Urban community surface ponding simulation method and system considering roof structure

Abstract

The invention discloses an urban community surface ponding simulation method and system considering a roof structure, and aims to solve the problem that an existing ponding simulation method does not consider the influence of a building roof on ponding formation, and the method comprises the following steps: collecting multi-angle photo data to construct an oblique photography model and a digital surface model; roof data are extracted from the digital surface model, and roof types are divided into flat roofs and sloping roofs; according to the characteristics of a flat roof and a slope roof, a flat roof drainage structure and a slope roof drainage structure are constructed respectively, and then a roof drainage model considering the roof type is constructed; integrating the roof drainage model and the urban community hydrological model considering the roof, and operating the urban community hydrological model to simulate urban community surface ponding; on the basis of actual drainage conditions of different roof types, drainage structures suitable for flat roofs and slope roofs are arranged, the influence of roof structures on urban ponding is effectively simulated, and more accurate urban surface ponding simulation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of water accumulation simulation, and in particular to a method and system for simulating ground water accumulation in urban communities taking into account roof structures. Background Art

[0002] Researchers use urban hydrological models based on urban hydrological physical processes to scientifically and effectively deal with urban waterlogging problems. With the development of technology, the simulation of urban hydrological processes has expanded from one-dimensional models to one- and two-dimensional coupled models. The one- and two-dimensional coupled model technology can simulate urban waterlogging in complex urban geographical environments; most existing urban waterlogging models use data with low accuracy and therefore cannot meet the requirements for the prevention and control of urban waterlogging problems. Most existing urban waterlogging models also ignore the important role of building roofs in the formation of waterlogging, especially the unique role of different types of roofs in this process.

[0003] Most waterlogging simulation methods, such as the Chinese patent with publication number CN114692432A, have certain limitations in data accuracy and model complexity. These methods usually rely on low-precision meteorological data, terrain information, and land use data, which limits the accuracy of model predictions. In addition, the model ignores the impact of building roofs on waterlogging during the simulation process, especially the differences in rainwater management and runoff control between different types of roofs (such as flat roofs and pitched roofs). Such simplification makes the model unable to fully reflect the actual situation, thus affecting the reliability and practicality of the model results. Summary of the invention

[0004] The present invention solves the problem that the existing water accumulation simulation method does not consider the influence of building roofs on the formation of water accumulation, and proposes a method and system for simulating ground water accumulation in urban communities that considers the roof structure. Based on the actual drainage conditions of different roof types, drainage structures suitable for flat roofs and sloping roofs are set to effectively simulate the influence of roof structures on urban water accumulation, so as to achieve more accurate urban ground water accumulation simulation.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a method for simulating ground water in urban communities considering roof structures, comprising the following steps: S1, collect multi-angle photo data to build an oblique photography model and a digital surface model, extract roof data from the digital surface model, and classify roof types into flat roofs and pitched roofs; S2, according to the characteristics of flat roofs and sloping roofs, construct flat roof drainage structures and sloping roof drainage structures respectively, and then construct a roof drainage model considering the roof type; S3, integrate the rooftop drainage model with the urban community hydrological model that takes rooftops into account, and run the urban community hydrological model to simulate ground water accumulation in urban communities.

[0006] In this technical solution, the corresponding roof data is first extracted through oblique photography model data and digital surface data, and the corresponding roof drainage structure is constructed according to the different roof types to establish its roof drainage model; the roof drainage model is integrated with the urban community hydrological model that takes the roof into consideration, and finally the simulation process of urban community area water is realized, realizing the real-time simulation and prediction of urban hydrological processes.

[0007] The present invention is further configured as follows: Step S1 comprises: S11, stitching the multi-angle photos to generate an oblique photography model, and reconstructing a digital surface model through the oblique photography model; S12, separating the ground data of non-building ground data from the digital surface model, extracting the initial roof data, eliminating irrelevant ground objects, and generating roof elevation raster data; S13, the roof types are divided into flat roofs and pitched roofs according to the roof slope to generate classification results.

[0008] In this technical solution, the building roof data is extracted through the created oblique photography model and digital surface, and the roof types are classified into flat roofs and pitched roofs.

[0009] The present invention is further configured as follows: Step S2 comprises: S21, set the drainage node of the flat roof at its geometric center, and use the drainage node as the starting point of the roof drainage pipe; the drainage node and downpipe of the pitched roof are both set at the edge of the roof; S22, setting parameters of drainage nodes and pipes in the flat roof drainage structure and the slope roof drainage structure; S23, based on the results of drainage network structure and parameter setting, a roof drainage model considering the roof type is constructed.

[0010] In this technical solution, according to the characteristics of flat roofs and sloping roofs, flat roof drainage structures and sloping roof drainage structures are constructed respectively, and the set parameters are combined to construct a roof drainage model that takes the roof type into consideration.

[0011] The present invention is further configured as follows: Step S3 comprises: S31, connect the roof drainage nodes with the nodes of the urban drainage network system, input data into the roof drainage model, and combine it with the urban community hydrological model to complete the roof drainage model integration; S32, sequentially constructing a one-dimensional urban community hydrological model and a two-dimensional urban community hydrological model; S33 simulates ground waterlogging in urban communities and generates simulation results, which are raster layers based on waterlogging depth.

[0012] In this technical solution, the main goal is to integrate the urban community hydrological model that takes roofs into account with the roof drainage model, and ultimately achieve the simulation of ground water accumulation in urban communities, so as to accurately assess the water accumulation risk and drainage capacity of urban communities.

[0013] The present invention is further configured as follows: Step S12 comprises: The PMF method is used to extract ground data, and then the ground data of the digital surface model is separated; the initial roof data is extracted according to the characteristics of the ground objects and combined with visual recognition technology, and the initial roof data is output as roof range mask data. According to the roof range mask data, irrelevant ground objects are eliminated to generate roof elevation raster data.

[0014] In this technical solution, after the ground data is extracted by using progressive morphological filtering, it is separated from the digital surface model. After separation, the remaining ground data is used to extract ground feature and further eliminate irrelevant ground objects, so that the roof data can be finally obtained.

[0015] The present invention is further configured as follows: Step S13 includes: S131, traverse the roof elevation grid data pixels, calculate the slope of the roof, and save the calculated slope grid layer; S132, taking slope as a classification feature, selecting SVM training classifier, training samples of flat roofs and sloping roofs, and classifying the roofs of the area after optimizing parameters; S133, converting the classification result into a vector file, and extracting the roof data of the flat roof and the pitched roof according to the vector object range.

[0016] In this technical solution, if the average slope in the area is greater than the set value, it is a pitched roof, and if the average slope in the area is less than the set value, it is a flat roof.

[0017] The present invention is further configured as follows: S23 is specifically: According to the results of drainage network structure and parameter setting, the designed drainage network structure and determined parameter values ​​are input into GIS software, the topological relationship is checked, and the roof drainage model is constructed.

[0018] In this technical solution, this step can eventually build a roof drainage model that takes the roof type into consideration.

[0019] The present invention is further configured as follows: the core equations of the one-dimensional urban community hydrological model are the Manning equation and the Saint-Venant equation, and the core equation of the two-dimensional urban community hydrological model is the shallow water equation.

[0020] In this technical solution, the one-dimensional urban community hydrological model can mainly simulate the water flow dynamics of the urban drainage system, and the two-dimensional urban community hydrological model mainly describes the water flow movement in the horizontal direction.

[0021] The present invention is further configured as follows: before step S31, the following steps are further included: Flat roofs and pitched roofs are divided into watershed areas, and a roof drainage node is marked for each watershed match according to the geographical location of the drainage node that matches the geographical range of the watershed area.

[0022] In this technical solution, after completing the division of the catchment area, a roof drainage node is matched and marked for each catchment area, and then the roof drainage node is connected to the node in the urban drainage network system to ensure that the roof drainage data can accurately flow into the urban drainage hydrological model.

[0023] A system for simulating ground water accumulation in urban communities taking into account roof structures is applicable to the above-mentioned method for simulating ground water accumulation in urban communities taking into account roof structures, comprising: Data extraction module, which extracts roof data through oblique photography model and digital surface model, and classifies roof types into flat roof and pitched roof Model building module, constructs flat roof drainage structure and slope roof drainage structure, and combines drainage network parameters to build a roof drainage model that takes into account roof types; The simulation module integrates the urban community hydrological model and the roof drainage model to simulate ground water accumulation in urban communities.

[0024] The system of this technical solution mainly includes a data extraction module, a model construction module and a simulation module. The data extraction module is connected to the model construction module, and the model construction module is connected to the simulation module. The three perform the above functions in turn to complete the simulation of ground surface water and realize real-time simulation and prediction of urban hydrological processes.

[0025] The present invention can bring the following beneficial effects: The present invention relates to a method for simulating ground water accumulation in urban communities taking into account roof structures. Based on the actual drainage conditions of different roof types, a drainage structure suitable for flat roofs and sloping roofs is proposed to effectively simulate the impact of roof structures on urban water accumulation, so as to achieve more accurate simulation of urban ground water accumulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a method for simulating ground water accumulation in urban communities taking into account roof structures in the present application.

[0027] Figure 2 It is a schematic diagram of the drainage structure involved in a method for simulating ground water accumulation in an urban community taking into account the roof structure of the present application.

[0028] Figure 3 It is a schematic diagram of a roof drainage model involved in a method for simulating ground water accumulation in an urban community taking into account the roof structure of the present application. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] Example 1 This embodiment proposes a method for simulating ground water in urban communities taking into account roof structures. Figure 1 , Figure 2 and Figure 3 , which mainly includes the following steps.

[0031] Step S1, first collect multi-angle photo data, then build an oblique photography model and a digital surface model based on these data, then extract roof data from the data surface model, and classify the roof type into flat roof and pitched roof.

[0032] In more detail, this step mainly includes the following three sub-steps.

[0033] Step S11 , stitching the collected multi-angle photo data to generate an oblique photography model, and then reconstructing a digital surface model through the oblique photography model.

[0034] For the digital surface model, it mainly records the elevation information of the surface and objects, including all natural terrain features and man-made structure features. The model contains the height information of the ground and objects on the ground.

[0035] In this embodiment, the above-mentioned multi-angle photo data is obtained by taking pictures with a drone equipped with multiple cameras at different angles, and the multi-angle photos of the covered area are spliced ​​using oblique photography image processing software to generate an oblique photography model. The oblique photography model can obtain stereoscopic and detailed three-dimensional surface data in the area.

[0036] The digital surface data mentioned above are reconstructed into a digital surface model using GIS software and an oblique photography model.

[0037] Step S12, after completing the reconstruction of the digital surface model, separate the ground data related to non-building ground data in the digital surface model; then extract the initial roof data and remove irrelevant ground objects, and finally obtain the roof elevation grid data.

[0038] This step, in more detail, mainly includes a ground data separation step and a roof data extraction step.

[0039] As for the ground data separation step, it is mainly to extract ground data according to the PMF method, and then separate the ground data of the digital surface model.

[0040] More specifically, the PMF method is a progressive morphological filtering method, which specifically traverses the digital surface model by adjusting the window and distinguishes ground and non-ground data according to the set threshold. The general window size is 5×5 (pixels) and the threshold is 10 meters.

[0041] After using the above-mentioned PMF method, the extracted ground data were checked and then separated from the digital surface model using GIS software.

[0042] For the roof data extraction step, it extracts the initial roof data based on the features of the objects and combines visual recognition technology. Then, the initial roof data is output as roof range mask data. Unrelated objects are eliminated based on the roof range mask data, and finally high-precision building roof elevation raster data is obtained.

[0043] In more detail, after the above-mentioned ground data separation step, the data remaining after the digital surface model is separated is the feature data, which includes buildings, trees and municipal facilities; the visual recognition technology is combined with the feature characteristics (such as color, shape and texture) to perform extraction operations in the GIS software.

[0044] Among them, the main features of the buildings are: the colors of the buildings are mostly dark; the shapes are mostly regular geometric shapes; the textures are regular and have repeated patterns.

[0045] The extracted roof data is output as roof range mask data in the GIS software, and then the roof range mask data is used to eliminate other objects on the basis of the digital terrain model to obtain high-precision building roof elevation raster data.

[0046] Step S13, classifying the roof types into flat roofs and pitched roofs according to the roof slope.

[0047] As for step S13, it mainly includes the following more detailed process.

[0048] Step S131, firstly calculate the slope of the roof, which is specifically to traverse the roof elevation grid data pixels according to the roof calculation formula, and save the calculated slope grid layer.

[0049] In this embodiment, high-precision building roof elevation raster data is used as input to calculate the roof slope in GIS software. The slope calculation method is based on the elevation difference between the center pixel and the eight pixels around it, as follows: , In the above formula, Represents the pixel elevation value of the i-th row and j-th column (m); is the pixel size (m); is the slope; Indicates the rate of change of elevation along the x-axis in the elevation grid data; Indicates the rate of change of elevation along the y-axis in the elevation raster data.

[0050] According to the above three formulas, the building roof elevation grid data pixels are traversed and the calculated slope raster layer is saved.

[0051] Step S132, taking slope as the classification feature, selecting SVM training classifier, training samples of flat roofs and sloping roofs, and classifying the roofs of the area after optimizing the parameters.

[0052] In more detail, the termination filtering method is first used to reduce the noise impact caused by other interferences on the slope layer.

[0053] In this embodiment, if the average slope in the area is greater than 5 degrees, it is set as a pitched roof, and if the average slope is less than 6 degrees, it is set as a flat roof.

[0054] Then, at least 12 known types of roofs are selected as training samples. These samples need to be evenly distributed in the area to ensure the generalization ability of the model. At the same time, the number of samples of flat roofs and sloping roofs should be relatively balanced to avoid the problem of class imbalance. With slope as the classification feature, SVM (Support Vector Machines) is selected to train the classifier, and the training samples and their corresponding roof types are input. After optimizing the parameters, the entire area is classified to complete the classification of roof types.

[0055] Step S133, converting the classification result into a vector file, and extracting the roof data of the flat roof and the pitched roof according to the vector object range.

[0056] In this technical solution, if the average slope in the area is greater than the set value, it is a pitched roof, and if the average slope in the area is less than the set value, it is a flat roof.

[0057] In this technical solution, the building roof data is extracted through the created oblique photography model and digital surface, and the roof types are classified into flat roofs and pitched roofs.

[0058] Step S2, according to the characteristics of the flat roof and the sloping roof in step S1, respectively construct the corresponding flat roof drainage structure and the sloping roof drainage structure, and finally construct a roof drainage model considering the roof type.

[0059] For step S2, refer to Figure 2 and Figure 3 , which mainly includes the following sub-steps.

[0060] Step S21, for flat roofs, due to their small slope, the water flow converges slowly, and gravity is used to achieve water flow convergence. Therefore, the drainage node is set at the geometric center of the flat roof, and the drainage node is used as the starting point of the roof drainage pipe; for sloping roofs, the slope is large, and the water flow converges quickly; unlike flat roofs, sloping roofs usually have downpipes at the edge, and gravity allows water to enter the downpipes, and then drain into the main drainage system. Therefore, the drainage nodes and pipes of sloping roofs are set at the edge of the roof; the specific location distribution can be referred to Figure 2 , and then obtain the flat roof drainage structure and the slope roof drainage structure.

[0061] Step S22, set parameters for the drainage nodes and pipes in the flat roof drainage structure and the slope roof drainage structure. More specifically, set the parameters of the drainage nodes and pipes as needed, and the main setting parameters include: pipe material, pipe diameter, pipe roughness, pipe slope, node width; set the drainage pipe network parameters for the flat roof and slope roof according to the roof type, and the specific pipe parameters are shown in Table 1: Table 1 Pipeline specific parameter settings parameter Flat roof Sloped roof Pipes and pipes Cast iron pipe / plastic pipe Cast iron pipe / plastic pipe Pipe diameter 75 / 100 mm 100 / 150 mm Pipe roughness Cast iron pipe (0.013) / plastic pipe (0.009) Cast iron pipe (0.013) / plastic pipe (0.009) Pipeline slope 0.003 0.005 Node width is an important parameter used in calculating the width of the node overflow. The calculation formula for the node overflow width is as follows: , In the above formula, b is the node overflow width (m); is the maximum overflow water volume (L / s); N is the node overflow width coefficient; g is the gravity acceleration, which is 9.81 m / s 2 ; is the maximum designed water accumulation height on the roof (m); is the distance from the bottom of the node to the roof (m).

[0062] Step S23: construct a roof drainage model taking into account the roof type based on the drainage network structure and parameter setting results.

[0063] In more detail, based on the drainage network structure and the results of the drainage network parameter determination, GIS software is used to input the designed drainage network structure and the determined parameter values, check the topological relationship, and build the roof drainage model. The key to this step is to ensure the accuracy and rationality of all input data so as to obtain reliable simulation results.

[0064] In this technical solution, according to the characteristics of flat roofs and sloping roofs, flat roof drainage structures and sloping roof drainage structures are constructed respectively, and the set parameters are combined to construct a roof drainage model that takes the roof type into consideration.

[0065] Step S3, integrating the rooftop drainage model with the urban community hydrological model taking the roof into consideration, and running the urban community hydrological model to simulate ground water accumulation in the urban community.

[0066] Step S3 mainly includes the following sub-steps.

[0067] Step S31, connect the rooftop drainage nodes with the nodes of the urban drainage pipe network system, input data into the rooftop drainage model, and combine it with the urban community hydrological model to complete the rooftop drainage model integration.

[0068] Prior to this step, the method also includes: dividing the watershed areas of flat roofs and sloping roofs, and marking a roof drainage node for each watershed area according to the geographical location of the drainage node that matches the geographical range of the watershed area.

[0069] For more details, see Figure 3 , due to the small slope of a single flat roof, the entire flat roof is considered as a single catchment area. If a single flat roof has elevation differences or multiple drainage points, the roof is divided into smaller areas based on the elevation and drainage path, and each area corresponds to a major drainage point. For pitched roofs, the catchment area is divided according to the ridge line. With the ridge line as the boundary line, each part forms an independent catchment area, which is defined by the ridge line and the edge of the roof. After the catchment area is divided, GIS software is needed to calculate the parameters related to the catchment area and assign them to the catchment area.

[0070] The proportion of impervious surface is 100%, the slope is the average slope in the catchment area, and the Manning roughness coefficient is 0.012. The width of the catchment area is expressed as: , Where W is the width of the catchment area; K is the runoff coefficient; S is the catchment area (m 2 ).

[0071] Afterwards, in the GIS software, according to the geographical location of the drainage node that matches the geographical scope of the catchment area, each catchment area needs to be matched and marked with a drainage node to complete the labeling work of the catchment area division.

[0072] After that, the roof drainage nodes are connected with the nodes in the urban drainage network system to ensure that the roof drainage data can accurately flow into the urban drainage hydrological model. Then, the runoff data generated by the roof drainage model is used as input and combined with other input data (surface runoff, soil permeability) in the urban community hydrological model. By setting appropriate model parameters (pipe roughness coefficient, node type), the roof drainage model integration is completed. For details, please refer to Figure 3 .

[0073] In this technical solution, after completing the division of the catchment area, a roof drainage node is matched and marked for each catchment area, and then the roof drainage node is connected to the node in the urban drainage network system to ensure that the roof drainage data can accurately flow into the urban drainage hydrological model.

[0074] Step S32, constructing a one-dimensional urban community hydrological model and a two-dimensional urban community hydrological model in sequence.

[0075] More specifically, the marked catchment area and land use data are input into the professional hydrological model, and the various parameters required by the model are set, such as the roughness coefficient of the pipeline and the type of node, to complete the establishment of a one-dimensional urban community hydrological model in the software.

[0076] The one-dimensional urban community hydrological model can simulate the water flow dynamics of the urban drainage system. Its core equations are the Manning equation and the Saint-Venant equation, as follows: , In the above formula, is the water velocity (m / s); n is the roughness coefficient; R is the hydraulic radius (m), which is equal to the cross-sectional area A divided by the wetted perimeter P; S is the slope; Q is the pipe flow rate (m 3 / s); t is the simulation time (s); x is the length along the pipeline (m); A is the water-passing section (m 2 ); g is the acceleration due to gravity, which is 9.81 m / s 2 ; z is the ground elevation (m); The friction slope.

[0077] Through the above formula, we can get v and Q. We need to calculate the overflow water volume of each node. The calculation formula is as follows: , In the formula, is the node overflow water volume (m3 ), is the inflow volume of each node (m 3 ).

[0078] When constructing a two-dimensional urban community hydrological model, first use a high-precision digital elevation model (DEM) and land use data to divide the area into regular or irregular grid cells through GIS software. Define the physical properties of each grid cell in the software, such as surface roughness and slope, and set initial and boundary conditions. Set the runoff coefficient and infiltration rate of each grid cell according to the surface cover type and soil properties. After completing the above settings in the GIS software, input the grid cells and the output of the one-dimensional urban hydrological model into the two-dimensional urban community hydrological model. The physical properties of each grid cell, surface roughness and slope, need to be defined in the model. In addition, the runoff system and infiltration rate of each grid cell need to be set according to the surface cover type and soil properties. The core equation of the two-dimensional model is the shallow water equation, which can describe the movement of water in the horizontal direction. The equation is as follows: , In the above formula, h is the surface water depth (m); t is the simulation time (s); x and y are the distances along the pipeline and perpendicular to the pipeline on the horizontal plane (m); u and v are the speeds of the water flow in the x and y directions (m / s); g is the gravitational acceleration, which is 9.81m / s here. 2 ; is the friction slope in the x and y directions; is the grid unit area (m 2 ).

[0079] The node overflow water volume data output by the one-dimensional urban hydrological model As the input of the two-dimensional urban hydrological model, the water accumulation height h of the grid cell is calculated. Set an appropriate simulation time step and simulation time t, to complete the construction of the urban community hydrological model taking into account the building roofs.

[0080] In this technical solution, the construction of an urban community hydrological model taking into account building roofs aims to more accurately assess the waterlogging risk and drainage capacity of urban communities. The model comprehensively considers the drainage characteristics of different types of roofs, including the water storage and drainage capacity of flat roofs and sloping roofs, and combines multiple factors such as meteorology, topography, and land use to establish a multi-factor coupled hydrological model. By using high-resolution remote sensing data and terrain data, the spatial resolution and accuracy of the model are improved. In addition, the model realizes real-time simulation and prediction of urban hydrological processes through real-time monitoring and dynamic updating.

[0081] Step S33, simulating ground waterlogging in urban communities and generating simulation results, which are raster layers based on waterlogging depth.

[0082] In more detail, through the integration of the above-mentioned roof drainage model and the construction of an urban community hydrological model that takes into account the roofs of buildings, running the urban community hydrological model can realize the simulation of ground water in urban communities, and the simulation result is a raster layer based on the depth of water accumulation.

[0083] In this technical solution, the corresponding roof data is first extracted through oblique photography model data and digital surface data, and the corresponding roof drainage structure is constructed according to the different roof types to establish its roof drainage model; the roof drainage model is integrated with the urban community hydrological model that takes the roof into consideration, and finally the simulation process of urban community area water is realized, realizing the real-time simulation and prediction of urban hydrological processes.

[0084] Example 2 On the basis of Example 1, this example further proposes an urban community ground water surface simulation system taking into account the roof structure, which mainly includes a data extraction module, a model construction module and a simulation module.

[0085] Among them, the data extraction module is connected with the model construction module, and the model construction module is connected with the simulation module.

[0086] The data extraction module mainly performs the functions of extracting roof data and classifying roof types. Specifically, the roof data is extracted according to the oblique photography model and the digital surface model, and the roofs are classified into flat roofs and pitched roofs. For more details, please refer to step S1 in Example 1.

[0087] The main functions of the model building module are to construct the drainage structure and the roof drainage model. Specifically, the flat roof drainage structure and the slope roof drainage structure are first constructed, and then the drainage network parameters are combined to construct a roof drainage model that takes into account the roof type. For more details, please refer to step S2 in Example 1.

[0088] The simulation module mainly performs the function of integrating the urban community hydrological model and the roof drainage model to simulate ground water accumulation in the urban community. For more details, please refer to step S3 in Example 1.

[0089] The system of this technical solution mainly includes a data extraction module, a model building module and a simulation module. The three modules perform the above functions in sequence to complete the simulation of ground surface water and realize real-time simulation and prediction of urban hydrological processes.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A method for simulating ground water in urban communities considering roof structures, characterized in that: The following steps are involved: S1, collect multi-angle photo data to build an oblique photography model and a digital surface model, extract roof data from the digital surface model, and classify roof types into flat roofs and pitched roofs; S2, according to the characteristics of flat roofs and sloping roofs, construct flat roof drainage structures and sloping roof drainage structures respectively, and then construct a roof drainage model considering the roof type; S3, integrate the rooftop drainage model with the urban community hydrological model that takes rooftops into account, and run the urban community hydrological model to simulate ground water accumulation in urban communities.

2. A method for simulating ground water in urban communities considering roof structures according to claim 1, characterized in that: The step S1 comprises: S11, stitching the multi-angle photos to generate an oblique photography model, and reconstructing a digital surface model through the oblique photography model; S12, separating the ground data of non-building ground data from the digital surface model, extracting the initial roof data, eliminating irrelevant ground objects, and generating roof elevation raster data; S13, the roof types are divided into flat roofs and pitched roofs according to the roof slope to generate classification results.

3. A method for simulating ground water in urban communities taking into account roof structures according to claim 1 or 2, characterized in that: The step S2 comprises: S21, set the drainage node of the flat roof at its geometric center, and use the drainage node as the starting point of the roof drainage pipe; the drainage node and downpipe of the pitched roof are both set at the edge of the roof; S22, setting parameters of drainage nodes and pipes in the flat roof drainage structure and the slope roof drainage structure; S23, based on the results of drainage network structure and parameter setting, a roof drainage model considering the roof type is constructed.

4. The method for simulating ground water in urban communities considering roof structures according to claim 3 is characterized in that: The step S3 comprises: S31, connect the roof drainage nodes with the nodes of the urban drainage network system, input data into the roof drainage model, and combine it with the urban community hydrological model to complete the roof drainage model integration; S32, sequentially constructing a one-dimensional urban community hydrological model and a two-dimensional urban community hydrological model; S33 simulates ground waterlogging in urban communities and generates simulation results, which are raster layers based on waterlogging depth.

5. The method for simulating ground water in urban communities considering roof structures according to claim 2 is characterized in that: The step S12 comprises: The PMF method is used to extract ground data, and then the ground data of the digital surface model is separated; the initial roof data is extracted according to the characteristics of the ground objects and combined with visual recognition technology, and the initial roof data is output as roof range mask data. According to the roof range mask data, irrelevant ground objects are eliminated to generate roof elevation raster data.

6. The method for simulating ground water in urban communities considering roof structures according to claim 5 is characterized in that: The step S13 comprises: S131, traverse the roof elevation grid data pixels, calculate the slope of the roof, and save the calculated slope grid layer; S132, taking slope as a classification feature, selecting SVM training classifier, training samples of flat roofs and sloping roofs, and classifying the roofs of the area after optimizing parameters; S133, converting the classification result into a vector file, and extracting the roof data of the flat roof and the pitched roof according to the vector object range.

7. The method for simulating ground water in urban communities considering roof structures according to claim 3 is characterized in that: The S23 is specifically: According to the results of drainage network structure and parameter setting, the designed drainage network structure and determined parameter values ​​are input into GIS software, the topological relationship is checked, and the roof drainage model is constructed.

8. The method for simulating ground water in urban communities considering roof structures according to claim 4 is characterized in that: The core equations of the one-dimensional urban community hydrological model are the Manning equation and the Saint-Venant equation, and the core equation of the two-dimensional urban community hydrological model is the shallow water equation.

9. A method for simulating ground water in urban communities taking into account roof structures according to claim 4 or 8, characterized in that: Before step S31, the following steps are also included: Flat roofs and pitched roofs are divided into watershed areas, and a roof drainage node is marked for each watershed match according to the geographical location of the drainage node that matches the geographical range of the watershed area.

10. A system for simulating ground water in urban communities taking into account roof structures, applicable to a method for simulating ground water in urban communities taking into account roof structures as claimed in any one of claims 1 to 9, characterized in that: include: Data extraction module, which extracts roof data through oblique photography model and digital surface model, and classifies roof types into flat roof and pitched roof Model building module, constructs flat roof drainage structure and slope roof drainage structure, and combines drainage network parameters to build a roof drainage model that takes into account roof types; The simulation module integrates the urban community hydrological model and the roof drainage model to simulate ground water accumulation in urban communities.

Images