Automatic Simplification Method for Drainage Networks with Data Protection Function

Abstract

This invention provides an automatic simplification method for drainage pipe networks with data protection capabilities, comprising: Step 1: Pipeline network data preparation: describing the drainage pipe network using an abstract network composed of nodes and pipelines, and obtaining the topological structure and related basic information of the nodes and pipelines; Step 2: Adding simplified feature fields and establishing a mechanism for the coexistence of simplified pipe network data and original pipe network data; Step 3: Entering simplified feature field values ​​into a GIS database; Step 4: Designing an automatic simplification algorithm for the drainage pipe network to complete the automatic simplification of the drainage pipe network while protecting the original data. The algorithm structure of this invention is clear, requires no user intervention during the simplification process, and can simplify to the user-specified precision. By establishing a mechanism for the coexistence of simplified and original pipe network data, the simplification of the pipe network is achieved while protecting the original data.

Description

Technical Field

[0001] This invention relates to the field of GIS technology for urban drainage pipe networks, and in particular, to an automatic simplification method for drainage pipe networks with data protection functions. Background Technology

[0002] To improve the management efficiency and level of urban drainage networks, Geographic Information Systems (GIS), with their powerful data management functions and spatial analysis characteristics, have been more widely and deeply applied in the intelligent and information-based construction of urban drainage systems. Data is the core and foundation of GIS. For various applications in smart water management, such as hydraulic modeling, asset management, and statistical analysis, drainage network GIS data needs to comprehensively reflect the various attributes of the drainage network and possess the highest data completeness. However, due to the excessively high level of detail in the original drainage network GIS data, large-area hydraulic modeling of drainage networks will face problems such as data redundancy, high model complexity, and excessively long simulation times. Therefore, it is essential to appropriately simplify the network data without compromising the accuracy of the model simulation.

[0003] Currently, there are two main methods for simplifying drainage pipe networks: pipe segment cutting and pipe segment merging. Pipe segment cutting involves setting a pipe diameter threshold to delete some pipe segments with diameters smaller than that threshold, while retaining the main pipe network structure. Pipe segment merging, under constraints such as the maximum allowable pipe length, combines multiple series pipe segments with the same properties into one pipe segment.

[0004] The aforementioned methods for simplifying drainage pipe networks all rely on manual intervention to some extent in practice, resulting in low efficiency and high error rates. Furthermore, they fail to consider data protection for the original pipe network. These methods achieve simplification by deleting parts of the original data and reconstructing the topological relationships of pipe segments and nodes. Data backup is required for each simplification process, and simplification is then performed on the backup data, making it impossible to manage the original GIS data and the pipe network model data uniformly. With rapid urban development, the discrepancies between GIS data and model data gradually increase, ultimately leading to the failure of the pipe network model.

[0005] The following issues urgently need to be addressed in existing drainage network simplification technologies:

[0006] 1. When simplifying data by deleting some original data and reconstructing the topology of pipe segment nodes, it is necessary to back up the data. Simplifying the pipe network based on the backup data makes it impossible to manage the original GIS data and the pipe network model data in a unified manner.

[0007] 2. To a certain extent, relying on manual simplification of drainage network data leads to problems of low efficiency and high error rate. Summary of the Invention

[0008] The purpose of this invention is to provide an automatic simplification method for drainage pipe networks with data protection functions, so as to solve the technical problem that GIS data and simplified pipe network model data cannot be managed in a unified manner when automatically simplifying large-scale and complex actual drainage pipe networks.

[0009] To achieve the above objectives, the present invention provides an automatic simplification method for drainage pipe networks with data protection functions, comprising:

[0010] Step 1: Pipeline network data preparation: Describe the drainage pipeline network using an abstract network composed of nodes and pipelines, and obtain the topology and related basic information of the nodes and pipelines;

[0011] Step 2: Add simplified feature fields to establish a mechanism for the coexistence of simplified pipeline network data and original pipeline network data;

[0012] Step 3: Enter simplified feature field values ​​into the GIS database;

[0013] Step 4: Design an automatic simplification algorithm for drainage pipe networks to complete the automatic simplification of drainage pipe networks while protecting the original data;

[0014] Step four specifically includes the protection of key data during the simplification process, the processing of the catchment area, the trimming of branched pipes, and the merging of series pipe segments with the same properties.

[0015] Preferably, in step one, the basic information includes:

[0016] (A) Basic information related to node objects: Specifically, it includes node identifier, node type, out-degree, in-degree, upstream pipeline identifier, and downstream pipeline identifier;

[0017] (B) Basic information related to pipeline objects: Specifically, it includes pipeline identification code, pipeline type, start node identification code, end node identification code, pipe length, cross-sectional geometric parameters, and flow direction.

[0018] Preferably, the specific method of step two is as follows: expand the pipeline network elements with appropriate simplified feature fields in the GIS database to store the simplified status and topology information of the simplified pipeline network elements; wherein the simplified feature fields of node objects include a simplified identifier; the simplified feature fields of pipeline objects include a simplified identifier, a simplified termination node identifier code, a simplified pipe length, and a subordinate retained pipe segment identifier code.

[0019] Preferably, in step four, the protection of key data during the simplification process is specifically achieved by classifying nodes and pipelines in the pipeline network into protected elements and ordinary elements according to their different functions. Protected elements are always retained during the simplification process.

[0020] Preferably, in step four, the processing of the catchment area involves the following: for a node that serves as the runoff receiving point of the catchment area, if its simplified status is "deleted", then the runoff receiving point of its associated catchment area will be transferred to the termination node of the downstream pipeline it connects to.

[0021] Preferably, the specific method for pruning the branched tubes in step four is as follows:

[0022] (4-A-1) Identify the initial branching pipe segment metasystem in the pipeline network (the pipe segment metasystem consists of a pipe segment L1, an initial node N1, and an initial node N2), forming a set S. DP It also records relevant information for each metasystem, including node and pipeline identifiers and related attribute parameters;

[0023] (4-A-2) Identify the trimmable starting branched tube segment system;

[0024] (4-A-3) Calculate the attribute parameters in the trimmable starting branch segment metasystem;

[0025] (4-A-4) Update the initial branch segment metasystem set S DP ;

[0026] (4-A-5) Determine whether the pipeline network meets the simplification accuracy requirements. If it does, end the process. If it does not, return to step (4-A-2) to continue simplification.

[0027] Preferably, in step four, the specific method for merging series pipe segments with the same properties is as follows:

[0028] (4-B-1) Establish a storage queue and perform initialization;

[0029] (4-B-2) Enqueue the starting node;

[0030] (4-B-3) Determine if the queue is empty. If yes, end the process. Otherwise, visit the head node of the queue and set it to the visited state.

[0031] (4-B-4) Determine whether there is a series pipe segment subsystem. If yes, the series pipe segment subsystem satisfies the merging requirement and proceed to step (4-B-5). Otherwise, proceed directly to step (4-B-6).

[0032] (4-B-5) Calculate the attribute parameters in the series pipe segment element system, and proceed to step (4-B-6);

[0033] (4-B-6) Determine if there are any unvisited adjacent nodes. If yes, proceed to step (4-B-7); otherwise, proceed directly to step (4-B-8).

[0034] (4-B-7) Enqueue adjacent nodes and proceed to step (4-B-8);

[0035] (4-B-8) Pop the head node and return to step (4-B-3) to continue simplifying until all nodes are in the visited state.

[0036] The present invention has the following beneficial effects:

[0037] 1. The algorithm has a clear structure, is easy to convert into a programming language, and can adapt to drainage pipe networks of various topologies and complexities. No user intervention is required during the simplification process, and it can be simplified to the user-specified precision.

[0038] 2. By establishing a mechanism that integrates simplified pipeline network data with original pipeline network data, the simplification of the pipeline network can be achieved while protecting the original data. This allows the drainage pipeline network GIS data to provide pipeline network topology structures of different levels of detail for different application scenarios, ensuring that the data required for various application scenarios (such as drainage pipeline network hydraulic models) are closely embedded in the GIS data, thus guaranteeing data timeliness.

[0039] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0040] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0041] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0042] Figure 2 This is a flowchart of the branch tube trimming process.

[0043] Figure 3 This is a schematic diagram of branch tube cutting.

[0044] Figure 4 A simplified flowchart for merging series pipe sections.

[0045] Figure 5 This is a simplified schematic diagram of merging series pipe sections.

[0046] Figure 6 This is a topology diagram of the original drainage network in an application example.

[0047] Figure 7 This is a simplified flowchart of a drainage network for an application example.

[0048] Figure 8 A simplified topology diagram of the drainage network is provided for the application examples. Detailed Implementation

[0049] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0050] Step 1: Pipeline Data Preparation

[0051] An abstract network composed of nodes and pipelines is used to describe the drainage pipe network. Each element in the drainage pipe network is mapped to a node or pipeline in the abstract network, and the topology and basic attribute parameters of the pipe network elements are obtained. The correspondence and the attribute parameters required by the method in this paper are shown in Table 1. Furthermore, the degree of a node is defined as the number of connections to that node, with the in-degree being the number of connections starting from and ending at a given node, and denoted by δ. + This means that the number of connections originating from and ending at a certain node is the out-degree, and δ represents the number of connections ending at that node. - express.

[0052] Table 1. Correspondence and related attributes between drainage pipe network and abstract network.

[0053]

[0054]

[0055] Note: Since some node objects (inspection wells, rainwater inlets) have a topological inclusion relationship with the surface catchment area, the runoff generated by each catchment area flows into the drainage network through the node, so it is also necessary to obtain the relevant information of the catchment area.

[0056] Step 2: Establish a mechanism for the coexistence of simplified pipeline network data and original pipeline network data.

[0057] To achieve automatic simplification of drainage networks while protecting the original data, a reasonable database structure needs to be designed to store both the original and simplified network states using a single set of GIS data. Therefore, the basic attributes of the network GIS database need to be expanded with simplified feature attribute fields, as shown in Table 2, to store the simplified state and topology information of the simplified network elements.

[0058] Table 2 Simplified Feature Field Information

[0059]

[0060] Step 3: Enter the values ​​of each field from Step 2 into the GIS database.

[0061] Specifically, the initial values ​​of the SplStateNode and SeqNumber fields are both set to 1 (reserved), and the initial values ​​of the SplTnode, SplLength, Ownerlink, and SplNodeIndex fields correspond to the parameter values ​​of LmDNn, LmLE, Lm, and SxNn, respectively.

[0062] Step 4: Design of an automatic simplification algorithm for drainage pipe networks

[0063] 1. Protection of critical data during the simplification process:

[0064] Because different types of nodes and pipelines have varying importance in the pipeline network, key nodes and pipelines need to be protected during network simplification to prevent important network information from being lost during the simplification process. Therefore, nodes and pipelines are divided into protected elements and ordinary elements according to their different functions, as shown in Table 3. Protected network elements are always retained during the simplification process.

[0065] Table 3. Classification of Pipeline Network Elements

[0066]

[0067] 2. Treatment of water catchment area:

[0068] In order to ensure that the runoff generated by the catchment area can flow into the drainage network through the relevant nodes in the simplified network data, if the simplified status of a node that serves as the runoff receiving point of the catchment area is "deleted", the runoff receiving point of its associated catchment area will be transferred to the terminal node of the downstream pipeline it connects to.

[0069] 3. Branch tube trimming:

[0070] The upstream end of a drainage system often consists of numerous small-diameter outlet pipes and rainwater inlet connection pipes. Including these small-diameter pipes in the model would significantly increase the computational load while having little impact on the calculation results. Branch pipe pruning can greatly reduce this unnecessary computational load. The specific design steps of the branch pipe pruning algorithm are as follows:

[0071] (1) Identify the initial branch pipe segment element system (DL) in the pipeline network and form a set S DP ={DL1, DL2…DL n (n is the number of initial branched pipe segment subsystems). An initial branched pipe segment subsystem consists of an initial branched pipe segment L1, an initial connecting node N1, and an initial connecting node N2. Its mathematical expression is:

[0072] DL={L1,(N1,N2)} Equation (1)

[0073] The initial branched pipe segment element system is the basic object of the branched pipe trimming proposed in this invention. The branched pipe trimming operation reduces the complexity of the pipe network data by removing the initial branched pipe segment element system.

[0074] (2) Determine the trimmable starting branch pipe segment element system. To ensure the practicality of simplified pipe network data, a trimming pipe diameter threshold Dmin needs to be set. This is done by comparing the pipe diameter value L of the starting branch pipe segment L1 in the starting branch pipe segment element system. mC The value of the pipe diameter reduction threshold Dmin is used to determine whether the reduction of the initial branched pipe segment subsystem is appropriate, i.e.:

[0075] If L mC (L1)≤Dmin, so we can use the trimming formula (2).

[0076] If L mC (L1)>Dmin, not suitable for trimming (3)

[0077] The larger the threshold Dmin is, the higher the degree of branch pipe pruning. The threshold should be set according to the application scenario of simplifying pipeline network data.

[0078] (3) Calculate the attribute parameters of the trimmable starting branch segment element system. If a certain starting branch element system can be trimmed, i.e., according to equation (2), then the values ​​of the SplStateNode(N1) and SeqNumber(L1) fields are updated to 0 (deleted), N nδ + (N2) parameter value decreased by 1;

[0079] (4) Update the initial branch segment metasystem set S DP Remove S DP The cut-off initial branch pipe segment element system is added to the newly added initial branch pipe segment element system in the cut-off pipe network.

[0080] (5) The process ends once the pipeline meets the simplification accuracy requirements; otherwise, return to step (2) and continue simplification.

[0081] 4. Merging of Series Pipe Segments with the Same Attribute: After the initial branched pipe segment metasystem is pruned, many series pipe segments with the same flow direction and attributes will be formed in the pipe network. These segments can be appropriately merged to ensure the accuracy of the model simulation while reducing model complexity and improving hydraulic simulation efficiency. The simplified operation for merging series pipe segments with the same attribute is to retain the upstream pipe segment L1 of the common node N1, and the downstream pipe segment L2 as a subordinate segment of the retained pipe segment L1. The attribute parameters of the upstream pipe segment L1, including pipe length and termination node identifier, are updated to replace the original series pipe segments L1, L2, and the common node N1. For ease of explanation, it is assumed here that pipe segments L1 and L2 satisfy the merging condition.

[0082] Based on the breadth-first search algorithm for graphs, this paper describes the merging process of series pipe segments with the same flow direction and attributes. A queue data structure is used to implement the breadth-first traversal of the pipe network nodes. During the traversal, the starting node of the pipe network is used as the initial node, and the process searches for adjacent downstream nodes in a forward direction, progressing layer by layer. By identifying the series pipe segment metasystem (SL), and using the user-specified maximum allowable pipe length (Lmax) as the merging threshold, the paper checks whether the upstream and downstream pipelines of the traversed nodes meet the merging conditions. If they do, the merging operation is performed, and the node is dequeued, thus simplifying the pipe network.

[0083] The specific design steps of the algorithm for merging series pipe segments with the same properties are as follows:

[0084] (1) Create a storage queue (Queue) and perform initialization.

[0085] (2) Enqueue the starting node. Further, find the starting node in the pipeline network as the starting node and add it to the queue in sequence.

[0086] (3) Set the loop termination condition "the queue is empty".

[0087] (4) If the queue is not empty, visit the head node (V) and set it to visited state. If the queue is empty, end the merge.

[0088] (5) Identify the series pipe segment subsystem SL. Further, determine whether the current node and its connecting pipes can form a series pipe segment subsystem. A series pipe segment subsystem consists of two series pipe segments L1 and L2 of the same attribute, connecting nodes N1 and N2 at both ends, and an intermediate node N3. Its mathematical expression is:

[0089] SL={(L1,L1),N3,(N1,N2)} Formula (4)

[0090] The cross-sectional geometric parameters, flow direction, and type of the series pipe segments L1 and L2 are consistent, and the in-degree and out-degree values ​​of the common node N3 are all 1. Furthermore, L1, L2, and N3 all belong to the common elements listed in Table 3. The series pipe element system is the basic object of the series pipe merging proposed in this invention.

[0091] (6) Determine whether the series pipe segment subsystem can be merged. To ensure the practicality of simplified pipeline network data, a maximum allowable merged pipe length Lmax needs to be set. This is done by comparing the pipe lengths L1 and L2 of the series pipe segment subsystem. mLE The sum of the values ​​and the maximum permissible combined pipe length Lmax are used to determine whether the merging of the series pipe segment subsystems is permitted.

[0092] If L mLE (L1)+L mLE(L2)≤Lmax, satisfying the combined equation (5).

[0093] If L mLE (L1)+L mLE (L2)>Lmax, therefore the merge equation (6) is not satisfied.

[0094] Regarding the setting of the maximum allowable merged pipe length, the larger the Lmax is, the higher the degree of merging of series pipe segments. It should be set accordingly based on the application scenario of simplifying pipeline network data.

[0095] (7) Calculate the original attribute parameters of the pipeline network in the mergeable series pipe segment subsystem. If a certain series pipe segment subsystem can be merged, i.e., according to equation (5), then the value of the SplStateNode(N1) field is updated to 0 (deleted), and the value of the SeqNumber(L2) field is updated to 2 (subordinate sequence number). The values ​​of the SplLength(L1) and SplTnode(L1) fields are determined as follows:

[0096] SplLength(L1)=L mLE (L1)+L mLE (L2) Equation (7)

[0097] SplTnode(L1) = L mDNn (L2) Equation (8)

[0098] (8) Dequeue the head node V, traverse the adjacent nodes U of node V, and enqueue U if the adjacent node U is not marked as visited.

[0099] (9) Return to (4) and continue to simplify until all nodes are in the visited state.

[0100] Application Examples

[0101] like Figure 1 The diagram shows a flowchart of an automatic simplification method for drainage pipe networks with data protection function provided by the present invention. This method enables automatic simplification of drainage pipe network GIS data while protecting the original data. It mainly includes the following steps:

[0102] Step 1: Data Preparation; Describe the drainage network using an abstract network composed of nodes and pipelines, and obtain the topology and related basic information of the nodes and pipelines. The basic information of the node objects includes node identifier, node type, out-degree, in-degree, upstream pipeline identifier, and downstream pipeline identifier. The basic information of the pipeline objects includes pipeline identifier, pipeline type, starting node identifier, ending node identifier, pipe length, cross-sectional geometric parameters, and flow direction.

[0103] Step Two: Establishing a Mechanism for the Coexistence of Simplified and Original Pipeline Data: In the GIS database, appropriate simplified feature fields are added to the pipeline elements of the example to store the simplified status and topology information of the simplified pipeline elements. The simplified feature fields for node objects include a simplified identifier; the simplified feature fields for pipeline objects include a simplified identifier, a simplified termination node identifier, a simplified pipe length, and a subordinate retained pipe segment identifier.

[0104] Step 3: Enter simplified feature field values ​​into the GIS database.

[0105] Step 4: Automatic Simplification of Drainage Pipe Network. The pipe network simplification method designed in this invention mainly involves cutting branched pipes and merging series pipe sections of the same attribute. When simplifying drainage pipe networks, especially large drainage pipe networks, it is difficult to achieve the expected simplification requirements using only one simplification method. Therefore, two methods are often used in combination to achieve the desired simplification effect.

[0106] Branch pipe trimming: This addresses situations where multiple branch pipe segments exist within a real-world pipe network, such as... Figure 2 As shown in (a). The present invention is simplified by the following specific implementation steps, see [reference]. Figure 3 .

[0107] Step (1): Identify the initial branched pipe segment subsystem in the pipeline network and form a set S DP ={DL1, DL2…DL n}(n is the number of initial branch pipe segment subsystems, DL is the mathematical expression of the initial branch pipe segment subsystem, i.e., DL={L1,(N1,N2)}, L1 is an initial branch pipe segment in DL, N1 is the initial connection node of L1, and N2 is the terminal connection node of L1), and records the relevant information of each subsystem, including the identification codes of nodes and pipelines and related attribute parameters (such as node type, pipeline type, and pipeline cross-sectional set parameters). For Figure 2 In example (a), three initial branched tube segment subsystems can be identified, and S DL ={DL1, DL2, DL3}, according to equation (1), they are respectively: DL1 = {L1, (N1, N2)}, DL2 = {L2, (N5, N2)}, DL3 = {L5, (N6, N3)}.

[0108] Step (2): Determine the trimmable starting branch pipe segment subsystem. Set the trimming pipe diameter threshold Dmin, and determine whether the corresponding starting branch pipe segment subsystem is suitable for trimming according to equations (2) and (3).

[0109] Step (3): Calculate the attribute parameters of the trimmable starting branch segment metasystem. If a certain starting branch metasystem can be trimmed, i.e., according to equation (2), then the values ​​of the SplStateNode(N1) and SeqNumber(L1) fields are updated to 0 (deleted), N nδ + (N2) parameter value decreased by 1;

[0110] Step (4): Update the initial branched tube segment metasystem set S DP Remove S DP The pruned initial branch pipe segment element system is added to the pruned pipe network, along with newly added initial branch pipe segment element systems. For example... Figure 2 As shown in (b), remove S DL In the metasystems DL1, DL2, and DL3, the removal of pipe segment L1 and node N1 in metasystem DL1, and the removal of pipe segment L2 and node N5 in metasystem DL2, leads to the generation of a new starting branch pipe segment metasystem DL4 = {L3, (N2, N3)}.

[0111] Step (5): The process ends when the pipeline meets the simplification accuracy requirements; otherwise, return to step (2) and continue simplification.

[0112] Merging series pipe segments of the same attribute: This is for situations where multiple series pipe segments exist in an actual pipe network, such as... Figure 4 As shown in (a). The present invention is simplified by the following specific implementation steps, see [reference]. Figure 5 .

[0113] Step (1) Create a storage queue (Queue) and perform initialization.

[0114] Step (2) Enqueue the starting node. Further, enqueue the starting node N1.

[0115] Step (3) Set the loop termination condition "the queue is empty".

[0116] Step (4) Access the head node N1 and set it to the accessed state.

[0117] Step (5) Identify the series pipe segment subsystem SL. The series pipe segment subsystem consists of two series pipe segments L1 and L2 of the same attribute, connecting nodes N1 and N2 at both ends, and an intermediate node N3. Its mathematical expression is:

[0118] SL={(L1,L2),N3,(N1,N2)} Formula (4)

[0119] In the formula, the cross-sectional geometric parameters, flow direction, and type of the series pipe segments L1 and L2 are consistent, the in-degree and out-degree values ​​of the common node N3 are all 1, and L1, L2, and N3 are all ordinary elements. The series pipe element system is the basic object of the series pipe merging proposed in this invention. For Figure 4 In example (a), it is clear that the serial pipe segment metasystems SL1 = {(L1,L2),N2,(N1,N3)} and SL2 = {(L1,L3),N3,(N1,N4)} can only be identified when traversing to nodes N2 and N3.

[0120] Step (5) Determine whether the series pipe segment subsystems can be merged. Set the maximum allowable merged pipe length Lmax, and determine whether the merging of the series pipe segment subsystems meets the conditions according to equations (5) and (6).

[0121] Step (6): If equation (5) holds, update the relevant attribute information of the network elements in the mergeable series pipe segment element system. For example... Figure 4 As shown in (b), in the merging operation, pipe segment L2 in the series pipe segment metasystem SL1 is merged into pipe segment L1, becoming one of its subordinate pipe segments. That is, the retained pipe segment L1 replaces the pipe segments L1, L2, and common node N2 before merging. To achieve the above objective, it is necessary to update the relevant attribute information of pipe segments L1, L2, and common node N2, such as: updating the SplStateNode(N1) field value to 0 (deletion), updating the SeqNumber(L2) field value to 2 (subordinate sequence number), updating the SplLength(L1) field value according to equation (7), and updating the SplTnode(L1) field value according to equation (8). Figure 4 (c)

[0122] Step (7) Dequeue the head node V, traverse the adjacent nodes U of node V, and enqueue U if the adjacent node U is not marked as visited.

[0123] Step (8) returns to step (5) and continues to simplify.

[0124] Figure 6 The diagram illustrates the topology of a drainage network. The prefix "J" represents a manhole node, "Out" represents a discharge outlet node, numbers represent connecting pipe segments, and arrows indicate the drainage flow direction. As shown, this drainage network has 16 manhole nodes, 1 discharge outlet node, and 16 connecting pipe segments.

[0125] Table 4 shows detailed information on all connecting pipe segments in the example network before simplification.

[0126] Table 4 Information table before simplification of connecting pipe sections

[0127]

[0128] The above-described simplification methods can achieve automatic simplification of the pipeline network while protecting data, thus achieving the desired simplification effect. Figure 7 A simplified flowchart of the pipeline network is shown below, resulting in the simplified pipeline network topology. Figure 8 As shown, where Figure 8 (a) shows the simplified pipe network after removing the branched tubes. Figure 8 (b) shows the simplified pipe network after merging series pipe segments. The data accuracy of the simplified pipe network can be adjusted according to the actual application requirements of the pipe network. When the simplified pipe network data is used for planning analysis, a larger D value can be set. min and L max The value is then simplified multiple times to obtain a more simplified application network. However, when the simplified network data is used for statistical analysis, fault detection, or other scenarios requiring high simulation accuracy, a smaller D value should be set. min and L max The goal is to preserve the elemental characteristics of the original system as much as possible in the simplified pipeline network data.

[0129] The process of pruning the branched pipe is shown in Table 5. The pruning pipe diameter threshold Dmin is set to 300mm. For example, in the 4th pruning operation, the starting pipe segment 11 and the starting node J13 are pruned, and the values ​​of the SplStateNode(J13) and SeqNumber(11) fields are updated to 0 (deleted).

[0130] Table 5. Procedure for branched tube trimming

[0131]

[0132]

[0133] The specific process of merging series pipe segments is shown in Table 6, where the maximum allowable merged pipe length Lmax = 50m is set. Starting from the initial nodes J15, J10, J6, and J3, the segments are sequentially enqueued and traversed in the order J15→J10→J6→J3→J14→J9→J5→J2→J12→J8→J4→J1→Out1. The series pipe segment metasystem is identified to determine if merging is feasible, and then the merging operation is executed. For example, in the first merging operation, series pipe segments 14 and 15 are merged, with upstream segment 15 retained and downstream segment 14 becoming a subordinate segment of segment 15. According to the simplified method proposed by this invention, simplified pipe network data and original pipe network data can coexist in a single set of pipe network GIS data. Conventional simplification methods, however, sacrifice the precision of the original pipe network data, resulting in simplified pipe network data not being updated in real-time with the original GIS data.

[0134] Table 6. Procedure for Merging Series Pipe Segments

[0135]

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sewer network automatic simplification method with data protection function, characterized in that, The method comprises the following steps: Step 1: pipe network data preparation: an abstract network composed of nodes and pipelines is used to describe the drainage pipe network, and the topological structure and related basic information of the nodes and pipelines are obtained; Step 2: adding simplified feature fields to establish a mechanism for coexistence of simplified pipe network data and original pipe network data; Step 3: entering the simplified feature field values in the GIS database; Step 4: designing an automatic simplification algorithm for the drainage pipe network to complete the automatic simplification of the drainage pipe network while protecting the original data; wherein Step 4 specifically comprises protection of key data in the simplification process, processing of sub-area of catchment, pruning of dendritic pipes, and merging of pipes with the same attribute in series. The specific method for protecting key data in the simplification process is as follows: the nodes and pipelines in the pipe network are divided into protected elements and ordinary elements according to their different roles, and the protected elements are always in a reserved state in the simplification process. The specific method for processing the sub-area of catchment is as follows: if the node serving as the runoff receiving point of the sub-area of catchment is in a state of "deletion" after simplification, the runoff receiving point of the associated sub-area of catchment will be transferred to the terminal node of the downstream pipeline connected to the node. The specific method for pruning dendritic pipes is as follows: (4-A-1) identifying the starting dendritic pipe segment element system in the pipe network to form a set SDP, and recording the relevant information of each element system, including the identification codes of nodes and pipelines and related attribute parameters; (4-A-2) determining the dendritic pipe segment element system that can be pruned; (4-A-3) calculating the attribute parameters of the dendritic pipe segment element system that can be pruned; (4-A-4) updating the starting dendritic pipe element system set SDP; (4-A-5) judging whether the pipe network meets the simplification accuracy requirement, and if yes, ending, and if not, returning to step (4-A-2) for continuous simplification. The specific method for merging pipes with the same attribute in series is as follows: (4-B-1) establishing a storage queue and performing initialization processing; (4-B-2) starting node enqueuing; (4-B-3) judging whether the queue is empty, and if yes, ending, and if not, accessing the head node and setting the visited state; (4-B-4) judging whether there is a series pipe segment element system, and if yes, the series pipe segment element system meets the merging, and entering step (4-B-5), and if not, directly entering step (4-B-6); (4-B-5) calculating the attribute parameters of the series pipe segment element system, and entering step (4-B-6); (4-B-6) judging whether there is an unvisited adjacent node, and if yes, entering step (4-B-7), and if not, directly entering step (4-B-8); (4-B-7) adjacent node enqueuing, and entering step (4-B-8); (4-B-8) head node dequeuing, and returning to step (4-B-3) for continuous simplification until all nodes are in the visited state.

2. The method of claim 1, wherein, In Step 1, the basic information comprises: (A) node class object related basic information: specifically comprising node identification code, node type, out-degree, in-degree, upstream pipeline identification code, and downstream pipeline identification code; (B) pipeline class object related basic information: specifically comprising pipeline identification code, pipeline type, starting node identification code, terminal node identification code, pipe length, cross-section geometric parameters, and flow direction.

3. The method of claim 1, wherein, The specific method of step two is: expanding appropriate simplified feature fields in the GIS database for the pipe network elements to store the simplified state and topological information of the simplified pipe network elements; the node class object simplified feature field includes a simplified identification; the pipe line class object simplified feature field includes a simplified identification, a simplified terminal node identification code, a simplified pipe length, and a dependent reserved pipe section identification code.

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