A method for determining the coverage range of a fire rescue station in a block unit

Abstract

The present application is suitable for the field of fire safety technology, and relates to a method for determining the coverable range of a fire rescue station with blocks as units, which has a simple process and high accuracy, adopts a block division standard more in line with actual application, systematically divides the fire rescue accessibility of urban areas, accurately evaluates the fire rescue accessibility of each block by combining real-time traffic data, and reasonably divides the responsibility jurisdiction of each fire station. The present application can not only more realistically reflect the fire rescue response capability of different regions of a 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 scheduling of fire rescue resources, and help to improve the evaluation accuracy and scientificity of urban fire safety management and the effectiveness of fire prevention and control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fire safety, and particularly relates to a method for determining the coverable range of a fire rescue station taking a block as a unit. BACKGROUND

[0002] In recent years, with the acceleration of urbanization, the building density and population concentration are increasing year by year, and the risk of fire occurrence is significantly increasing. This trend is particularly evident in old urban areas, commercial areas and high-rise building-dense areas. In dealing with fires, it is crucial for fire rescue forces to arrive at the fire site in a timely manner, and reasonable division of fire rescue responsibility areas and fire rescue resource scheduling are the fundamental basis for ensuring the effectiveness of fire safety management.

[0003] At present, when the fire department configures and schedules rescue resources, it often divides the fire rescue responsibility area in units of blocks, and the academic community mainly relies on fire rescue coverable range to guide the division of responsibility areas. The research on fire rescue coverable range mainly relies on traditional methods such as isochrone and boundary search. These methods often fail to fully consider actual conditions such as road network patterns and terrain, and cannot directly and effectively support the fire department to make reasonable division of responsibility areas and scheduling of fire rescue resources, resulting in the possibility of unreasonable and unscientific division of fire rescue responsibility areas and scheduling of fire rescue resources. Patent application with publication number CN113848881B provides a fire truck path planning method, system, terminal and storage medium. The method includes obtaining an environment model; based on the environment model, obtaining search boundary information and obstacle information, and using target-oriented rapid expansion tree search to obtain a global path; based on the global path, sending a control signal to the fire truck to make the fire truck move from the fire truck garage to the target point along the global path; receiving fixed obstacle information fed back during the fire truck's movement, and correcting the current pose of the fire truck based on the received fixed obstacle pose; receiving dynamic obstacle information fed back during the fire truck's movement, performing obstacle motion collision prediction based on the received dynamic obstacle, and determining whether to perform local path planning based on the prediction result, and updating the global path using local path planning. This patent also uses the method of boundary search to realize the management of fire resource distribution and fire resource deployment, and has the same disadvantages as the prior art.

[0004] Therefore, how to provide a method for determining the coverable range of a fire rescue station taking a block as a unit to scientifically divide the fire rescue responsibility area, reasonably configure rescue resources and improve the utilization rate of fire resources is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application aims to provide a fire rescue station coverage range determination method based on blocks, so as to solve the problems of unreasonable and unscientific division of fire rescue responsibility areas and scheduling of fire rescue resources in the prior art.

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

[0007] The present application provides a fire rescue station coverage range determination method based on blocks, comprising the following steps:

[0008] S10, determine the calculation area and the fire station, obtain the area boundary and the fire station position, acquire the area map, perform binaryzation processing on the area map, and pick up the contour of each enclosed area except the road; S20, establish a coordinate system for the binaryzation image, create a base point, calculate the block boundary range divided by the road according to the image contour, divide the block unit, and calculate and record the expression of the block unit boundary; S30, determine the number and position of the fire rescue demand points in the selected area, and pre-process the collected data; S40, perform Mercator coordinate system conversion on the fire station and demand point in the selected area, convert the latitude and longitude coordinates into pixel coordinates, and map to the drawing area of the block boundary obtained by image recognition, and judge the block where the demand point is located; S50, calculate the time of the fire truck from each fire station to the demand point, determine the weighted accessibility time of each fire station to each demand point in consideration of the driving time reduction coefficient; S60, calculate the overall accessibility average time of the 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, calculate the overall accessibility average time of the block, divide the accessibility level of the block unit, calculate the accessibility level area and coverage rate, and generate a map for visual display.

[0009] Further, in the step S10, the target area for calculation is determined, the area boundary is acquired, the area administrative boundary is extracted through an online map API or the boundary coordinates of a certain area are manually selected, there are z blocks in the selected range, and the number and geographical coordinate position of the fire stations to be calculated in the area are recorded;

[0010] After the calculation area is determined, a self-defined map is performed on the area, binaryzation processing is performed on the image, all roads are assigned white color and other areas are assigned black color, the self-defined map is enlarged to display the road network shape, and 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's image is taken as (0,0), and the side length of one pixel is taken as 1. When traversing the turning points of the region's boundaries, the point with the smallest latitude and longitude coordinates is selected as the base point. The latitude and longitude of the region's boundaries are traversed to find the point O with the smallest longitude coordinate among all boundary turning points. lon Its longitude is lon min ; Traverse the boundary turning points of this region and find the point O with the smallest latitude coordinate. lat Its latitude is lat min Create the base point O (lon) min ,lat min );

[0012] Starting from 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, define it as the boundary point P of the internal region. i Once a black pixel is found, its contour is traced along its boundary. After finding a path, the image is scanned line by line until all black pixel boundaries have been 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 second point in the point pair as the jump point.

[0014] The closed path is simplified by recursion, reducing redundant points in the path. Based on the simplified path, the key points of all paths are output and recorded.

[0015] Furthermore, in step S30, assuming the area to be calculated has been determined, there are m fire rescue demand points in the area. 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, public data, and historical fire records. Fire rescue demand points are added to the grid vertices within a certain number of meters of the natural geographical area of ​​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 within the drawing area using Mercator coordinate system transformation, as shown in the following formula:

[0017]

[0018] Where X and Y represent the upper x-coordinate and y-coordinate of the mapped plotting area, respectively, and G... width and G height These represent the width and height of the drawing area, respectively.

[0019] Further, in step S50, the travel time of a general car from a starting point to a terminal point is called by using online map and GIS service to obtain real-time traffic data. According to the Road Traffic Safety Law and the Fire Control Law, other vehicles need to give way to fire vehicles when performing emergency tasks, and the travel time of the fire vehicle from the fire station to the fire rescue demand point is less than the travel time of the normal car. A reduction coefficient β is set t , the travel time of the fire vehicle from the fire station to the rth demand point is T' r , T pre is the time when the fire vehicle is ready to start, and the actual travel time Tr of the fire vehicle 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] Further, in step S60, for each fire station b, the travel time of b to all demand points in the block a is calculated, where there are v fire rescue demand points in the block a. The weighted accessibility time of the fire station b to all demand points in the block a is averaged to obtain the overall accessibility average time of the fire station b to the block a The formula is as follows:

[0022]

[0023] After obtaining the overall accessibility average time of all fire stations to the block a, the average rescue time of all fire stations is compared, and the fire station with the shortest average accessibility time is selected as the main responsible fire station of the block a. Similarly, the overall accessibility average time of other fire stations to the block a is obtained, and the fire station with the smallest overall accessibility average time to the block a is selected, and the range of the block a is divided into the responsibility jurisdiction of the fire station b.

[0024] Further, the area of each unit is calculated by using the Gaussian formula. For each fire station, the areas of all blocks under its responsibility are added, and then the responsibility jurisdiction ranges of various fire stations are divided to divide the responsibility jurisdiction areas of various fire stations. Different textures are assigned to the responsibility jurisdiction areas of various fire stations for differentiation and visualization, so as to intuitively display the attribution ranges of various fire stations after calculation.

[0025] Further, in step S70, the rescue accessibility of each block in the region is divided according to the average time of the accessibility of all demand points in the block obtained by calculation, and the expression is as follows:

[0026]

[0027] assigning each type of accessible block For the accessible block category, if is the i-th block, where i∈[1,n], ω i is the average time of the flat block accessibility.

[0028] Further, the area of each type of block is summed up, and the calculation of the coverage rate of each type is determined according to the proportion of the area of each type of block in the total area. For each fire station, the area of all blocks under its responsibility is accumulated, and after the accessibility level of each type of block is divided, the visualization processing of each type of block is performed to intuitively display the range of each accessibility level after calculation.

[0029] Compared with the prior art, the method for determining the coverable range of the fire rescue station uniting the blocks provided by the application has at least the following beneficial effects:

[0030] The existing fire department often fails to fully consider the actual conditions such as road network form and terrain when performing rescue resource allocation and scheduling, and cannot directly and effectively support the fire department to perform reasonable responsibility division and fire rescue resource scheduling, resulting in that the division of the fire rescue responsibility division and the scheduling of the fire rescue resource may be unreasonable and unscientific. The process of the application is simple and has high accuracy, adopts a block division standard more in line with actual application, performs systematic division on the fire rescue accessibility of the urban area, accurately evaluates the fire rescue accessibility of each block by combining real-time traffic data, and performs level division on the blocks and reasonably divides the responsibility division of each fire station. The application can not only more truly reflect the fire rescue response capability of different regions of the city under actual traffic conditions, but also help the fire department to reasonably divide the responsibility division of each fire station, provide a scientific basis for the optimization of the fire station layout and the scheduling of the fire rescue resource, and help to improve the evaluation accuracy and scientificity of the urban fire safety management and enhance the effectiveness of fire prevention and control. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the scheme of the application, the drawings needed in the following embodiment description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 A flowchart of a method for determining the coverable range of a fire rescue station uniting blocks provided by an embodiment of the application is shown in the figure.

[0033] Figure 2The area range map determined by calculation in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application;

[0034] Figure 3 The area range map determined by calculation in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application; Figure 2 The value map;

[0035] Figure 4 The internal area boundary map in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application;

[0036] Figure 5 The internal area boundary map in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application;

[0037] Figure 6 The internal area boundary map in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application;

[0038] Figure 7 The internal area boundary map in the block unit fire rescue station coverable range determination method provided by the embodiment of the present application; DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present application can be more thoroughly and completely understood.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application.

[0041] The embodiment of the present application provides a block unit fire rescue station coverable range determination method, which is applied to the research and application process of fire rescue coverable range. The block unit fire rescue station coverable range determination method comprises the following steps:

[0042] S10, determine the calculation area and the fire station, obtain the area boundary and the fire station position, acquire the area map, carry out binaryzation processing to the area map, and pick up the contour of each enclosed area except the road; S20, establish a coordinate system for the binaryzation image, create a base point, calculate the street block boundary range divided by the road according to the image contour, and divide the street block unit to calculate and record the expression of the boundary of each street block unit; S30, determine the number and position of the fire rescue demand points in the selected area, and pretreat the collected data;

[0043] S40, carry out the Mercator coordinate system conversion on the fire station and demand point in the selected area, convert the longitude and latitude coordinates into pixel coordinates, and map to the drawing area of the street block boundary obtained by image recognition to judge the street block where the demand point is located; S50, calculate the time of the fire truck from each fire station to the demand point, determine the weighted accessibility time of each fire station to each demand point in the case of considering the driving time reduction coefficient; S60, calculate the overall accessibility average time of the street block, divide the responsibility jurisdiction of each street block unit, calculate the responsibility jurisdiction area of each fire station, and generate a map for visual display; S70, calculate the overall accessibility average time of the street block, divide the accessibility level of the street block unit, calculate the area and coverage rate of each accessibility level, and generate a map for visual display.

[0044] The method has simple flow and high accuracy, adopts a street block division standard more in line with actual application, performs systematic division on the fire rescue accessibility of the urban area, accurately evaluates the fire rescue accessibility of each street block by combining real-time traffic data, and reasonably divides the responsibility jurisdiction of each fire station.

[0045] In order to enable personnel in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings.

[0046] The present application provides a fire rescue station coverable range determination method taking a street block as a unit, which is applied to the research and application process of the fire rescue coverable range, combines the real-time traffic data and the street block division standard, and determines the coverable range of each fire rescue station. Figures 1 to 7 The fire rescue station coverable range determination method taking a street block as a unit in the embodiment includes the following steps:

[0047] S10, determine the calculation area and the fire station, obtain the region boundary and the fire station position, acquire the region map, and perform binaryzation processing on the region map to pick up the contour of each enclosed region except the road.

[0048] Specifically, the target region to be calculated needs to be determined, which can be a pre-set urban area or an arbitrarily defined range. Then, the region boundary is obtained, which can be achieved by extracting the administrative boundary of the region through an online map API or manually selecting the boundary coordinates of a certain region according to actual needs. Assuming that there are z blocks within the selected range, the region with a lower latitude usually provides more accurate calculation results because the curvature of the earth affects the accuracy of the coordinate system conversion at a higher latitude, thereby affecting the accuracy of the calculation. At the same time, the number and geographic coordinate position of the fire stations within the region that need to be calculated are recorded.

[0049] In this embodiment, a region to be calculated in a certain city is selected, and the region range is as shown in Figure 2 At the same time, four fire stations need to be calculated: 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] Further, in this embodiment, after determining the calculation region, the region is subjected to binaryzation processing on the image, all roads are assigned white color, and other regions are assigned black color. After enlarging the customized base map to display the road network shape, the region to be calculated can be intercepted with the help of a high-definition display. If the selected range is too large, relevant tile maps can also be downloaded and merged.

[0051] In this embodiment, the region range map is subjected to binaryzation, and the region range image involved is as shown in Figure 3

[0052] S20, establish a coordinate system for the binaryzation image, create a base point, calculate the block boundary range divided by the road according to the image contour, divide the block unit, and calculate and record the expression of the block unit boundary.

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

[0054] In this embodiment, the coordinate system and the unit are set, the left lower corner coordinate is taken as (0, 0), and the edge length of 1 pixel is taken as 1. Figure 3 ​​

[0055] Further, in this embodiment, the base point is created to determine a reference point in the map area, facilitating subsequent mapping of coordinates. When traversing the boundary turning points of the area, the point with the smallest latitude and longitude coordinates is selected as the base point. The reason for selecting the smallest latitude and longitude is to ensure that the base point is at the lower left of the map, consistent with the common coordinate system (such as the Cartesian coordinate system), thereby simplifying subsequent calculation and mapping operations. All boundary turning points of the area are traversed to find the point O with the smallest longitude lon , whose longitude is lon min . Similarly, the point O lat with the smallest latitude is found by traversing the boundary turning points of the area, whose latitude is lat min . Accordingly, the base point O(lon min , lat min ) is created.

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

[0057] Further, in this embodiment, starting from the (0, 0) position, the image is scanned row by row within the image range to find the boundary of black pixels, and the boundary is tracked. The four neighboring pixels around the starting point are checked. If the colors of the four neighboring pixels are different, it is defined as an internal area boundary point P i , as shown in Figure 4 .

[0058] After finding a certain black pixel, the contour tracking is performed along its boundary. During tracking, each step is called a "unit step", which represents moving from the current pixel point to the next turning point. The rule is that the left side is white and the right side is black. The unit step can only move in four basic directions: up, down, left, and right (as shown in Figure 4 ). The unit step path is defined as the shortest path from a pixel point to an adjacent pixel point in the four directions. The contour of each black region is composed of a series of unit steps, forming a complete "unit step path". If there are k complete "unit step paths" in the region, the sum of these paths constitutes the contour of the entire image. After finding a path, the image is scanned row by row, and the above operation is repeated until all black pixel boundaries are found.

[0059] Further, in the embodiment, the 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, which generally corresponds to the part of the shape mutation in the image contour, for example, the point where the edge of the contour changes sharply, traverse all points on the contour: calculate the Euclidean distance between each point and its previous point, and then compare the distances of the points in the same "unit step path": find the point pair with the maximum distance, and take the latter point in the point pair as the jump point.

[0060] For the alpha path (P0→P1→P2→P3→...→P n-1 →P0), where each point P i =(x i ,y i ), calculate the Euclidean distance d i between all two adjacent points P i-1 and P i :

[0061]

[0062] Find the maximum distance and its index:

[0063] d max =max(d1,d2,...,d n-1 )j=argmax(d1,d2,...,d n-1 )(find the index of the maximum distance).

[0064] Then the jump point of the alpha path (P0→P1→P2→P3→...→P n-1 →P0) is: J=P j . The determined jump point J is taken as the starting point of the closed path, and then a terminal point T needs to be determined, which is the point farthest from the jump point J, which can be achieved by calculating the Euclidean distance between each contour point and the jump point.

[0065] For each point P i in the closed path, calculate its distance from the jump point J:

[0066]

[0067] Find the maximum distance d max and its corresponding point T:

[0068]

[0069] Further, in the embodiment, the closed path is simplified by recursively reducing the redundant points in the path while ensuring that the shape of the path does not change significantly.

[0070] To handle closed paths, define the α path (P0→P1→P2→P3→...→P n-1 →P0) The starting point J is the jump point (x) on the closed path. j ,y j ), T(x k ,y k Let α be the point that is furthest from point J by a straight line distance d. Decompose the closed path α into α, ... and

[0071] Based on the starting point P j With the endpoint P k Find the path from the coordinates The expression for a straight line:

[0072] Ax + By + C = 0.

[0073] Where A = y j -y k B = x k -x j C = x j y j -x k y j +y k -y j traversing the path For all intermediate points, calculate the points P on the path in sequence. i distance d i :

[0074]

[0075] 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 is considered to be... m It is a path The important key points need to be preserved, so the path become and

[0076] Now we need to obtain the path. and The linear expression, and then the path Traverse all points in the path to the path Find the distance to the path. For the point with the largest distance, further determine the threshold ξ for that point; if the distance is within the path... If the point with the largest distance is still considered a crucial point, it will continue to be retained, and the path will be further decomposed until all intermediate points of the path are less than the set threshold ξ. and path The same operation is performed.

[0077] Further, in this embodiment, according to each path after the path simplification processing, the key points (including the starting point, the ending point and the intermediate key nodes) of these paths are output and recorded, each path corresponds to a line segment set, and the line segments can be expressed by mathematical expressions. In this step, all generated paths are numbered and their specific geometric information such as the starting point, ending point coordinates and expressions of the line segments are recorded.

[0078] S30, determine the number and location of fire rescue demand points in the selected area, and preprocess the collected data.

[0079] Specifically, it is assumed that the area to be calculated has been determined, and there are m fire rescue demand points in the area, wherein the fire rescue demand point refers to a potential fire risk point such as a building, a school, a hospital, etc. The location of the fire rescue demand point is obtained through field investigation, online map, social media, public data, historical fire record, etc. At the same time, in order to ensure the full coverage of the area, the fire rescue demand points are added at the grid vertices of the area except the natural geographical area range such as the mountain foot and the river, and the collected data is preprocessed to remove duplicate points and correct error data. x ×d y meters, and the collected data is preprocessed to remove duplicate points and correct error data.

[0080] 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 field investigation to ensure the accuracy of the fire stations. At the same time, the location information of the demand points is collected through field investigation, viewing online maps such as Gaode map, public data, historical fire record, etc. The collected demand point data is preprocessed to remove duplicate points and correct error latitude and longitude information, etc. to ensure the accuracy and effectiveness of the data. Finally, there are 12282 fire rescue demand points in the area.

[0081] S40, Mercator coordinate system conversion is performed on the fire station points and demand points of the selected area, the latitude and longitude coordinates are converted into pixel coordinates and mapped to the drawing area of the block boundary obtained by image recognition, and the block where the demand point is located is judged.

[0082] Specifically, each geographical object (selected area boundary point, fire rescue demand point, fire station) is mapped in the drawing area by using Mercator coordinate system conversion. In the formula, X and Y represent the horizontal coordinate and vertical coordinate in the mapped drawing area, respectively.

[0083]

[0084] where G width and G height represent the width and height of the plot area, respectively.

[0085] In this embodiment, Figure 2 The left-bottom corner of the plot area has the longitude and latitude coordinates of (113.832545, 22.722021), and the right-top corner has the coordinates of (113.901947, 22.831542). The width of the plot area is 12914 pixels, and the height is 22097 pixels. It is known that there are four fire stations in the vicinity: fire station 1 has the coordinates of (113.873361, 22.783574), fire station 2 has the coordinates of (113.876401, 22.789415), fire station 3 has the coordinates of (113.875334, 22.773865), and fire station 4 has the coordinates of (113.871003, 22.780899). Therefore, the coordinates of fire stations 1, 2, 3, and 4 in the plot area are (7485, 12347), (7698, 13446), (7631, 10885), and (7250, 12070), respectively.

[0086] Further, in this embodiment, a set P = {P1, P2,..., P z} is defined, where each element represents a polygon of a block and contains the coordinates of all vertices of the polygon. The polygon surrounded by the block a is P α = {(x α1 ,y α1 ), (x α2 ,y α2 ),..., (x αz ,y αz )}. All demand points only need to determine whether the point is located in the first intersected polygon.

[0087] Suppose the pixel coordinates of a point P are (x p ,y p ). A horizontal ray is selected to be emitted to the right, i.e., from the point P to (+∞, y p ). Suppose that the block a is the first polygon intersected by the ray. For each edge of the block a, the ray is determined to be intersected or not according to the following conditions.

[0088] Suppose that the coordinates of the two end points of the i-th edge of a are (x αi ,y αi ) and (x αi+1 ,y αi+1 ). The condition for the ray to be intersected with the edge is:

[0089] The edge is within the y range of the ray:

[0090] (y αi >y αp ) ≠ (yαi+1 <y αp )。

[0091] If the above conditions are met, the x coordinate x intersect ,y intersect ) of the intersection point (x intersect is calculated:

[0092] Then, the interference of special cases is excluded:

[0093]

[0094] 1. Vertex check, that is, the intersection point of the ray and the vertex of the polygon should not be calculated, if:

[0095]

[0096] The point needs to be skipped.

[0097] 2. Coincidence edge check, that is, the ray and an edge of the polygon coincide, and this edge should be ignored.

[0098]

[0099] The point needs to be skipped.

[0100] For each edge, the above intersection point condition check is performed, and the number of intersection points is checked, and if the number of intersection points is odd, the point is in the polygon; if the number of intersection points is even, the point is outside the polygon, that is, let count be the number of intersection points of the ray and the edges of the polygon, which can be expressed as:

[0101]

[0102] Where I i is an indicator function, which is defined as follows:

[0103]

[0104] Finally, it is judged that if the number of intersection points is odd, the point is in the first intersecting polygon; if the number of intersection points is even, the point is outside the polygon.

[0105] S50, calculate the time of the fire truck from each fire station to the demand point, and determine the weighted accessibility time of each fire station to each demand point in consideration of the travel time reduction coefficient.

[0106] Specifically, by calling online map, GIS and other services, the travel time T′ bcThe driving time from the fire station b to the demand point c, according to the Road Traffic Safety Law and the Fire Law, other vehicles need to give way to the fire vehicle when performing emergency tasks, so the driving time T' of the fire vehicle from the fire station to the fire rescue demand point bc is less than the driving time of a normal car, set a reduction factor β t .

[0107] The driving time T' of the fire vehicle from the fire station to the rth demand point r can be calculated by the formula T pre is the preparation time of the fire vehicle (in seconds), and the actual driving time Tr of the fire vehicle from the corresponding fire station to the fire rescue demand point.

[0108] Tr = β t · T' r + T pre , 0 < β t ≤ 1.

[0109] In this embodiment, the reduction factor β t is 0.9, and the preparation time T pre is 60 seconds.

[0110] Further, in this embodiment, a period of time is selected as the calculation period, and u scenes are set in the period, the corresponding time point in the ith estimated scene is t i , and the driving time of the fire station b to the fire demand point c is Tr i,bc , and the weighted driving time T bc of the fire station b to the demand point c can be obtained by using the similar integral solution idea.

[0111]

[0112] S60, calculate the overall accessibility average time of the block, divide the responsibility area of each block unit, calculate the responsibility area area of each fire station, and generate a map for visual display.

[0113] Specifically, for each fire station b, the driving time of the fire station b to all demand points in the block a is calculated, where there are v fire rescue demand points in the block a, and the weighted accessibility time of the fire station b to all demand points in the block is averaged to obtain the overall accessibility average time of the fire station b to the block a

[0114]

[0115] After obtaining the average time of overall accessibility of all fire stations to the block, the average rescue time of all fire stations is compared, and the fire station with the shortest average time of overall accessibility is selected as the main responsible fire station of the block. The average time of overall accessibility of other fire stations to the block is also obtained, and the fire station with the smallest average time of overall accessibility to the block is selected, and the range of the block is divided into the responsibility area of the fire station.

[0116] In this embodiment, since the number and position of fire stations have a direct impact on the fire rescue level of an area, the position and number of fire stations in the area are determined through on-site investigation to ensure the accuracy of the fire stations. At the same time, the position information of demand points is collected through on-site investigation, online maps such as Gaode map, public data, historical fire records and other ways, and the collected demand point data is preprocessed to remove duplicate points, correct wrong latitude and longitude 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. It is assumed that there are 10 fire rescue demand points in the block a, and the driving time (unit: second) of the corresponding demand points to the straight-line distance of the nearest three fire stations A, B, C, D is shown in Table 1:

[0117] Table 1

[0118]

[0119] According to the rules: T Aα < T Bα < T Cα < T Dα , it is considered that the block a is the responsibility area of the fire station A.

[0120] Further, in this embodiment, the area of each unit is calculated by using the Gaussian formula. Assuming that the existing path (P0→P1→P2→P3→...→P n-1 →P0) corresponds to the block a, then the area of the block S α is

[0121]

[0122] Further, in this embodiment, for each fire station, the areas of all blocks responsible by the fire station are added, and the block set responsible by a certain fire station is set as {S e1 , S e2 ,..., S en}, then the responsibility area of the fire station is the sum of the areas of these blocks:

[0123]

[0124] wherein, S e总S is the area of the responsibility area of the fire station ei S is the area of each block.

[0125] According to the responsibility area range surrounded by each fire station, the responsibility area of each fire station is divided, and different textures are assigned to each fire station responsibility area to visualize and intuitively display the calculated range of each fire station.

[0126] In this embodiment, the total area of the block is calculated as 36203715.45, of which the area belonging to fire station 1 is 16695605.73, the area belonging to fire station 2 is 8881513.903, the area belonging to fire station 3 is 5603574.144, and the area belonging to fire station 4 is 5023021.674. Figure 2 Figure 6 The visualization result is shown in

[0127] S70, calculate the average time of the overall accessibility of the block, divide the block unit into accessibility levels, calculate the area of each accessibility level and the coverage rate, and generate a map for visualization.

[0128] Specifically, according to the average time of the accessibility of all demand points in the block The rescue accessibility of each block in the area is divided.

[0129]

[0130] Each type of accessible block is assigned to the accessible block category, if i is the i-th block, where i∈[1,n], ω i is the average time of the accessibility of the flat block.

[0131] In this embodiment, the block accessibility average time is divided into 7 categories:

[0132]

[0133] Further, in this embodiment, the area of each type of block is summed, and the total area of the i-th block is assumed to be S i Then:

[0134]

[0135] The calculation of the coverage rate of each type is mainly determined according to the proportion of the area of each type of block in the total area, and the coverage rate of the i-th block is Cov i is:

[0136] ​

[0137] After the obtained each type of block is classified according to the block accessibility in the region, the visualization processing is performed on each type of block to intuitively show the range of each accessibility level after the calculation, as shown in Table 2.

[0138] Table 2

[0139]

[0140]

[0141] In the embodiment, the calculation region is calculated, the total area of the embodiment block is 36203715.45, and the finally obtained visualization result is as shown in Figure 7 . Figure 7 .

[0142] The fire rescue station coverage range determination method based on blocks described in the above embodiment, the existing fire department often fails to fully consider the actual situation of road network form and terrain when performing rescue resource allocation and scheduling, and cannot directly and effectively support the fire department to perform reasonable responsibility jurisdiction division and fire rescue resource scheduling, resulting in that the division of fire rescue responsibility jurisdiction and the scheduling of fire rescue resources may be unreasonable and unscientific. The process of the present application is simple and has high accuracy, adopts a block division standard more in line with actual application, performs systematic division on the fire rescue accessibility of the urban region, accurately evaluates the fire rescue accessibility of each block by combining real-time traffic data, and performs grade division on the responsibility jurisdiction of each fire station. The present application can not only more truly reflect the fire rescue response capability of different regions 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 scheduling of fire rescue resources, and help to improve the evaluation accuracy and scientificity of urban fire safety management and enhance the effectiveness of fire prevention and control.

[0143] Obviously, the above-described embodiments are only the preferred embodiments of the present application, but not all the embodiments. The preferred embodiments of the present application are given in the drawings, but do not limit the patent scope of the present application. The present application can be realized in many different forms, and conversely, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some technical features. Any equivalent structure made by using the contents of the present application specification and drawings, directly or indirectly applied to other related technical fields, is also within the patent protection scope of the present application.

Claims

1. A method for determining the coverage area of ​​a fire and rescue station based on a street block, characterized in that, Includes the following steps: S10. Determine the calculation area and fire station, obtain the area boundary and fire station location, acquire the area map, perform binarization on the area map, and pick the outlines of each enclosed area except for roads. In step S10, the target area for calculation is defined, the area boundary is obtained, the administrative boundary of the area is extracted through an online map API or the boundary coordinates of a certain area are manually selected, and the number and geographical coordinates of the fire stations to be calculated in the area are recorded. After determining the calculation area, a custom map is created for this area, and the image is binarized. All roads are given white, and other areas are given black. The custom map is then enlarged to show the shape of the road network, and the area to be calculated is then cropped. S20. Establish a coordinate system for the binarized image, create base points, calculate the boundary range of the blocks divided by roads based on the image contour, divide the blocks into blocks, calculate and record the expression of the boundary of each block. In step S20, the lower left vertex of the pixel at the lower left corner of the region image is taken as (0,0), and the side length of 1 pixel is taken as 1. When traversing the turning points of the region boundary, the point with the smallest latitude and longitude coordinates is selected as the base point. The latitude and longitude coordinates of the region boundary are traversed to find the point O with the smallest longitude coordinate among all boundary turning points. lon Its longitude is lon min ; Traverse the boundary turning points of this region and find the point O with the smallest latitude coordinate. lat Its latitude is lat min Create the base point O (lon) min ,lat min ); Starting from 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, define it as the boundary point P of the internal region. i Once a black pixel is found, its contour is traced along its boundary. After finding a path, the image is scanned line by line until all black pixel boundaries have been 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 second point in the point pair as the jump point. The closed path is simplified by recursion, reducing redundant points in the path. Based on the simplified path, the key points of all paths are output and recorded. S30. Determine the number and location of fire rescue demand points within the selected area, and preprocess the collected data; S40. Perform Mercator coordinate system transformation on the selected fire stations and demand points, convert latitude and longitude coordinates into pixel coordinates, and map them to the drawing area of ​​the street boundary obtained by image recognition to determine the street where the demand point is located. S50. Calculate the time for fire trucks to travel from each fire station to the demand point, and determine the weighted accessibility time of each fire station to each demand point after considering the travel time reduction factor. S60. Calculate the average time for overall accessibility of the block, divide the responsibility area of ​​each block unit, calculate the responsibility area of ​​each fire station, and generate a map for visualization. S70. Calculate the average time for overall accessibility of the block, classify the block units into accessibility levels, calculate the area and coverage of each accessibility level, and generate a map for visualization.

2. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 1, characterized in that, In step S30, it is assumed that the area to be calculated has been determined, and there are m fire rescue demand points in the area. 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, public data, and historical fire records. Fire rescue demand points are added to the grid vertices within a certain number of meters of the natural geographical area of ​​the area. At the same time, the collected data is preprocessed to remove duplicate points and correct erroneous data.

3. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 2, characterized in that, In step S40, each selected area boundary point, fire rescue demand point, and fire station is mapped onto the drawing area using Mercator coordinate system transformation, as shown in the following formula: Where X and Y represent the upper x-coordinate and y-coordinate of the mapped plotting area, respectively, and G... width and G height These represent the width and height of the drawing area, respectively.

4. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 1, characterized in that, In step S50, the travel time of a regular car from a 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, other vehicles must give way to fire trucks when performing emergency tasks. The travel time of a fire truck from the fire station to the fire rescue demand point is less than the travel time of a regular car. A reduction factor of β is set. t The travel time for a fire truck from the fire station to the r-th demand point is T'. r T pre If the time is when the fire truck is ready to depart, then the actual travel time Tr 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。 5. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 1, characterized in that, In step S60, for each fire station b, the travel time from b to all demand points within block α is calculated, where there are v fire rescue demand points within block α. The weighted accessibility time of fire station b to all demand points within block α is averaged to obtain the overall average accessibility time of fire station b to that 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 fire station responsible for block α, and so on, calculate the average overall accessibility time of other fire stations to block α, select the fire station with the smallest average overall accessibility time of all fire stations to block α, and divide the area of ​​block α into the responsibility area of ​​fire station b.

6. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 5, characterized in that, The area of ​​each unit is calculated using the Gaussian formula. For each fire station, the areas of all the blocks under its jurisdiction are summed up. Then, based on the responsibility area enclosed by each fire station, the responsibility areas of each fire station are divided. Different textures are assigned to the responsibility areas of each fire station to distinguish them and make them visual, so as to intuitively show the calculated scope of each fire station.

7. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 4, characterized in that, In step S70, the accessibility of rescue services for each block within the area is divided based on the average time of accessibility to all demand points within the block, as shown in the following expression: Assigning access to various types of neighborhoods For the accessible street category, if If ω is i, then it is block i, where i∈[1,n], and ω i Average access time for flat street blocks.

8. The method for determining the coverage area of ​​a fire and rescue station based on a street block as described in claim 7, characterized in that, The areas of various types of blocks are summed, and the coverage rate of each type is determined 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 under its responsibility are summed. After the accessibility levels of the obtained blocks of each type are divided, the blocks of each type are visualized to intuitively show the range of each accessibility level after calculation.

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