Method for determining coverage area of fire rescue station based on block as unit

Abstract

The invention is suitable for the technical field of fire safety, and relates to a method for determining the coverage area of a fire rescue station based on a block as a unit, which is simple in process and high in accuracy, systematically divides the fire rescue accessibility of an urban area by adopting a block division standard more conforming to practical application, and determines the coverage area of the fire rescue station by combining real-time traffic data. The fire rescue accessibility of each block is accurately evaluated, grade division is carried out, and the responsibility jurisdiction of each fire station is reasonably divided. According to the method, the fire rescue response capability of different areas of a city under actual traffic conditions can be reflected more truly, and a fire department can be helped to reasonably divide responsibility jurisdictions of all fire stations, so that a scientific basis is provided for optimization of fire station layout and scheduling of fire rescue resources; the evaluation precision and scientificity of urban fire safety management are improved, and the effectiveness of fire prevention and control is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of fire safety, and in particular relates to a method for determining the coverage area of ​​a fire rescue station based on blocks as units. Background Art

[0002] In recent years, with the acceleration of urbanization, building density and population concentration have increased year by year, and the risk of fire has increased significantly. This trend is particularly evident in old urban areas, commercial areas and areas with dense high-rise buildings. When responding to fires, it is crucial for fire rescue forces to arrive at the fire site in a timely manner. Reasonable division of fire responsibility areas and dispatch of fire rescue resources are fundamental to ensuring the effectiveness of fire safety management.

[0003] At present, when fire departments allocate and dispatch rescue resources, they often divide the fire rescue responsibility area by block. The academic community mainly guides the division of responsibility areas based on the coverage of fire rescue. The research on the coverage of fire rescue mainly relies on traditional methods such as isochronal circles and boundary search. These methods often fail to fully consider the actual conditions such as road network morphology and terrain, and cannot directly and effectively support the fire department to carry out reasonable division of responsibility areas and dispatch fire rescue resources, resulting in unreasonable and unscientific problems in the division of fire rescue responsibility areas and the dispatch of fire rescue resources. The patent application with the announcement number CN113848881B discloses a fire truck path planning method, system, terminal and storage medium, the method includes obtaining an environmental model; based on the environmental model, obtaining search boundary information and obstacle information, and using target trend rapid expansion tree search to obtain a global path; based on the global path, sending a control signal to the fire truck so that the fire truck moves from the fire station to the target point along the global path; receiving fixed obstacle information fed back during the walking process of the fire truck, and correcting the current posture of the fire truck based on the received fixed obstacle posture; receiving dynamic obstacle information fed back during the walking process of the fire truck, predicting obstacle motion collision based on the received dynamic obstacles, and determining whether to perform local path planning based on the prediction results, and using local path planning to update the global path. This patent also uses a boundary search method to achieve the management of fire resource distribution and fire resource allocation, and has the same disadvantages as the prior art.

[0004] Therefore, how to provide a method for determining the coverage area of ​​fire rescue stations based on blocks, so as to scientifically divide the fire rescue responsibility areas, rationally allocate rescue resources, and improve the utilization rate of fire resources is an urgent problem to be solved by personnel in this technical field. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for determining the coverage area of ​​a fire rescue station based on blocks, so as to solve the unreasonable and unscientific problems in the prior art of the division of fire rescue responsibility areas and the scheduling of fire rescue resources.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for determining the coverage range of a fire rescue station based on a block as a unit, comprising the following steps:

[0008] S10, determine the calculation area and fire station, obtain the area boundary and fire station location, obtain the area base map, binarize the area map, and pick up the outlines of each enclosed area except the road; S20, establish a coordinate system for the binarized image, create a base point, calculate the boundary range of the block divided by the road according to the image outline, divide the block unit, calculate and record the expression of the boundary of each block unit; S30, determine the number and location of the fire rescue demand points in the selected area, and pre-process the collected data; S40, convert the fire stations and demand points in the selected area into the Mercator coordinate system, and convert the latitude and longitude coordinates into pixels The coordinates are mapped to the drawing area of ​​the block boundary obtained by image recognition to determine the block where the demand point is located; S50, calculate the time it takes for the fire truck to reach the demand point from each fire station, and determine the weighted accessibility time from each fire station to each demand point while considering the travel time reduction factor; S60, calculate the average accessibility time of the entire block, divide the responsibility area of ​​each block unit, calculate the area of ​​the responsibility area of ​​each fire station, and generate a map for visual display; S70, calculate the average accessibility time of the entire block, divide the block units into accessibility levels, calculate the area and coverage of each accessibility level, and generate a map for visual display.

[0009] Furthermore, in step S10, the target area to be calculated is clarified, the area boundary is obtained, the administrative boundary of the area is extracted through the online map API or the boundary coordinates of a specific area are manually selected, and it is assumed that there are z blocks within the selected range, and the numbers and geographic coordinate positions of the fire stations to be calculated in the area are recorded;

[0010] After determining the calculation area, a custom map is made for this area, and the image is binarized, with all roads assigned white and other areas assigned black. After the custom map is enlarged to a size that can display the shape of the road network, the area to be calculated is intercepted.

[0011] Furthermore, in step S20, the lower left vertex of the pixel at the lower left corner of the region range image is taken as (0,0), and the side length of 1 pixel is taken as a unit of 1. When traversing the turning points of the region boundary, the point with the smallest longitude and latitude coordinates is selected as the base point, and the longitude and latitude of the region boundary are traversed to find the point with the smallest longitude coordinate among all the turning points of the boundary. lon , whose longitude is lon min ; Traverse the point O with the smallest latitude coordinate among the turning points of the boundary of the region lat , whose latitude is lat min , create the base point O(lon min ,lat min );

[0012] Starting from the position (0,0), scan the image line by line within the image range to find the boundary of black pixels, track the boundary, and check the four neighboring pixels around the starting point. If there are four neighboring pixels with different colors, it is defined as the internal area boundary point P. i , after finding a black pixel, trace the contour along its boundary. After finding a path, continue to scan the image line by line, and repeat the above operation until all black pixel boundaries are found;

[0013] Select the jump point as the starting point of the closed path, traverse all points on the contour, find the point pair with the largest distance, and use the last point in the point pair as the jump point;

[0014] The closed path is simplified recursively to reduce redundant points in the path. According to each path after path simplification, the key points of all paths are output and recorded.

[0015] Furthermore, in step S30, it is assumed that an area to be calculated has been determined, and there are m fire rescue demand points in the area, and the fire rescue demand points include buildings, schools, and hospitals. The locations of the fire rescue demand points are obtained through on-site surveys, online maps, social media, government public data, and historical fire records. Fire rescue demand points are added to grid vertices within a certain number of meters of the natural geographical area in the area. At the same time, the collected data is preprocessed to remove duplicate points and correct erroneous data.

[0016] Furthermore, in step S40, each selected area boundary point, fire rescue demand point, and fire station is mapped in the drawing area using Mercator coordinate system transformation, and the formula is as follows:

[0017]

[0018] Among them, X and Y represent the horizontal and vertical coordinates of the drawing area after mapping, respectively. width and G heightRespectively represent the width and height of the drawing area.

[0019] Furthermore, in step S50, the driving time of an ordinary car from a certain starting point to a destination is obtained by calling online maps and GIS services to obtain real-time traffic data. According to the Road Traffic Safety Law and the Fire Protection Law, when performing emergency tasks, other vehicles must give way to fire trucks. The driving time of fire trucks from fire stations to fire rescue demand points must be less than the driving time of normal cars. The reduction coefficient is set to β t , β t The value is generally less than or equal to 1. The travel time between the fire truck and the rth demand point is T' r , T pre is the time when the fire truck is ready to depart, then the actual driving time Tr of the fire truck from the corresponding fire station to the fire rescue demand point is as follows:

[0020] Tr=β t ·T' r +T pre , 0<β t ≤1.

[0021] Furthermore, in step S60, for each fire station b, the driving time from b to all demand points in block α is calculated, where there are v fire rescue demand points in block α, and the weighted accessibility time from fire station b to all demand points in block α is averaged to obtain the overall average accessibility time of fire station b to block α. The formula is as follows:

[0022]

[0023] After obtaining the average overall accessibility time of all fire stations to block α, compare the average rescue time of all fire stations, select the fire station with the shortest average accessibility time as the main responsible fire station for block α, and then deduced the average overall accessibility time of other fire stations to block α. Take the fire station with the shortest average overall accessibility time of all fire stations to block α, and divide the range of block α into the responsibility area of ​​fire station b.

[0024] Furthermore, the area of ​​each unit is calculated using the Gaussian formula. For each fire station, the areas of all the blocks it is responsible for are added up, and then the responsibility areas of each fire station are divided according to the scope of their jurisdiction. Different textures are given to distinguish the responsibility areas of each fire station, and they are visualized to intuitively show the scope of each fire station after calculation.

[0025] Furthermore, in step S70, the rescue accessibility of each block in the area is divided according to the calculated average accessibility time of all demand points in the block, and the expression is as follows:

[0026]

[0027] Assign each type of accessible block is the accessible block category, if If i is the i-type neighborhood, where i∈[1,n], ω i is the average accessibility time of a flat block.

[0028] Furthermore, the areas of each type of block are summed up, and the coverage rate of each type is calculated based on the proportion of the area of ​​each type of block to the total area. For each fire station, the areas of all the blocks it is responsible for are added up, and the various types of blocks are divided into accessibility levels. Each type of block is then visualized to intuitively show the range of accessibility levels after calculation.

[0029] Compared with the prior art, the method for determining the coverage range of fire rescue stations based on blocks as units provided by the present invention has at least the following beneficial effects:

[0030] Existing fire departments often fail to fully consider the actual conditions such as road network morphology and terrain when allocating and dispatching rescue resources, and cannot directly and effectively support the fire departments to carry out reasonable division of responsibility jurisdictions and dispatch of fire rescue resources, resulting in unreasonable and unscientific problems in the division of fire rescue responsibility jurisdictions and the dispatch of fire rescue resources. The process of the present invention is simple and accurate. It adopts a block division standard that is more in line with practical applications to systematically divide the fire rescue accessibility of urban areas. By combining real-time traffic data, it accurately evaluates the fire rescue accessibility of each block, and performs grade division and reasonable division of the responsibility jurisdiction of each fire station. The present invention can not only more truly reflect the fire rescue response capabilities of different areas of the city under actual traffic conditions, but also help the fire department to reasonably divide the responsibility jurisdiction of each fire station, provide a scientific basis for the optimization of fire station layout and the dispatch of fire rescue resources, and help improve the assessment accuracy and scientificity of urban fire safety management, and enhance the effectiveness of fire prevention and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the scheme of the present invention, a brief introduction is given below to the figures required for use in the description of the embodiments. Obviously, the figures described below are some embodiments of the present invention. For ordinary technicians in this field, other figures can be obtained based on these figures without paying any creative work.

[0032] Figure 1 A flowchart of a method for determining the coverage area of ​​a fire rescue station based on blocks as units provided by an embodiment of the present invention;

[0033] Figure 2 A regional range map determined and calculated in a method for determining a fire rescue station coverage range based on blocks as units provided in an embodiment of the present invention;

[0034] Figure 3 In a method for determining the coverage range of a fire rescue station based on a block as a unit provided in an embodiment of the present invention, the regional range is determined. Figure 2 The valued graph;

[0035] Figure 4 An internal area boundary map in a method for determining the coverage range of a fire rescue station based on a block as a unit provided in an embodiment of the present invention;

[0036] Figure 5 A diagram after scanning the internal area boundary in a method for determining the coverage range of a fire rescue station based on blocks as units provided by an embodiment of the present invention;

[0037] Figure 6 A visualization diagram of the scope of responsibility areas of each fire station in a region in a method for determining the coverage area of ​​a fire rescue station based on a block as a unit provided in an embodiment of the present invention;

[0038] Figure 7 A visualization diagram of the area and coverage rate of each accessibility level in a region in a method for determining the coverage range of a fire rescue station based on blocks as units provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0041] The embodiment of the present invention provides a method for determining the coverage range of a fire rescue station based on a block as a unit, which is applied to the research and application process of the coverage range of a fire rescue station. The method for determining the coverage range of a fire rescue station based on a block as a unit includes the following steps:

[0042] S10, determine the calculation area and fire station, obtain the area boundary and the location of the fire station, obtain the area base map, binarize the area map, and pick up the outlines of each enclosed area except the road; S20, establish a coordinate system for the binarized image, create a base point, calculate the boundary range of the block divided by the road according to the image outline, divide the block unit, calculate and record the expression of the boundary of each block unit; S30, determine the number and location of the fire rescue demand points in the selected area, and pre-process the collected data;

[0043] S40. Perform Mercator coordinate system conversion on the fire stations and demand points in the selected area, convert the longitude and latitude coordinates into pixel coordinates and map them to the drawing area of ​​the block boundary obtained by image recognition to determine the block where the demand point is located; S50. Calculate the time it takes for the fire truck to get from each fire station to the demand point, and determine the weighted accessibility time from each fire station to each demand point while considering the travel time reduction factor; S60. Calculate the average accessibility time of the block as a whole, divide the responsibility area of ​​each block unit, calculate the area of ​​the responsibility area of ​​each fire station, and generate a map for visual display; S70. Calculate the average accessibility time of the block as a whole, divide the block units into accessibility levels, calculate the area and coverage of each accessibility level, and generate a map for visual display.

[0044] The process of the present invention is simple and accurate. It adopts a block division standard that is more in line with practical applications, systematically divides the fire rescue accessibility of urban areas, and accurately evaluates the fire rescue accessibility of each block by combining real-time traffic data, and performs grade division and reasonable division of the responsibility area of ​​each fire station. The present invention can not only more truly reflect the fire rescue response capabilities of different areas of the city under actual traffic conditions, but also help the fire department to reasonably divide the responsibility area of ​​each fire station, provide a scientific basis for the optimization of the layout of fire stations and the dispatch of fire rescue resources, and help improve the assessment accuracy and scientificity of urban fire safety management, and enhance the effectiveness of fire prevention and control.

[0045] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0046] The present invention provides a method for determining the coverage range of fire rescue stations based on blocks, which is applied to the research and application of the coverage range of fire rescue stations. Figures 1 to 7 In this embodiment, the method for determining the coverage range of the fire rescue station based on the block as a unit includes the following steps:

[0047] S10, determine the calculation area and the fire station, obtain the area boundary and the fire station location, obtain the area base map, perform binarization processing on the area map, and pick up the outlines of each enclosed area except the road.

[0048] Specifically, it is necessary to clearly define the target area for calculation, which can be a pre-set urban area or a custom arbitrary range. Secondly, the regional boundaries must be obtained. Boundary acquisition can be achieved by extracting regional administrative boundaries through the online map API, or manually selecting boundary coordinates of a specific area according to actual needs. Assuming that there are z blocks within the selected range, when obtaining regional boundaries, areas with lower latitudes can usually provide more accurate calculation results. Due to the curvature of the earth, the error of coordinate system conversion will increase at higher latitudes, thereby affecting the accuracy of the calculation. At the same time, the numbers of the fire stations that need to be calculated in the area and their geographic coordinate positions are recorded.

[0049] In this embodiment, a region to be calculated in a city is selected, and the region range is as follows: Figure 2 As shown, there are four fire stations that need to be calculated at the same time: Fire Station 1 has coordinates (113.873361, 22.783574), Fire Station 2 has coordinates (113.875334, 22.773865), Fire Station 3 has coordinates (113.876401, 22.789415), and Fire Station 4 has coordinates (113.871003, 22.780899).

[0050] Furthermore, in this embodiment, after the calculation area is determined, a customized map is made for the area to perform binarization processing on the image, all roads are assigned white color, and other areas are assigned black color. After the customized base map is enlarged to a size that can display the shape of the road network, the area to be calculated can be captured with the help of a high-definition display. If the selected range is too large, you can also choose to download related tile maps and merge them.

[0051] In this embodiment, the map within the area is binarized, and the pictures of the area involved are extracted. Figure 3 shown.

[0052] S20, establishing a coordinate system for the binarized image, creating base points, calculating the boundary range of the block divided by roads according to the image contour, dividing the block units, and calculating and recording the expression of the boundary of each block unit.

[0053] Specifically, the lower left vertex of the pixel at the lower left corner of the area range image is taken as (0,0), and the side length of 1 pixel is taken as unit 1.

[0054] In this embodiment, Figure 3 Set the coordinate system and unit, take the coordinate of the lower left corner as (0,0), and the side length of a pixel as 1.

[0055] Furthermore, in this embodiment, the base point is created to determine a reference point in the map area, which is convenient for subsequent coordinate mapping. When traversing the turning points of the area boundary, the point with the smallest longitude and latitude coordinates is selected as the base point. The reason for selecting the smallest longitude and latitude is to ensure that the base point is at the lower left of the map, which can be consistent with a common coordinate system (such as a Cartesian coordinate system), thereby simplifying subsequent calculations and mapping operations. The longitude and latitude of the area boundary are traversed to find the point with the smallest longitude coordinate among all the boundary turning points. lon , whose longitude is lon min Similarly, traverse the point O with the smallest latitude coordinate among the turning points of the boundary of the region lat , whose latitude is lat min , based on this, create the base point O(lon min ,lat min ).

[0056] In this embodiment, the minimum longitude value in the area is 113.832545, the maximum longitude value is 113.901947, the minimum latitude value is 22.722021, and the maximum latitude value is 22.831542, that is, Figure 3 The latitude and longitude coordinates of the lower left corner are (113.832545, 22.722021), and the coordinates of the upper right corner are (113.901947, 22.831542).

[0057] Furthermore, in this embodiment, starting from the position (0, 0), the image is scanned line by line within the image range to find the boundary of the black pixel and track the boundary. The four neighboring pixels around the starting point are checked. If there are four neighboring pixels with different colors, they are defined as the internal area boundary point P. i ,like Figure 4 shown.

[0058] After finding a black pixel, trace the contour along its boundary. During the trace, each step is called a "unit step", which means moving from the current pixel to the next turning point, following the rule of "white pixels on the left and black pixels on the right". Unit steps can only move in four basic directions: up, down, left, and right (such as Figure 4 As shown in the figure, a unit step path is defined as the shortest path from a pixel point to an adjacent pixel point along these four directions. The outline of each black area is composed of a series of unit steps, forming a complete "unit step path". If there are k complete "unit step paths" in the area, the sum of these paths constitutes the outline of the entire image. After finding a path, continue to scan the image line by line, and repeat the above operation until all black pixel boundaries are found.

[0059] Furthermore, in this embodiment, a jump point is selected as the starting point of the closed path. The jump point refers to the point where the distance between two adjacent contour points on the path suddenly increases. This point generally corresponds to the part of the image contour where the shape changes suddenly, such as the point where the edge of the contour changes sharply. All points on the contour are traversed: the Euclidean distance between each point and its previous point is calculated, and then the distances of the points on the same "unit step path" are compared: the point pair with the largest distance is found, and the second point in the point pair is used as the jump point.

[0060] For the α path (P 0 →P 1 →P 2 →P 3 →...→P n-1 →P 0 ), where each point P i =(x i ,y i ), calculate all two adjacent points P i and P i-1 The Euclidean distance d between i :

[0061]

[0062] Find the maximum distance and its index:

[0063] d max =max(d 1 ,d 2 ,...,d n-1 )

[0064] j = argmax(d 1 ,d 2 ,...,d n-1 )(find the index of maximum distance).

[0065] Then for the α path (P 0 →P 1 →P 2 →P 3 →...→P n-1 →P 0 )’s jumping point is: J = P j The determined jump point J is used as the starting point of the closed path. Next, an end point T needs to be determined. The point T farthest from the jump point J can be selected by calculating the Euclidean distance between each contour point and the jump point.

[0066] For every point P in the closed path i , calculate its distance to the jump point J:

[0067]

[0068] Find the maximum distance d max And its corresponding point T:

[0069] d max =max(d 1 ,d 2 ,...,d n )

[0070] T=P k (where d k =d max ).

[0071] Furthermore, in this embodiment, the closed path is simplified, and redundant points in the path are reduced in a recursive manner, while ensuring that the shape of the path does not change significantly.

[0072] Processing closed paths, defining α paths (P 0 →P 1 →P 2 →P 3 →...→P n-1 →P 0 ) is the jumping point (x j ,y j ), T(x k ,y k ) is the point farthest from point J in a straight line, decomposing the closed path α into and

[0073] According to the starting point P j With the end point P k Find the path of the coordinates The straight line expression is:

[0074] Ax+By+C=0.

[0075] Where A = y j -y k , B=x k -x j , C = x j y j -x k y j +y k -y j , traverse the path All the points in the middle, calculate the point P on the path in turn i The distance d i :

[0076]

[0077] Find the path The point P with the largest distance m , if P m If the distance is greater than the set threshold ξ, then P m Is the path The important key points on the path need to be retained. become and

[0078] Now we need to get the path and The straight line expression of the path Traverse all points in the middle of the path to the path distance to the path The point with the largest distance is further judged by the threshold ξ. If the point with the largest distance is still an important key point, it will continue to be retained and the path will continue to be decomposed until all the middle points of the path are less than the set threshold ξ. and path Perform the same operation.

[0079] Furthermore, in this embodiment, based on each path after path simplification processing, the key points of these paths (including the starting point, the end point and the key nodes in the middle) are output and recorded. Each path corresponds to a set of line segments, and these line segments can be represented by mathematical expressions. In this step, all generated paths are numbered and their specific geometric information is recorded, such as the starting point and end point coordinates of the line segment and the expression.

[0080] S30: Determine the number and location of fire rescue demand points in the selected area, and pre-process the collected data.

[0081] Specifically, it is assumed that the area to be calculated has been determined. There are m fire rescue demand points in the area, where fire rescue demand points refer to potential fire risk points such as buildings, schools, and hospitals. The locations of fire rescue demand points are obtained through on-site surveys, online maps, social media, government public data, historical fire records, etc. At the same time, in order to ensure full coverage of the area, d fire rescue demand points are calculated in the area except for natural geographical areas such as foothills and rivers. x ×d y Fire rescue demand points are added at the grid vertices of meters, and the collected data are preprocessed to remove duplicate points and correct erroneous data.

[0082] In this embodiment, since the number and location of fire stations have a direct impact on the fire rescue level of an area, the location and number of fire stations in the area are determined through on-site investigations to ensure the accuracy of the fire stations. At the same time, the location information of the demand points is collected through on-site investigations, checking online maps such as Amap, government public data, historical fire records, etc. The collected demand point data is pre-processed to remove duplicate points, correct erroneous longitude and latitude information, etc. to ensure the accuracy and validity of the data. Finally, it is found that there are 12,282 fire rescue demand points in the area.

[0083] S40, performing Mercator coordinate system conversion on the fire stations and demand points in the selected area, converting the longitude and latitude coordinates into pixel coordinates and mapping them to the drawing area of ​​the block boundary obtained by image recognition, and determining the block where the demand point is located.

[0084] Specifically, each geographic object (selection area boundary point, fire rescue demand point, fire station) is mapped in the drawing area using the Mercator coordinate system transformation. In the formula, X and Y respectively represent the horizontal and vertical coordinates of the drawing area after mapping.

[0085]

[0086] Among them G width and G height Respectively represent the width and height of the drawing area.

[0087] In this embodiment, Figure 2 The latitude and longitude coordinates of the lower left corner are (113.832545, 22.722021) and the upper right corner are (113.901947, 22.831542). The width of the experimental area is 12914 pixels and the height is 22097 pixels. It is known that there are four fire stations nearby: Fire Station 1 has a coordinate of (113.873361, 22.783574) and Fire Station 2 has a coordinate of (113.8764 01,22.789415), the coordinates of fire station 3 are (113.875334,22.773865), and the coordinates of fire station 4 are (113.871003,22.780899). Then the coordinates of fire stations 1, 2, 3, and 4 in the figure are: (7485,12347), (7698,13446), (7631,10885), and (7250,12070).

[0088] Furthermore, in this embodiment, a set P is defined as follows: 1 ,P 2 ,...,P z}, where each element represents a block polygon, containing the coordinates of all its vertices, and the polygon enclosed by block α is P α ={(xα1 ,y α1 ),(x α2 ,y α2 ),...,(x α z,y α z)}, all demand points only need to determine whether the point is located in the first intersecting polygon.

[0089] Let the pixel coordinates of point P be (x p ,y p ), choose to emit a horizontal ray to the right, that is, from point P to (+∞,y p ). Assume that block α is the polygon that P intersects first. For each edge of block α, determine whether the ray intersects according to the following conditions:

[0090] Assume that the coordinates of the two endpoints of the i-th side of α are (x αi ,y αi ),(x αi+1 ,y αi+1 ), the condition for the ray to intersect the edge is expressed as:

[0091] The edge is within the y range of the ray:

[0092] (y αi >y αp )≠(y αi+1 >y αp ).

[0093] If the above is true, then calculate the intersection point (x intersect ,y intersect )'s x coordinate xintersect:

[0094] Then exclude interference from special circumstances:

[0095]

[0096] 1. Vertex checking, i.e. the intersection of a ray and a polygon vertex should not be calculated if:

[0097]

[0098] You need to skip this point.

[0099] 2. Check for overlapping edges, i.e. if the ray coincides with an edge of the polygon, this edge should be ignored.

[0100]

[0101] You need to skip this point.

[0102] For each edge, perform the above intersection condition check and check the number of intersections. If the number of intersections is an odd number, the point is inside the polygon; if it is an even number, the point is outside the polygon, that is, let count be the number of intersections between the ray and the polygon edge, which can be expressed as:

[0103]

[0104] Among them I i is the indicator function, defined as follows:

[0105]

[0106] The final judgment is: if the number of intersection points is odd, the point is inside the first intersecting polygon; if the number of intersection points is even, the point is outside the polygon.

[0107] S50, calculating the time it takes for a fire truck to travel from each fire station to the demand point, and determining the weighted accessibility time from each fire station to each demand point in consideration of the travel time reduction coefficient.

[0108] Specifically, the travel time T′ of an ordinary car from a certain starting point to a destination can be obtained by calling online maps, GIS and other services to obtain real-time traffic data. bc (Driving time from fire station b to demand point c), according to the Road Traffic Safety Law and Fire Protection Law, when performing emergency tasks, other vehicles must give way to fire trucks, so the driving time of the fire truck from the fire station to the fire rescue demand point is T′ bc To be shorter than the normal driving time of a car, set a reduction factor β t , reduction factor β t The value is usually less than or equal to 1.

[0109] The travel time T' of a fire truck from a fire station to the rth demand point r It can be calculated by the formula, T pre is the time (in seconds) that the fire truck is ready to depart, and the actual driving time Tr of the fire truck from the corresponding fire station to the fire rescue demand point.

[0110] Tr=β t ·T' r +T pre , 0<β t ≤1.

[0111] In this embodiment, the reduction coefficient β t is 0.9, preparation time T pre is 60 seconds.

[0112] Furthermore, in this embodiment, a period of time is selected as a calculation cycle, u scenarios are set within the cycle, and the time point corresponding to the i-th estimation scenario is ti , the travel time from fire station b to fire demand point c is Tr i,bc , the weighted travel time T from fire station b to demand point c can be obtained by using a similar idea to solve the definite integral bc .

[0113]

[0114] S60. Calculate the average accessibility time of the entire block, divide the responsibility area of ​​each block unit, calculate the responsibility area of ​​each fire station, and generate a map for visual display.

[0115] Specifically, for each fire station b, calculate its driving time to all demand points in block α, where there are v fire rescue demand points in block α. Take the average of the weighted accessibility time of the fire station to all demand points in the block to obtain the overall average accessibility time of the fire station b to the block α.

[0116]

[0117] After obtaining the average overall accessibility time of all fire stations to the block, compare the average rescue time of all fire stations, and select the fire station with the shortest average accessibility time as the main responsible fire station for the block. Similarly, the overall average accessibility time of other fire stations to the block can also be obtained. Take the fire station with the shortest overall average accessibility time of all fire stations to the block, and divide the block into the responsibility area of ​​​​the fire station.

[0118] In this embodiment, since the number and location of fire stations have a direct impact on the fire rescue level of an area, the location and number of fire stations in the area are determined through on-site field surveys to ensure the accuracy of the fire stations. At the same time, the location information of the demand points is collected through on-site surveys, online maps such as Amap, government public data, historical fire records, etc. The collected demand point data is preprocessed to remove duplicate points, correct erroneous longitude and latitude information, etc. to ensure the accuracy and effectiveness of the data. Finally, it is obtained that there are 12218 fire rescue demand points in the area. Assuming that there are 10 fire rescue demand points in the block α, the existing corresponding demand points and their corresponding driving time (unit: second) to the three fire stations A, B, C, and D with the closest straight-line distance are shown in Table 1:

[0119] Table 1

[0120]

[0121] According to the rules: T Aα <T Bα <T Cα <TDα , then block α is considered to be the responsibility area of ​​fire station A.

[0122] Furthermore, in this embodiment, the Gaussian formula is used to calculate the area of ​​each unit. If the existing path (P 0 →P 1 →P 2 →P 3 →...→P n-1 →P 0 ) corresponds to the block α, then the block area S α for

[0123]

[0124] Furthermore, in this embodiment, for each fire station, the areas of all the blocks it is responsible for are accumulated. Let the set of blocks that a fire station is responsible for be {S e1 , S e2 ,...,S en}, then the area of ​​the fire station's jurisdiction is the sum of the areas of these blocks:

[0125]

[0126] Among them, S e总 is the area of ​​the fire station’s jurisdiction, S ei is the area of ​​each block.

[0127] Then, according to the scope of the responsibility area enclosed by each fire station, the responsibility area of ​​each fire station is divided, and different textures are given to distinguish the responsibility area of ​​each fire station. They are visualized to intuitively show the calculated scope of each fire station.

[0128] In this embodiment, Figure 2 The total area of ​​the block in the embodiment is 36203715.45, of which the area under the jurisdiction of Fire Station 1 is 16695605.73, the area under the jurisdiction of Fire Station 2 is 8881513.903, the area under the jurisdiction of Fire Station 3 is 5603574.144, and the area under the jurisdiction of Fire Station 4 is 5023021.674. The visualization results are as follows: Figure 6 shown.

[0129] S70, calculating the average accessibility time of the entire block, dividing the block units into accessibility levels, calculating the area and coverage of each accessibility level, and generating a map for visual display.

[0130] Specifically, according to the calculated average accessibility time of all demand points in the block To divide the rescue accessibility of each block in the area.

[0131]

[0132] Assign each type of accessible block is the accessible block category, if If i is i, it is a type i neighborhood, where i∈[1,n], ω i is the average accessibility time of a flat block.

[0133] In this embodiment, the obtained average reachable time of a block is divided into 7 categories:

[0134] 0≤T α <300, α is a Class 1 block

[0135] 300≤T α <360, α is a type 2 block

[0136] 360≤T α <420, α is 3 types of blocks

[0137] 420≤T α <480,α is 4 types of blocks

[0138] 480≤T α <540, α is the 5th type of block.

[0139] 540≤T α <600, α is 6 types of blocks

[0140] T α ≥600, α is 7 types of blocks)

[0141] Furthermore, in this embodiment, the areas of each type of block are summed up. Assuming that the total area of ​​type i block is S i ,but:

[0142]

[0143] The calculation of each type of coverage is mainly based on the proportion of each type of block area to the total area. The coverage rate of the i-th type of block Cov i for:

[0144]

[0145] After dividing the accessibility levels of the blocks within the area into different types, each type of block is visualized to intuitively display the range of accessibility levels after calculation, as shown in Table 2.

[0146] Table 2

[0147]

[0148]

[0149] In this embodiment, Figure 7 The total area of ​​the block in the example is 36203715.45, and the final visualization result is as follows Figure 7 .

[0150] The method for determining the coverage range of fire rescue stations based on blocks as units described in the above embodiments, the existing fire departments often fail to fully consider the actual conditions such as road network morphology and terrain when allocating and dispatching rescue resources, and cannot directly and effectively support the fire departments to carry out reasonable division of responsibility jurisdictions and dispatch of fire rescue resources, resulting in unreasonable and unscientific problems in the division of fire rescue responsibility jurisdictions and the dispatch of fire rescue resources. The present invention has a simple process and high accuracy. It adopts a block division standard that is more in line with practical applications to systematically divide the fire rescue accessibility of urban areas. By combining real-time traffic data, it accurately evaluates the fire rescue accessibility of each block, and performs grade division and reasonable division of the responsibility jurisdiction of each fire station. The present invention can not only more truly reflect the fire rescue response capabilities of different areas of the city under actual traffic conditions, but also help the fire department to reasonably divide the responsibility jurisdiction of each fire station, provide a scientific basis for the optimization of the layout of fire stations and the dispatch of fire rescue resources, and help improve the assessment accuracy and scientificity of urban fire safety management, and enhance the effectiveness of fire prevention and control.

[0151] Obviously, the embodiments described above are only preferred embodiments of the present invention, rather than all embodiments. The preferred embodiments of the present invention are shown in the accompanying drawings, but they do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific embodiments, or to perform equivalent replacements for some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of the present invention, directly or indirectly used in other related technical fields, is also within the scope of patent protection of the present invention.

Claims

1. A method for determining the coverage area of ​​a fire rescue station based on a block as a unit, characterized in that: The following steps are involved: S10, determining the calculation area and the fire station, obtaining the area boundary and the location of the fire station, obtaining the area base map, performing binarization processing on the area map, and picking up the outlines of each enclosed area except the road; S20, establishing a coordinate system for the binarized image, creating base points, calculating the boundary range of the block divided by roads according to the image contour, dividing the block units, and calculating and recording the expression of the boundary of each block unit; S30, determining the number and location of fire rescue demand points in the selected area, and preprocessing the collected data; S40, performing Mercator coordinate system conversion on the fire stations and demand points in the selected area, converting the longitude and latitude coordinates into pixel coordinates and mapping them to the drawing area of ​​the block boundary obtained by image recognition, and determining the block where the demand point is located; S50, calculating the time it takes for a fire truck to travel from each fire station to the demand point, and determining the weighted accessibility time from each fire station to each demand point in consideration of the travel time reduction coefficient; S60, calculate the average accessibility time of the entire block, divide the responsibility area of ​​each block unit, calculate the responsibility area of ​​each fire station, and generate a map for visual display; S70, calculating the average accessibility time of the entire block, dividing the block units into accessibility levels, calculating the area and coverage of each accessibility level, and generating a map for visual display.

2. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 1, characterized in that: In step S10, the target area to be calculated is clarified, the area boundary is obtained, the administrative boundary of the area is extracted through the online map API or the boundary coordinates of a specific area are manually selected, and it is assumed that there are z blocks within the selected range, and the numbers and geographic coordinates of the fire stations to be calculated in the area are recorded; After determining the calculation area, a custom map is made for this area, and the image is binarized, with all roads given white and other areas given black. After the custom map is enlarged to a size that can display the shape of the road network, the area to be calculated is intercepted.

3. The method for determining the coverage range of a fire rescue station based on a block as a unit according to claim 1, characterized in that: In step S20, the lower left vertex of the pixel in the lower left corner of the region range image is taken as (0,0), and the side length of 1 pixel is taken as a unit of 1. When traversing the turning points of the region boundary, the point with the smallest longitude and latitude coordinates is selected as the base point, and the longitude and latitude of the region boundary are traversed to find the point with the smallest longitude coordinate among all the turning points of the boundary. lon , whose longitude is lon min ; Traverse the point O with the smallest latitude coordinate among the turning points of the boundary of the region lat , whose latitude is lat min , create the base point O(lon min ,lat min ); Starting from the position (0,0), scan the image line by line within the image range to find the boundary of black pixels, track the boundary, and check the four neighboring pixels around the starting point. If there are four neighboring pixels with different colors, it is defined as the internal area boundary point P. i , after finding a black pixel, trace the contour along its boundary. After finding a path, continue to scan the image line by line, and repeat the above operation until all black pixel boundaries are found; Select the jump point as the starting point of the closed path, traverse all points on the contour, find the point pair with the largest distance, and use the last point in the point pair as the jump point; The closed path is simplified recursively to reduce redundant points in the path. According to each path after path simplification, the key points of all paths are output and recorded.

4. The method for determining the coverage range of a fire rescue station based on a block as a unit according to claim 3, characterized in that: In step S30, it is assumed that an area to be calculated has been determined, and there are m fire rescue demand points in the area, which include buildings, schools, and hospitals. The locations of the fire rescue demand points are obtained through on-site surveys, online maps, social media, government public data, and historical fire records. Fire rescue demand points are added to grid vertices within a certain number of meters of the natural geographical area in the area. At the same time, the collected data is preprocessed to remove duplicate points and correct erroneous data.

5. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 4, characterized in that: In step S40, each selected area boundary point, fire rescue demand point, and fire station is mapped in the drawing area using the Mercator coordinate system transformation, and the formula is as follows: Among them, X and Y represent the horizontal and vertical coordinates of the drawing area after mapping, respectively, G width and G height Respectively represent the width and height of the drawing area.

6. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 1, characterized in that: In step S50, the driving time of an ordinary car from a certain starting point to a destination is obtained by calling online maps and GIS services to obtain real-time traffic data. According to the Road Traffic Safety Law and the Fire Protection Law, when performing emergency tasks, other vehicles must give way to fire trucks. The driving time of fire trucks from fire stations to fire rescue demand points must be less than the driving time of normal cars. The reduction coefficient is set to β t , β t The value is generally less than or equal to 1. The travel time between the fire truck and the rth demand point is T' r , T pre is the time when the fire truck is ready to depart, then the actual driving time Tr of the fire truck from the corresponding fire station to the fire rescue demand point is as follows: Tr=β t ·T' r +T pre ,0<β t ≤1。 7. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 1, characterized in that: In step S60, for each fire station b, the driving time from b to all demand points in block α is calculated, where there are v fire rescue demand points in block α, and the weighted accessibility time from fire station b to all demand points in block α is averaged to obtain the overall average accessibility time of fire station b to block α. The formula is as follows: After obtaining the average overall accessibility time of all fire stations to block α, compare the average rescue time of all fire stations, select the fire station with the shortest average accessibility time as the main responsible fire station for block α, and then deduced the average overall accessibility time of other fire stations to block α. Take the fire station with the shortest average overall accessibility time of all fire stations to block α, and divide the range of block α into the responsibility area of ​​fire station b.

8. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 7, characterized in that: The area of ​​each unit is calculated using the Gaussian formula. For each fire station, the areas of all the blocks it is responsible for are added up. The responsibility areas of each fire station are then divided according to the scope of their jurisdiction. Different textures are given to distinguish the responsibility areas of each fire station, and they are visualized to intuitively show the scope of each fire station after calculation.

9. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 6, characterized in that: In step S70, the rescue accessibility of each block in the area is divided according to the calculated average accessibility time of all demand points in the block, and the expression is as follows: Assign each type of accessible block is the accessible block category, if If i is the i-type neighborhood, where i∈[1,n], ω i is the average accessibility time of a flat block.

10. The method for determining the coverage area of ​​a fire rescue station based on a block as a unit according to claim 9, characterized in that: The areas of each type of block are summed up, and the coverage rate of each type is calculated based on the proportion of the area of ​​each type of block to the total area. For each fire station, the areas of all the blocks it is responsible for are added up, and the various types of blocks are divided into accessibility levels. Each type of block is then visualized to intuitively show the range of accessibility levels after calculation.

Images