CN110222586A - A kind of calculating of depth of building and the method for building up of urban morphology parameter database - Google Patents

Abstract

A method for calculating the height of a building and establishing a database of urban form parameters is disclosed. The method includes the following steps: Step 1: Use spectral features to classify remote sensing images of buildings and extract shadow information, and use shadow vector graphics to segment the straight line in the direction of the sun's projection to calculate the length of the building's shadow: Step 2: According to the shadow Calculate the height of the building from the length; and step 3: perform image smoothing processing on the remote sensing image of the building, perform edge detection and edge connection on the processed image, and remove shadows and vegetation, and then use area recognition to extract the building target, and the image Vectorization is performed to obtain the outline plan of the building; the method of extracting the height and outline of the building by processing a single satellite remote sensing image has the advantages of simple operation, fast and efficient, and relatively high extraction accuracy.

Description

A method for calculating the height of buildings and establishing a database of urban morphological parameters

technical field

The invention relates to the technical field of building height calculation, in particular to a building height calculation method and a method for establishing a city form parameter database.

Background technique

With the rapid development of remote sensing technology, high-resolution remote sensing images can identify smaller objects, and the organizational structure of objects can be more clearly reflected. For important parts of a city such as buildings, roads, water bodies and green spaces, people can more easily observe their structures through remote sensing images, providing data sources for the development of 3D mapping, urban planning and other fields. At present, the extraction of remote sensing images of green spaces and water bodies is relatively mature, while buildings and roads are difficult to extract due to the complexity of their structures. Construct the corresponding three-dimensional digital map of the building.

In addition, in the fields of weather monitoring and environmental monitoring, building information is also very important. Different from the natural vegetation in nature, a new type of canopy, the urban canopy, will be formed in the city due to changes in roads, buildings and human activities. In the urban canopy, high-rise buildings and higher building density increase the surface roughness, and the albedo of road surfaces, building walls and roofs is quite different from the natural vegetation canopy, all of which affect the urban meteorology. Variety. The change of the urban canopy on the wind speed and the urban heat island effect will have an impact on the diffusion of air pollutants, thereby changing the air quality in the city. In the field of meteorological monitoring, commonly used urban-scale meteorological models require high-resolution urban morphological parameters as input data, such as building height, building area, and so on. At present, National Geographic has established a NUDAPT (National Urban Data and Access Portal Tool) urban morphological parameter database describing 44 cities including Houston. The database is established as a city-scale WRF model and other urban meteorological models, air quality models and climate models The model system provides high-resolution gridded urban form parameters as input data. There are few domestic researches related to the urban morphological parameter database, and there is no urban morphological parameter database that can be applied to the urban meteorological model of Chinese cities. Therefore, it is necessary to invent a method for calculating the height of buildings and establishing a database of urban form parameters to solve the above problems.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a method for calculating the height of a building and establishing a database of urban morphological parameters, so as to solve the problems raised in the above-mentioned background art.

According to one aspect of the present invention, there is provided a method for calculating the height of a building and establishing a database of urban morphological parameters, characterized in that it includes the following steps:

Step 1: Use spectral features to classify remote sensing images of buildings and extract shadow information, and use shadow vector graphics to segment the straight line in the direction of the sun's projection to calculate the shadow length of buildings:

Step 2: Calculate the building height based on the shadow length; and

Step 3: Perform image smoothing on the remote sensing images of buildings, perform edge detection and edge connection on the processed images, and remove shadows and vegetation, then use area recognition to extract building targets, and vectorize the image to obtain buildings. outline plan;

The third step further includes matching the building outline plan with the extracted building height data to obtain a high-resolution three-dimensional building map of the city.

According to an embodiment, the method for calculating the building height and establishing the urban form parameter database further includes establishing the urban form parameter database for the building heights calculated in the first step, the second step and the third step.

According to an embodiment, the step 1 further includes performing image enhancement processing on the remote sensing image of the building, and classifying the remote sensing image of the building after the image enhancement processing, wherein the image enhancement processing includes using an enhanced true color fusion method to perform image enhancement processing. Fusion, perform natural color changes on the fused image, and perform linear stretching, color balance, saturation, and contrast adjustments.

According to one embodiment, calculating the building height based on the shadow length includes:

When the sun and the satellite are on the same side of the building, the building height is:

And when the sun and satellites are on either side of the building, the building height is:

H=L ₂ *tanβ;

Among them: L ₂ is the shadow height visible in the remote sensing image of the building;

α is the altitude angle of the satellite;

β is the altitude angle of the sun.

According to one embodiment, performing image smoothing processing on the remote sensing image of the building includes performing histogram equalization and filtering processing on the remote sensing image of the building.

According to an embodiment, the method for calculating the height of a building and establishing a database of urban morphological parameters further includes: using feature measurement and area segmentation to perform post-processing on the extracted building target.

According to one embodiment, the establishment of the urban form parameter database includes: based on the three-dimensional building map, establishing a grid with a resolution of 1km*1km to calculate the urban form parameter.

According to one embodiment, the urban form parameter includes the average building height in each grid, and the calculation formula of the average building height is as follows:

in:

hi is the building height of the i-th building;

N is the number of all buildings in the grid area.

According to one embodiment, the urban form parameter includes the area-weighted average building height in each grid, and the formula for calculating the area-weighted average building height is as follows:

in:

Ai is the floor area of the ith building.

According to an embodiment, the urban form parameter includes the standard deviation of building heights in each grid, and the formula for calculating the standard deviation of building heights is as follows:

in:

H is the average building height.

According to one embodiment, the urban form parameter includes the building plane area fraction in each grid, and the calculation formula of the building plane area fraction is as follows:

in:

A _p is the plane area of all buildings in the grid area;

A _T is the total area of the grid area.

According to one embodiment, the urban form parameter includes the ratio of the building surface area to the planned area in each grid, and the formula for calculating the ratio of the building surface area to the planned area is as follows:

in:

A _R is the roof area of all buildings in the grid area;

A _W is the non-horizontal surface area of all buildings in the grid area.

According to an embodiment, the urban form parameter includes a building height distribution histogram in each grid, and the calculation method of the building height distribution histogram is as follows:

Starting from 0m on the ground surface, set 15 intervals at intervals of 5m, up to 75m, and then calculate the proportional score of all buildings in each grid area in the 15 intervals, thereby obtaining the building height distribution histogram, among which, greater than A 75m building is calculated as 75m.

Technical effects and advantages of the present invention:

1. The present invention has the advantages of simple operation, quickness and high efficiency, and relatively high extraction accuracy by processing a single satellite remote sensing image and extracting the height and outline of buildings;

2. The present invention can obtain a large number of urban building height data and building outline maps by using different satellite remote sensing images, and then match them to build a three-dimensional urban building map;

The invention establishes grids with a certain resolution based on the city three-dimensional architectural map, calculates the urban morphological parameters in each grid, and establishes a database of urban morphological parameters, which can be applied to other advanced urban meteorological models and air quality models such as WRF. and climate models.

Description of drawings

FIG. 1 is a system frame diagram of the present invention.

FIG. 2 is a diagram of a case of extracting building shadows by a supervised classification method in step 1 of the present invention.

FIG. 3 is a case diagram of post-processing of building shadow extraction in step 1 of the present invention.

FIG. 4 is a scene diagram of the sun and the satellite being located on the same side of the building in step 2 of the present invention.

FIG. 5 is a scene diagram showing that the sun and satellites are located on both sides of the building in step 2 of the present invention.

FIG. 6 is a case diagram of the vectorized extraction of building outline information in step 3 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

First, referring to FIG. 1 , it shows a block diagram of a method for calculating the height of a building and establishing a database of urban form parameters according to the present invention. The invention preprocesses high-resolution satellite remote sensing images, adopts spectral feature classification method to extract building shadows, eliminates the influence of interference factors such as small image spots, and calculates building shadow lengths; Calculate the height of the building with the satellite altitude angle; then perform edge detection, edge connection, shadow and vegetation removal, area identification, image vectorization and other operations on the satellite remote sensing image to obtain the building outline plan; The height data is matched to establish a three-dimensional building map; and based on the above three building maps, a grid with a resolution of 1km*1km is established, and the average building height, area-weighted average building height, and building height standard deviation in each grid are calculated. , building plane area fraction, building surface area to planning area ratio, building height distribution histogram and other urban morphological parameters, and finally establish an urban morphological parameter database by calculating urban morphological parameters.

Its specific establishment method steps are as follows:

Step 1: Extract building shadows in satellite remote sensing images:

Perform image enhancement processing on high-resolution satellite remote sensing images, use enhanced true color fusion method for image fusion, and perform natural color changes on the fused images to form natural color images that are basically consistent with ground objects and hues, and perform linear stretching, Color balance, saturation, contrast adjustment.

The processed satellite remote sensing images are classified by spectral feature classification, and the shadow information is extracted by the maximum likelihood classification method of supervised classification. Taking the remote sensing images of the School of Environment of Tsinghua University and surrounding buildings as an example, the above methods are used for processing. The results are shown in Figure 2.

After that, post-processing is performed on the classified images, and the area threshold is set to eliminate scattered and isolated small spots. The result is shown in Figure 3.

Finally, the extracted building shadows are vectorized, and the obtained building shadow vector graphics are used to segment the straight line in the direction of the sun's projection, so as to calculate the building shadow length.

Step 2: Building height extraction: There are two scenarios for calculating the building height through the shadow length:

(1) The sun and the satellite are on the same side of the building:

As shown in Figure 4, the visible shadow part on the satellite remote sensing image will be occluded by the building itself, so the shadow height visible on the satellite remote sensing image as shown in the figure is the shadow generated by the sun shining on the building in real life minus the angle of the satellite. The shadow generated by the building; the above shadow length is related to the height of the building, the altitude angle of the satellite, and the altitude angle of the sun, so the shadow length on the remote sensing image can be measured, and the value of the satellite altitude angle and the sun altitude angle in the remote sensing image can be found. , inversely calculate the height of the building, and its specific calculation formula is as follows:

The shadow heights visible from satellite remote sensing images are:

The building height is:

Where: α is the altitude angle of the satellite;

β is the altitude angle of the sun.

(2) The sun and satellites are located on both sides of the building:

As shown in Figure 5, the shadow part visible on the satellite remote sensing image will not be occluded by the building itself, so the height of the shadow visible on the satellite remote sensing image is consistent with the shadow length produced by the sun irradiating the building in real life; The height of the object is related to the shadow length and the sun height angle, so the shadow length on the remote sensing image can be measured, the value of the sun height angle in the remote sensing image can be found, and the building height can be calculated inversely. The specific calculation formula is as follows:

The shadow heights visible from satellite remote sensing images are:

The building height is:

H=L ₂ *tanβ;

Where: α is the altitude angle of the satellite;

β is the altitude angle of the sun.

Step 3: Vectorized extraction of building outline information:

As shown in Figure 6, taking the remote sensing image of Tsinghua University School of Environment and surrounding buildings as an example, the high-resolution satellite remote sensing image is subjected to histogram equalization and filtering, and the original image is smoothed to remove image noise and individual Isolated points, and set a grayscale limit to filter some interference factors;

Perform edge detection and edge connection on the processed images, and use normalized vegetation index and supervised classification to set appropriate thresholds to remove shadows and vegetation;

Then, the building target is extracted by region recognition, and the extracted target is post-processed by feature measurement and region segmentation, and finally the image vectorization can be used to obtain the building outline plan;

By matching the building outline plan with the extracted building height data, a high-resolution 3D building map of the city can be obtained.

Step 4: Establish the urban form parameter database:

Establish the urban form parameter database for the building heights calculated in steps 1, 2 and 3:

Based on the 3D building map, establish a grid with a resolution of 1km*1km, and calculate the urban form parameters, that is, the urban form parameters include the average building height, area-weighted average building height, standard deviation of building height, and building plane area fraction in each grid. , the ratio of the building surface area to the planned area, the relevant parameters of the building height distribution histogram, and finally establish the urban form parameter database by calculating the urban form parameters, and the calculation method of the urban form parameters is as follows:

The formula for calculating the average building height is as follows:

in:

hi is the building height of the i-th building;

N is the number of all buildings in the grid area;

The formula for calculating the area-weighted average building height is as follows:

in:

Ai is the floor area of the i-th building;

The formula for calculating the standard deviation of the building height is as follows:

in:

H is the average building height;

The formula for calculating the floor area fraction of the building is as follows:

in:

A _p is the plane area of all buildings in the grid area;

A _T is the total area of the grid area;

The formula for calculating the ratio of the building surface area to the planned area is as follows:

in:

A _R is the roof area of all buildings in the grid area;

A _W is the non-horizontal surface area of all buildings in the grid area (such as walls, etc.);

The calculation method of the building height distribution histogram is as follows:

Starting from 0m on the ground surface, set 15 intervals at 5m intervals, up to 75m, and then calculate the proportional score of all buildings in each grid area in the 15 intervals, thereby obtaining the building height distribution histogram;

Among them, buildings larger than 75m are calculated as 75m.

According to another embodiment, the method for calculating the height of a building of the present invention is not only limited to the calculation of buildings, but is also applicable to the calculation of the height of each peak on a mountain range and the calculation of the broken walls of each cliff. Not elaborated one by one.

Finally, it should be noted that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, the The technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be equivalently replaced, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included. within the protection scope of the present invention.

Claims (13)

1. the calculation of a building height and the establishment method of urban form parameter database, it is characterized in that, comprise the following steps: Step 1: Use spectral features to classify remote sensing images of buildings and extract shadow information, and use shadow vector graphics to segment the straight line in the direction of the sun's projection to calculate the shadow length of buildings: Step 2: Calculate the building height based on the shadow length; and Step 3: Perform image smoothing on the remote sensing images of buildings, perform edge detection and edge connection on the processed images, and remove shadows and vegetation, then use area recognition to extract building targets, and vectorize the image to obtain buildings. outline plan; The third step further includes matching the building outline plan with the extracted building height data to obtain a high-resolution three-dimensional building map of the city. 2. the calculation of building height according to claim 1 and the establishment method of urban form parameter database are characterized in that, also comprise: carry out urban form to the calculated building height in step 1, step 2 and step 3 The parameter database is established. 3. the calculation of building height according to claim 1 and the establishment method of urban form parameter database, it is characterized in that, Wherein, the first step further includes performing image enhancement processing on the remote sensing images of buildings, and classifying the remote sensing images of buildings after image enhancement processing, Among them, the image enhancement processing includes using the enhanced true color fusion method to perform image fusion, performing natural color changes on the fused image, and performing linear stretching, color balance, saturation, and contrast adjustment. 4. the calculation of building height according to claim 1 and the establishment method of urban form parameter database, it is characterized in that, calculating building height according to shadow length comprises: When the sun and the satellite are on the same side of the building, the building height is: And when the sun and satellites are on either side of the building, the building height is: H=L ₂ *tanβ; Among them: L ₂ is the shadow height visible in the remote sensing image of the building; α is the altitude angle of the satellite; β is the altitude angle of the sun. 5. the calculation of building height according to claim 1 and the establishment method of urban form parameter database, it is characterized in that, wherein, carrying out image smoothing to building remote sensing image comprises carrying out histogram equalization and building remote sensing image to building remote sensing image. filter processing. 6 . The method for calculating the height of a building and establishing an urban morphological parameter database according to claim 5 , further comprising: post-processing the extracted building objects by using feature measurement and area segmentation. 7 . 7. the calculation of building height according to claim 2 and the establishment method of urban form parameter database, it is characterized in that, the establishment of urban form parameter database comprises: based on three-dimensional building map, establish the grid of 1km*1km resolution, with Calculate urban form parameters. 8. the calculation of building height according to claim 7 and the establishment method of urban form parameter database, it is characterized in that, urban form parameter comprises the average building height in each grid, and described average building height calculation formula is as follows : in: hi is the building height of the i-th building; N is the number of all buildings in the grid area. 9. The calculation of building height according to claim 7 and the method for establishing an urban morphological parameter database, wherein the urban morphological parameter comprises the area-weighted average building height in each grid, and the area-weighted average The formula for calculating the height of the building is as follows: in: Ai is the floor area of the ith building. 10. The method for calculating the height of a building and establishing an urban form parameter database according to claim 7, wherein the urban form parameter comprises the standard deviation of the building height in each grid, and the standard deviation of the building height Calculated as follows: in: H is the average building height. 11. The calculation of building height according to claim 7 and the establishment method of urban form parameter database, it is characterized in that, described urban form parameter comprises the building plane area fraction in each grid, described building plane area fraction Calculated as follows: in: A _p is the plane area of all buildings in the grid area; A _T is the total area of the grid area. 12. The method for calculating the height of a building and establishing an urban form parameter database according to claim 7, wherein the urban form parameter comprises the ratio of the building surface area to the planned area in each grid, and the building The formula for calculating the ratio of surface area to planned area is as follows: in: A _R is the roof area of all buildings in the grid area; A _W is the non-horizontal surface area of all buildings in the grid area. 13. The method for calculating the height of a building and establishing an urban form parameter database according to claim 7, wherein the urban form parameter comprises a building height distribution histogram in each grid, and the building height distribution The histogram is calculated as follows: Starting from 0m on the ground surface, set 15 intervals at intervals of 5m, up to 75m, and then calculate the proportional score of all buildings in each grid area in the 15 intervals, thereby obtaining the building height distribution histogram, among which, greater than A 75m building is calculated as 75m.