the circumscribed rectangle to the second node of the candidate road AC is marked as d c ; The distance from the center O of the circumscribed rectangle to the first node of the candidate road CD is marked as d D The distance from the center O of the circumscribed rectangle to the second node of the candidate road CD is marked as d c ; Step d3, obtain the foot of the perpendicular from the center point of the circumscribed rectangle to each candidate road in the pipe point set; Step d4, make a judgment on whether the foot of the perpendicular is on the candidate road: When the foot of the perpendicular is on the candidate road, take the vertical distance corresponding to the foot of the perpendicular as the distance from the center point of the circumscribed rectangle to the corresponding candidate road, and go to step d5; otherwise, select the minimum distance value from the first node distance and the second node distance, and take the minimum distance value as the distance from the center point of the circumscribed rectangle to the corresponding candidate road, and go to step d5; For example, when the foot of the perpendicular is on the candidate road, take the vertical distance d mn as the distance from the center point of the circumscribed rectangle to the corresponding candidate road; otherwise, take the first node distance d m and the second node distance d n the minimum distance value of is used as the distance from the center point of the circumscribed rectangle to the corresponding candidate road; Step d5, calculate the matching similarity between the pipe point set and the candidate road; among them, the matching similarity calculation method is as follows: s di =U d -λ d ·d i ; s ai =U a -λ a ·d i ; s i = s ai +s di ; λ a +λ d =1; Among them, s i represents the matching similarity between the pipe point set and the candidate road i, sai Denotes the angular matching similarity between the set of pipe points and candidate road i, s di Denotes the distance matching similarity between the set of pipe points and candidate road i, U a Denotes the maximum included angle between the center line of the circumscribed rectangle and all candidate roads, U d Denotes the maximum distance from the center point of the circumscribed rectangle to all candidate roads, λ a Denotes the weight of the distance, λ d Denotes the weight of the included angle; Among them, if the included angle between any road segment and the center line of the circumscribed rectangle exceeds U a Or the distance between any road segment and the center point of the circumscribed rectangle exceeds U d , it is determined that there is no similarity between any road segment and the set of pipe points, and this road segment is deleted from the candidate roads; Step d6, taking the candidate road corresponding to the matching similarity with the maximum matching similarity value as the matching road segment.

[0023] In addition, according to actual needs, in this embodiment, the visualization processing method of the urban drainage system based on the pipe network generalization model can also be based on the urban underground drainage pipe network census database to perform drainage facility data collection and classification and reorganization; and, according to the whole process of sewage generation, collection, transportation, treatment and discharge, perform spatial positioning coding on the drainage pipe network topological model.

[0024] Specifically, the spatial positioning coding process here is as follows: The drainage facilities are divided into 5 basic categories: drainage households, pipe networks (sewage pipe networks, rainwater pipe networks, combined sewer pipe networks), pump stations (sewage pump stations, rainwater pump stations), sewage treatment plants and drainage outlets (in-river (sea) sewage outfalls, in-river (sea) drainage outlets); Assign a unique code to each drainage facility based on a preset coding rule; among them, the unique code uses an 18-bit character coding, which consists of 8-bit spatial positioning codes, 6-bit facility classification codes and 4-bit sequence codes from left to right. For example, in this embodiment, the spatial positioning coding is as follows: (1) The spatial positioning code is 8 digits of the 1:500 map sheet number of the census unit where the pipeline is located; (2) The 6-bit facility classification code is divided into 2-bit category codes, 2-bit "source-network-plant-outlet" major category codes, and 2-bit minor category codes; for example, WS is the "sewage" category code, 02 is the "sewage pipe network" major category code, and 03 is the "sewage pipe" minor category code; (3) The 4-bit pipe segment sequence code is numbered in sequence for the pipe segment and its affiliated drainage facilities according to the orientation. For the east-west direction, it is numbered from west to east, and for the north-south direction, it is numbered from north to south. The value range is 0001-9999.

[0025] Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations can be made to the present invention for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A visualization processing method for urban drainage systems based on a generalized pipe network model, characterized in that, It includes the following steps: Step 1: Construct a drainage system framework model that represents the overall spatial distribution pattern of the entire urban drainage system. Among them, the drainage system framework model takes the sewage treatment plant as the main node, the pumping stations that transport sewage to the sewage treatment plant as the backbone nodes, and the connections between the sewage treatment plant and each pumping station and between the pumping stations to schematically outline the drainage system line framework, thereby characterizing the sewage flow relationship characteristics within the entire system; Step 2: On the basis of the constructed drainage system framework model, construct a generalized drainage system model that reflects the upstream and downstream topological relationships between the sewage treatment plant and the drainage pumping stations and the relationship between the main pipelines and the trunk pipelines that are interconnected. Among them, the generalized drainage system model represents the sewage conveyance route within the entire urban underground drainage system; Step 3: Simplify the constructed generalized drainage system model, and retain all the main pipelines that can reflect the layout of the urban underground sewage system and the sewage flow direction, and use the topological relationship formed by all the retained main pipelines as the drainage system topological model; Step 4: On the basis of the obtained drainage system topological model, use two geometric forms of points and lines to make a schematic physical expression of the pipe network relationship in the drainage system topological model, so as to realize the visual display of the urban underground drainage system.

2. The visualization processing method of the urban drainage system based on the pipe network generalization model according to claim 1, characterized in that In Step 2, the process of obtaining the sewage conveyance route within the entire urban underground drainage system includes: Step a1: Obtain the underground drainage system pipe points and their affiliated facility data obtained in the urban underground pipeline census work. Among them, the underground drainage system pipe point data in the underground drainage system pipe points and their affiliated facility data includes the attribute information that the pipe point is the starting point or the ending point of the pipeline; Step a2: Obtain the road centerlines in the urban electronic map basic database; Step a3: Perform an optimal matching process on the obtained urban underground drainage system pipe points and their affiliated facility data and the obtained road centerlines to simulate the first- and second-level main pipelines and trunk pipeline routes that represent the urban underground drainage system; Step a4: Retrieve the starting point information and ending point information of each pipe point in the obtained underground drainage system, and mark the sewage flow direction in each pipeline of the underground drainage system, forming a conveyance route in which the sewage trunk pipelines transport sewage to the sewage main pipelines through the pumping stations and finally transport the sewage to the sewage treatment plant.

3. The visualization processing method for urban drainage systems based on the pipe network generalization model according to claim 2, wherein In Step a3, the process of performing an optimal matching process on the obtained urban underground drainage system pipe points and their affiliated facility data and the obtained road centerlines to simulate the first- and second-level main pipelines and trunk pipeline routes that represent the urban underground drainage system includes the following steps: Step b1: Search for all road centerlines within the neighborhood of the set of pipe points to be matched. Among them, the set of pipe points to be matched is formed by all the pipe points of the obtained urban underground drainage system; Step b2: Measure the similarity between the pipe point connection lines as pipe segments and each candidate road respectively; Step b3: Take the candidate road with the maximum similarity as the matching road, and take the road centerline of the matching road as the generalized linear expression of this pipe segment.

4. The visualization processing method for urban drainage systems based on the pipe network generalization model according to claim 3, characterized in that The process of selecting the candidate road includes the following steps: Step c1: Select the maximum horizontal coordinate and the minimum vertical coordinate among all the pipe point coordinates in the pipe point set, and establish an enclosing rectangle with the selected maximum horizontal coordinate and minimum vertical coordinate as the boundaries. Step c2: Determine the error area: Incorporate the roads around the pipe point set into the area range where the current position error may exist; among them, the area radius of this area range is the maximum value among the distances from the center point of the enclosing rectangle to each pipe point in the pipe point set. Step c3: Use the road segment set located within this error area as the candidate roads in the pipe point set.

5. The visualization processing method for urban drainage systems based on a pipe network generalization model according to claim 4, wherein, It also includes: Based on the urban underground drainage pipe network census database, perform data collection and classification and recombination of drainage facilities. And, according to the whole process of sewage generation, collection, transportation, treatment and discharge, perform spatial positioning coding on the drainage pipe network topological model.

6. The visualization processing method of the urban drainage system based on the pipe network generalization model according to claim 5, characterized in that The process of the spatial positioning coding is as follows: Classify the drainage facilities into 5 basic categories: drainage households, pipe networks, pumping stations, sewage treatment plants and drainage outlets. Assign a unique code to each drainage facility based on a preset coding rule; among them, this unique code uses an 18-bit character coding, which consists of 8-bit spatial positioning codes, 6-bit facility classification codes and 4-bit sequence codes from left to right in sequence.

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