Method for calculating average building height and determining landform type using field measured data

Abstract

The present invention relates to a method for calculating the average building height and determining the landform category using field measured data. The method includes obtaining the heights of all buildings and the coordinates of building outline points in the area to be evaluated by aerial remote sensing mapping, performing quadrilateral regularization segmentation processing on the building plane to obtain an initial surface area, gridding the area to be evaluated into grid units, and assigning the height corresponding to the initial surface area to the height of the grid unit, taking a fan-shaped wind direction influence area inside the area to be evaluated, and obtaining the average building height by using the height of the grid unit in the wind direction influence area, and obtaining the ground roughness category of the area to be evaluated by the average building height. The present invention proposes a method for quantitatively determining the landform roughness category, which is suitable for determining the landform roughness of sites with uneven building heights and different site categories, and makes up for the deficiency that the landform roughness category in the load specification is difficult to determine due to the qualitative method used to describe the landform roughness category.

Description

Technical Field

[0001] The invention belongs to a landform category determination method in the field of wind engineering, and in particular relates to a method for calculating average building height and determining landform category using field measured data. Background Art

[0002] The wind load on building structures depends on many factors, among which the type of topographic roughness plays a very important role. In the Code for Loads on Building Structures GB 50009-2012, the ground roughness is divided into four categories: A, B, C, and D. The applicable objects of the classification are: Class A (offshore sea surface and islands, coasts, lake shores and desert areas), Class B (fields, villages, jungles, hills and towns with relatively sparse houses), Class C (urban areas with dense buildings), and Class D (urban areas with dense buildings and high houses), so that the wind resistance analysis of structures can be carried out accordingly. However, due to the use of qualitative text descriptions, it is easy to be ambiguous when determining the type of topographic roughness, and there is a lack of quantitative judgment methods. At the same time, the appendix of the Code for Loads on Building Structures GB50009-2012 also proposes an approximate relationship between topographic roughness and average height. The average height of buildings within the windward semicircle of 2km is less than 9m, which is Class B, when the average height is greater than 9m but less than 18m, it is Class C, and when it is greater than 18m, it is Class D. Similarly, this expression cannot be determined because it is impossible to accurately calculate the average height. At the same time, different wind directions are likely to have different landform features.

[0003] For the ground roughness coefficient, previous studies are usually based on uniformly arranged houses, which has certain limitations in applicability to the current complex building environment. In the existing technology, the American ASCE specification uses morphometric method to study landform categories. Although this is the most widely recognized method internationally, this method is based on the results of uniformly arranged houses.

[0004] However, the actual distribution of houses is complicated, generally including super high-rises, high-rises, bungalows, green spaces and water systems, so the above morphological measurement method is no longer applicable. That is, the current landforms in cities and villages at home and abroad are complex, usually a combination of multiple landforms and multiple building types, which makes it difficult to determine the landform type. The existing technology lacks a new method for quantitatively determining the landform roughness category, which is used to determine the landform conditions of the site, such as the complex changes in building height and site type. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a method for calculating the average height of buildings and determining the landform category using field measured data. The method is a method for calculating the average height of buildings based on remote sensing technology combined with city maps. The method is suitable for determining the landform roughness of sites with uneven building heights and different site categories, which makes up for the deficiency of using qualitative methods to describe the landform roughness category in the load specification, which makes it difficult to determine.

[0006] The technical solution adopted by the present invention is:

[0007] The method for calculating the average building height and determining the landform category using field measured data includes the following steps:

[0008] Step 1: First, use aerial remote sensing to obtain the basic information of all buildings in the area to be evaluated. Then, obtain the building plan of each building through the basic information of the building. Perform quadrilateral regularization segmentation on the building plan to obtain the initial area of ​​each building, and determine the building height corresponding to each initial area.

[0009] Step 2: Divide the area to be evaluated into grids according to the preset grid unit size to form a number of grid units, each grid unit corresponds to a height, and assign the height corresponding to each initial surface area to the height corresponding to the grid unit inside the initial surface area, and the height corresponding to the grid unit outside the initial surface area is zero;

[0010] Step 3: Correct the height of the grid unit: extend the initial domain outward on the initial domain with its own height as the extension distance to form a new domain as the simulation domain. The height corresponding to each simulation domain is the height corresponding to the initial domain before the extension. Then, use the height corresponding to each simulation domain to reassign the height corresponding to each grid unit.

[0011] Step 4: Take a fan-shaped area at any position in the area to be evaluated with a preset central angle as the wind direction influence area, the vertex and radius of the wind direction influence area are respectively the center and radius of the area to be evaluated, the wind direction of the wind direction influence area is perpendicular to the tangent line of the arc of the wind direction influence area, and take the average value of the grid unit height in the wind direction influence area as the average building height under the wind direction corresponding to the wind direction of the wind direction influence area;

[0012] Step 5: Repeat step 4 multiple times to obtain the average building heights under different wind directions, and determine the ground roughness category of the area to be evaluated based on the minimum value of the average building heights under all wind directions. The ground roughness category is Class A ground roughness category, Class B ground roughness category, Class C ground roughness category, or Class D ground roughness category. The wind load of the building is calculated using different ground roughness categories, thereby realizing the quantitative calculation of the wind load.

[0013] The ground roughness category is determined based on the building density and building height of the area to be evaluated. Class D ground roughness category indicates that the buildings in the area to be evaluated are densely distributed and the building heights are high, while Class A ground roughness category indicates that the buildings in the area to be evaluated are sparsely distributed and the building heights are low.

[0014] The step 1 is specifically as follows: first, a satellite remote sensing image of the area to be evaluated is taken by aerial remote sensing mapping, and at the same time, basic information of all buildings within the area to be evaluated is obtained by aerial remote sensing mapping, the basic information of each building includes the building height and the horizontal coordinates of a number of contour points on the outer contour line of the building, the horizontal coordinates of the contour points are used to locate the position of each building in the area to be evaluated, and the building plane of the building is surrounded by all the contour points of the building, and then each building plane is subjected to quadrilateral regularization segmentation processing to obtain the initial face domain of each building, each initial face domain corresponds to a height, and the building height of each building is assigned to the height corresponding to the initial face domain of the building;

[0015] Take the vertices of each initial region as data points to draw a heat map of the area to be evaluated, compare the satellite remote sensing image with the heat map, and review the accuracy of the initial region:

[0016] If the positions of the data points on the heat map match the satellite remote sensing image, the initial domain is accurate and the initial domain is used for the next step of processing;

[0017] If the positions of the data points on the heat map do not match the satellite remote sensing image, the initial domain is inaccurate and the aerial remote sensing mapping is used again from step 1 to obtain the next basic building information.

[0018] The quadrilateral regularization segmentation process in step 1 is specifically as follows: firstly, the architectural plane of the building is segmented into a plurality of plane units, then the original plane unit is replaced by the minimum circumscribed rectangle of each plane unit, and the union of each plane unit of the formed new rectangle is used as the initial face area of ​​the building on the architectural plane;

[0019] The plane unit is selected from rectangle, triangle, circle and other regular shapes.

[0020] In step 3, the specific operation of reassigning the height corresponding to each grid unit using the height corresponding to each simulation area is as follows:

[0021] If the simulation domains at different heights do not overlap, the height of each simulation domain is assigned to the height corresponding to the grid unit inside the simulation domain;

[0022] If simulation domains at different heights overlap, the height corresponding to the grid cells in the overlapping area is the maximum height corresponding to the overlapping simulation domains.

[0023] In step 5, the ground roughness category of the area to be evaluated is determined based on the minimum value of the average building height under all wind directions. The specific determination method is:

[0024] When the minimum value of the average building height is between 9m and 18m, the ground roughness category of the area to be assessed is judged to be Class C ground roughness category;

[0025] If the minimum average building height is less than 9m, the ground roughness category of the area to be assessed is judged as Class A ground roughness category or Class B ground roughness category; and when the minimum average building height is less than 9m:

[0026] When the area to be evaluated is a river surface, sea surface, lake surface, or desert, the surface roughness category of the area to be evaluated is determined to be Class A surface roughness category;

[0027] Otherwise, it is judged as Class B ground roughness category.

[0028] The radius of the area to be evaluated is a larger value between 20 times the maximum building height in the area to be evaluated and 2 km.

[0029] The central angle of the wind direction influence area is 180°, 30° or 45°.

[0030] The building is a building, a structure or a mountain.

[0031] The beneficial effects of the present invention are:

[0032] 1. The present invention proposes a new method for quantitatively determining the landform roughness category, which is used to determine the landform conditions on site, such as complex changes in building height and site category, making up for the deficiency of using qualitative methods to describe the landform roughness category in the load specification, which makes it difficult to determine.

[0033] 2. The present invention is suitable for judging the roughness of landforms at sites with uneven building heights and different site types. The method is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of the method.

[0035] Figure 2 It is a building location heat map generated based on the processed data.

[0036] Figure 3 It is a schematic diagram of data regularization.

[0037] Figure 4 This is a schematic diagram of overlapping values ​​of face domains.

[0038] Figure 5 This is a typical schematic diagram of overlapping coverage of the area

[0039] Figure 6 It is the calculated result of the average height of a typical project under the commonly used wind direction angle, and the comparison values ​​are all Class C landforms. DETAILED DESCRIPTION

[0040] In order to more clearly illustrate the technical solution implemented by the present invention, the drawings of the embodiments are briefly introduced below.

[0041] A method for calculating the average building height and determining the landform category using field measured data includes the following steps: Figure 1 As shown:

[0042] Step 1: First, use aerial remote sensing to obtain the basic information of all buildings in the area to be evaluated. Then, obtain the building plan of each building through the basic information of the building. Perform quadrilateral regularization segmentation on the building plan to obtain the initial area of ​​each building, and determine the building height corresponding to each initial area.

[0043] Step 2: Divide the area to be evaluated into grids according to the preset size of the grid units to form a number of grid units, obtain the horizontal coordinates of the center point of the area to be evaluated, subtract the horizontal coordinates of the center point from the horizontal coordinates of the four corner points of the initial surface area, and perform normalization processing so that the corner points are changed from the world coordinate system to the relative coordinate system. After normalization processing, the numerical values ​​of the horizontal coordinates of the corner points are smaller than before processing, which is convenient for subsequent calculations. Each grid unit corresponds to a height, and the height corresponding to each initial surface area is assigned to the height corresponding to the grid unit located inside the initial surface area, and the height corresponding to the grid unit outside the initial surface area is zero;

[0044] Step 3: Based on the height influence principle, the height of the grid unit is modified. The height influence principle is that the building height will affect the judgment of the landform category: the initial domain is extended outward from the initial domain with its own height as the extension distance to form a new domain and use it as the simulation domain. The extension method of the initial domain is as follows: Figure 4 As shown, the height corresponding to each simulated surface area is the height corresponding to the initial surface area before it is extended outward, and then the height corresponding to each grid unit is reassigned using the height corresponding to each simulated surface area;

[0045] Step 4: Take a fan at any position in the area to be evaluated with a preset central angle as the wind direction influence area. The vertex and radius of the wind direction influence area are the center and radius of the area to be evaluated respectively. The wind direction of the wind direction influence area is perpendicular to the tangent line of the arc of the wind direction influence area. Take the average value of the grid unit height in the wind direction influence area as the average building height under the wind direction of the wind direction influence area, such as Figure 6 As shown;

[0046] Step 5: Repeat step 4 multiple times to obtain the average building heights under different wind directions, and determine the ground roughness category of the area to be evaluated based on the minimum value of the average building heights under all wind directions. The ground roughness category is Class A ground roughness category, Class B ground roughness category, Class C ground roughness category, or Class D ground roughness category. The wind load of the building is calculated using different ground roughness categories, thereby realizing the quantitative calculation of the wind load.

[0047] The ground roughness category is determined based on the building density and building height of the area to be evaluated. Class D ground roughness category indicates that the buildings in the area to be evaluated are densely distributed and the building heights are high, while Class A ground roughness category indicates that the buildings in the area to be evaluated are sparsely distributed and the building heights are low.

[0048] Step 1 is as follows: first, use aerial remote sensing mapping to take a satellite remote sensing image of the area to be evaluated. At the same time, aerial remote sensing mapping combined with total station, level, tape measure and other measuring tools to obtain the basic information of all buildings within the area to be evaluated. The basic information of each building includes the building height and the horizontal coordinates of several contour points on the outer contour line of the building. The horizontal coordinates of the contour points are used to locate the position of each building in the area to be evaluated. The building plane of the building is surrounded by all the contour points of the building, and then each building plane is subjected to quadrilateral regularization segmentation to obtain the initial surface area of ​​each building, such as Figure 3 As shown, each initial area corresponds to a height, and the building height of each building is assigned to the height corresponding to the initial area of ​​the building;

[0049] Take the vertices of each initial region as data points to draw a hotspot map of the area to be evaluated, such as Figure 2 As shown in the figure, the heat map consists of several data points with known horizontal coordinates. The satellite remote sensing image and the heat map are compared to review the accuracy of each data point in the heat map and the accuracy of the initial surface area to ensure the availability of the data points after quadrilateral regularization:

[0050] If the positions of the data points on the heat map match the satellite remote sensing image, the initial domain is accurate and the initial domain is used for the next step of processing;

[0051] If the location of each data point on the heat map does not match the satellite remote sensing map, the initial domain is inaccurate, and the next building basic information acquisition is carried out by reusing the aerial remote sensing mapping from step 1;

[0052] The quadrilateral regularization segmentation process in step 1 is specifically as follows: first, the building plane of the building is segmented into a number of plane units, and then the original plane unit is replaced by the minimum circumscribed rectangle of each plane unit, and the union of each plane unit of the formed new rectangle is used as the initial surface area of ​​the building on the building plane;

[0053] The planar elements are selected from rectangles, triangles, circles and other regular shapes.

[0054] The quadrilateral regularization segmentation process divides the building into several regular rectangles on the building plane, and appropriately increases or decreases the contour points on the original building plane outer contour line to facilitate subsequent programmatic reading and use. Compared with the actual building plane, the difference between the building plane area after the quadrilateral regularization segmentation process and the actual building area is no more than one-fourth of the actual building area, so as to reduce the impact of the quadrilateral regularization segmentation process on the building area size.

[0055] In step 3, the specific operation of reassigning the height corresponding to each grid unit using the height corresponding to each simulation area is as follows:

[0056] If the simulation domains at different heights do not overlap, the height of each simulation domain is assigned to the height corresponding to the grid unit inside the simulation domain;

[0057] If simulation domains at different heights overlap, the height of the grid cells in the overlapping area is the maximum height of the overlapping simulation domains. Figure 5 As shown;

[0058] In step 5, the ground roughness category of the area to be evaluated is determined based on the minimum value of the average building height under all wind directions. The specific determination method is:

[0059] When the minimum value of the average building height is between 9m and 18m, the ground roughness category of the area to be assessed is judged to be Class C ground roughness category;

[0060] If the minimum average building height is less than 9m, the ground roughness category of the area to be assessed is judged as Class A ground roughness category or Class B ground roughness category; and when the minimum average building height is less than 9m:

[0061] When the area to be evaluated is a river, sea, lake, desert or other landforms, the surface roughness category of the area to be evaluated is determined to be Class A surface roughness category;

[0062] Otherwise, it is judged as Class B ground roughness category, such as Figure 6 shown.

[0063] The radius of the area to be assessed is the larger value between 20 times the maximum building height in the area to be assessed and 2 km.

[0064] The central angle of the wind direction impact area is 180°, 30° or 45°, etc.

[0065] A building is a structure, a building or a mountain. This method can be used to calculate the average height of buildings, structures and mountains within the area to be evaluated.

[0066] The preset grid unit size is 5m*5m. The smaller the grid unit size, the more accurate the average building height obtained. Therefore, the grid unit size should not exceed 10m*10m.

[0067] The above specific implementation modes are used to illustrate the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for calculating the average building height and determining the landform type using field measured data, characterized in that: The following steps are involved: Step 1: First, use aerial remote sensing to obtain the basic information of all buildings in the area to be evaluated. Then, obtain the building plan of each building through the basic information of the building. Perform quadrilateral regularization segmentation on the building plan to obtain the initial area of ​​each building, and determine the building height corresponding to each initial area. Step 2: Divide the area to be evaluated into grids according to the preset grid unit size to form a number of grid units, each grid unit corresponds to a height, and assign the height corresponding to each initial surface area to the height corresponding to the grid unit inside the initial surface area, and the height corresponding to the grid unit outside the initial surface area is zero; Step 3: Correct the height of the grid unit: extend the initial domain outward on the initial domain with its own height as the extension distance to form a new domain as the simulation domain. The height corresponding to each simulation domain is the height corresponding to the initial domain before the extension. Then, use the height corresponding to each simulation domain to reassign the height corresponding to each grid unit. Step 4: Take a fan-shaped area at any position in the area to be evaluated with a preset central angle as the wind direction influence area, the vertex and radius of the wind direction influence area are respectively the center and radius of the area to be evaluated, the wind direction of the wind direction influence area is perpendicular to the tangent line of the arc of the wind direction influence area, and take the average value of the grid unit height in the wind direction influence area as the average building height under the wind direction corresponding to the wind direction of the wind direction influence area; Step 5: Repeat step 4 multiple times to obtain the average building heights under different wind directions, and determine the ground roughness category of the area to be evaluated based on the minimum value of the average building heights under all wind directions. The ground roughness category is Class A ground roughness category, Class B ground roughness category, Class C ground roughness category, or Class D ground roughness category. The wind load of the building is calculated using different ground roughness categories, thereby realizing the quantitative calculation of the wind load. The ground roughness category is determined based on the building density and building height of the area to be evaluated. Class D ground roughness category indicates that the buildings in the area to be evaluated are densely distributed and the building heights are high, while Class A ground roughness category indicates that the buildings in the area to be evaluated are sparsely distributed and the building heights are low.

2. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: The step 1 is specifically as follows: first, a satellite remote sensing image of the area to be evaluated is taken by aerial remote sensing mapping, and at the same time, basic information of all buildings within the area to be evaluated is obtained by aerial remote sensing mapping, the basic information of each building includes the building height and the horizontal coordinates of a number of contour points on the outer contour line of the building, the horizontal coordinates of the contour points are used to locate the position of each building in the area to be evaluated, and the building plane of the building is surrounded by all the contour points of the building, and then each building plane is subjected to quadrilateral regularization segmentation processing to obtain the initial face domain of each building, each initial face domain corresponds to a height, and the building height of each building is assigned to the height corresponding to the initial face domain of the building; Take the vertices of each initial region as data points to draw a heat map of the area to be evaluated, compare the satellite remote sensing image with the heat map, and review the accuracy of the initial region: If the positions of the data points on the heat map match the satellite remote sensing image, the initial domain is accurate and the initial domain is used for the next step of processing; If the positions of the data points on the heat map do not match the satellite remote sensing image, the initial domain is inaccurate and the aerial remote sensing mapping is used again from step 1 to obtain the next basic building information.

3. The method for calculating the average building height and determining the landform type using field measured data according to claim 2, characterized in that: The quadrilateral regularization segmentation process in step 1 is specifically as follows: firstly, the architectural plane of the building is segmented into a plurality of plane units, then the original plane unit is replaced by the minimum circumscribed rectangle of each plane unit, and the union of each plane unit of the formed new rectangle is used as the initial face area of ​​the building on the architectural plane; The plane unit is selected from a rectangle, a triangle, and a circle.

4. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: In step 3, the specific operation of reassigning the height corresponding to each grid unit using the height corresponding to each simulation area is as follows: If the simulation domains at different heights do not overlap, the height of each simulation domain is assigned to the height corresponding to the grid unit inside the simulation domain; If simulation domains at different heights overlap, the height corresponding to the grid cells in the overlapping area is the maximum height corresponding to the overlapping simulation domains.

5. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: In step 5, the ground roughness category of the area to be evaluated is determined based on the minimum value of the average building height under all wind directions. The specific determination method is: When the minimum value of the average building height is 9m~18m, the ground roughness category of the area to be evaluated is judged as Class C ground roughness category; If the minimum average building height is less than 9m, the ground roughness category of the area to be assessed is judged as Class A ground roughness category or Class B ground roughness category; and when the minimum average building height is less than 9m: When the area to be evaluated is a river surface, sea surface, lake surface, or desert, the surface roughness category of the area to be evaluated is determined to be Class A surface roughness category; Otherwise, it is judged as Class B ground roughness category.

6. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: The radius of the area to be evaluated is a larger value between 20 times the maximum building height in the area to be evaluated and 2 km.

7. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: The central angle of the wind direction influence area is 180°, 30° or 45°.

8. The method for calculating average building height and determining landform type using field measured data according to claim 1, characterized in that: The building is a building, a structure or a mountain.

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