Method for calculating tree height and determining planting point using a map

Abstract

The application discloses a method for calculating tree height and determining planting point by using a map, comprising the following steps: selecting two satellite images of the same place taken at different times in a map, and determining tangent values of their deformation azimuths; obtaining coordinates of the same point on the crown of the same tree in the two satellite images; obtaining a cosine value of the shooting angle of one of the satellite images; determining real coordinates of the point before deformation; establishing an equation group according to the relationship between deformation and tree height, and solving tree height and base point coordinates of the tree, which represent planting point coordinates. The method can obtain tree height and planting point without field measurement, is simple to operate, short in time consumption, and can be applied to sampling detection of different urban trees.

Description

Technical Field

[0001] This invention relates to the field of remote sensing, and more particularly to a method for calculating tree height and determining planting points using maps. Background Technology

[0002] Urban trees are an important component of the urban ecosystem, playing an indispensable and positive role in the environment, such as increasing air humidity, improving ventilation, and regulating microclimates. However, with the rapid advancement of urbanization, urban construction has had a significant impact on urban trees, making their safety and health increasingly a concern. As a vital part of the urban ecological environment, the safety of urban trees cannot be ignored. Tree height and the position of the trunk are important indicators for risk assessment in terms of safety.

[0003] Currently, the primary method for obtaining tree height is on-site measurement, which is not only time-consuming but also extremely demanding on the surveyors. While methods such as map street view and drone-based lidar point cloud have proven feasible to some extent, they still present significant operational challenges, especially remote sensing technology, which has been widely used in forestry in recent years. Summary of the Invention

[0004] In view of the aforementioned shortcomings of the prior art, the technical problem to be solved by the present invention is that current methods for obtaining tree height are time-consuming and labor-intensive, and the use of methods such as map street view, UAV lidar point cloud, etc., is difficult. The present invention provides a method for calculating tree height and determining planting points using maps, which can obtain tree height and planting points without on-site measurement. It is simple to operate, quick, and can be applied to the sampling and detection of trees in different cities.

[0005] To achieve the above objectives, the present invention provides a method for calculating tree height and determining planting points using a map, comprising the following steps:

[0006] Select two satellite images of the same location taken at different times on the map and determine the tangent of its azimuth angle.

[0007] Obtain the coordinates of the same location on the canopy of the same tree in two satellite images;

[0008] Obtain the cosine value of the shooting angle of one of the satellite images;

[0009] Determine the true coordinates of the site before deformation;

[0010] Based on the relationship between deformation and tree height, a system of equations is established to solve for the tree height and the coordinates of the base point of the tree. The coordinates of the base point represent the coordinates of the planting point.

[0011] Furthermore, by selecting two satellite images taken at different times for the same location on the map, the tangent value of its deformed azimuth angle is determined, specifically including:

[0012] Select two satellite images taken at different times for the same location on the map, and label them T1 and T2 respectively. Then, use the map's built-in ruler function for any deformed building or structure that can be observed with the naked eye, taking the base point as the first point and the deformed point as the second point, to obtain the deformation azimuth angle. Then, calculate the tangent value of the deformation azimuth angle based on the deformation azimuth angle.

[0013] Furthermore, to obtain the coordinates of the same point on the canopy of the same tree in two satellite images, specifically, to find a clearly identifiable point on the canopy of the same tree in the two satellite images and move the mouse close to it to obtain the coordinates.

[0014] Further, the cosine value of the shooting angle of one of the satellite images is obtained, specifically including the following steps:

[0015] Measure and record relevant data of deformed buildings and structures visible to the naked eye in one of the satellite images T1, including shadow azimuth, deformation amount, shadow length, and shooting date;

[0016] Enter the shooting date in the Planit software, adjust the solar altitude angle to obtain the same shadow azimuth angle, and record the solar altitude angle at this time;

[0017] The height of the selected building is calculated using the formula, and then the tangent of the shooting angle is calculated.

[0018] Furthermore, for the calculation of coordinates in a certain area, only the value in seconds is recorded, while the values ​​in degrees and minutes are omitted.

[0019] Furthermore, when the deformation of a building or structure appears as rotation when viewed from the elevation, it means that the length of the deformed object has not changed. The ratio of the height of the building or structure to the amount of deformation, obtained by calculating the solar altitude angle at the time of shooting using Planit software, is the cosine value of the shooting angle.

[0020] Furthermore, the calculation method for determining the true coordinates of the site before deformation is as follows: Tangent of the deformed azimuth angle = Longitude after deformation - True longitude / Latitude after deformation - True latitude.

[0021] Furthermore, the tree height is determined to be calculated as: tree height = deformation amount * tangent of shooting angle. The deformation amount obtained through coordinate difference needs to be converted into data in meters before calculation.

[0022] Furthermore, the method for obtaining the tangent value of the deformed azimuth angle is as follows: when the azimuth angle is between 0 and 90 degrees, calculate by subtracting the azimuth angle from 90; when the azimuth angle is between 90 and 180 degrees, calculate by subtracting 90 degrees; when the azimuth angle is between 180 and 270 degrees, calculate by subtracting the azimuth angle from 270; and when the azimuth angle is between 270 and 360 degrees, calculate by subtracting 270 degrees.

[0023] Furthermore, the base point of the tree is determined as the distance between the deformed base point and the real base point = the distance between the deformed crown point and the real crown point. Here, the base point refers to the point that coincides with the planting point in the planar projection, is on the same vertical line as the planting point in the elevation, and is on the same horizontal plane as the crown mark point.

[0024] Technical effect

[0025] This invention provides a method for calculating tree height and determining planting points using maps. This method is based on existing satellite imagery resources and utilizes two-dimensional planar images to obtain three-dimensional data. Furthermore, the method is easy to operate.

[0026] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating a preferred embodiment of the present invention of a method for calculating tree height and determining planting points using a map;

[0028] Figure 2 This is an example of a preferred embodiment of the present invention, showing the location of an object photographed on May 7, 2019 (date 1).

[0029] Figure 3 This is an example of a preferred embodiment of the present invention, showing the location of a method for calculating tree height and determining planting points using a map, photographed on the second date (December 9, 2019).

[0030] Figure 4 This is an example of a preferred embodiment of the present invention, showing a method for calculating tree height and determining planting points using a map, with the location of the subject taken on May 7, 2019.

[0031] Figure 5 This is an example of a preferred embodiment of the present invention, showing a method for calculating tree height and determining planting points using a map, with the location map taken on the second shooting date (December 9, 2019).

[0032] Figure 6This is a tilted and distorted photographic view of a preferred embodiment of the present invention, illustrating a method for calculating tree height and determining planting points using a map. Detailed Implementation

[0033] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0034] In the following description, specific details, such as particular internal procedures and techniques, are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will appreciate that the invention may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of the invention with unnecessary detail.

[0035] like Figure 1 As shown, this embodiment of the invention provides a method for calculating tree height and determining planting points using a map, including the following steps:

[0036] S1. Select two satellite images taken at different times for the same location on the map and determine the tangent value of its deformed azimuth angle;

[0037] S2. Obtain the coordinates of the same location on the canopy of the same tree in two satellite images;

[0038] S3. Obtain the cosine value of the shooting angle of one of the satellite images;

[0039] S4. Determine the true coordinates of the site before deformation;

[0040] S5. Establish a system of equations based on the relationship between deformation and tree height, and solve for the tree height and the coordinates of the base point of the tree. The coordinates of the base point represent the coordinates of the planting point.

[0041] Specifically, S1 involves selecting two satellite images of the same location taken at different times on the map and determining the tangent value of its deformed azimuth angle, including:

[0042] S11. Select two satellite images taken at different times for the same location on the map, denoted as T1 and T2 respectively. Then, use the map's built-in ruler function for any observable deformed building or structure. Taking a cube-shaped building as an example, before deformation, the base and top corners of the cube are on the same vertical line. After deformation, the two corners are offset and do not coincide on the plan view. Therefore, take the location of the base corner as the first point and the location of the deformed top corner as the second point, obtain the deformation azimuth angle, and then denot them as α1 and α2 respectively according to the deformation azimuth angle α; (wherein, the location of the base corner is considered as the base point, and the location of the top corner is the deformed point of the base point.)

[0043] S12, calculate the tangent of the deformed azimuth angle, denoted as e for T1 and f for T2. When α is between 0 and 90 degrees, e(f) = tan(90 - α); when α is between 90 and 180 degrees, e(f) = tan(α - 90); when α is between 180 and 270 degrees, e(f) = tan(270 - α); when α is between 270 and 360 degrees, e(f) = tan(α - 270). The method for obtaining the tangent of the deformed azimuth angle is as follows: when the azimuth angle is between 0 and 90 degrees, subtract the azimuth angle from 90; when the azimuth angle is between 90 and 180 degrees, subtract 90 degrees; when the azimuth angle is between 180 and 270 degrees, subtract the azimuth angle from 270; and when the azimuth angle is between 270 and 360 degrees, subtract 270 degrees.

[0044] S2. Obtain the coordinates of the same point on the canopy of the same tree in two satellite images, T1 and T2. Specifically, find clearly identifiable points on the canopy of the same tree in both satellite images, such as points near missing canopies or new shoots, and move the mouse close to them to obtain the coordinates. Points on T1 are recorded as (a, b) (a is latitude, b is longitude), and points on T2 are recorded as (c, d) (c is latitude, d is longitude). For a, b, c, and d, usually only the second values ​​for latitude and longitude are written; the degree and minute values ​​are omitted.

[0045] S3. Obtain the cosine value of the shooting angle of one of the satellite images, specifically including the following steps:

[0046] S31. Measure and record relevant data of deformed buildings and structures visible to the naked eye in one of the satellite images T1, including shadow azimuth, deformation (D), shadow length (L), and date of shooting.

[0047] S32. Enter the shooting date in Planit software, adjust the solar altitude angle to obtain the same shadow azimuth angle, and record the solar altitude angle (s) at this time;

[0048] S33. Calculate the height of the selected building using the formula, and then calculate the tangent of the shooting angle. Specifically, this is done using the formula... = H0 / L gives the height of the selected building, H0; then according to the formula... = D / H0 gives the tangent of the shooting angle. .

[0049] It should be noted that when the deformation of a building or structure appears as rotation when viewed from the elevation, it means that the length of the deformed object has not changed. The ratio of the height of the building or structure to the amount of deformation, obtained by calculating the solar altitude angle at the time of shooting using Planit software, is the cosine value of the shooting angle.

[0050] S4. Determine the true coordinates of the sampling points in both images, which belong to the same point on the real tree canopy, i.e., determine the true coordinates of the site before deformation; specifically:

[0051] S41. Assume the coordinates of the marked position on the tree crown before deformation are (m, n).

[0052] S42. Solve the system of equations:

[0053] The calculation method for determining the true coordinates of a location before deformation is as follows: Tangent of the deformed azimuth angle = Longitude after deformation - True longitude / Latitude after deformation - True latitude.

[0054] S5. Establish a system of equations based on the relationship between deformation and tree height, and solve for the tree height and the coordinates of the tree's base points. Specifically, this includes:

[0055] S51. Input the converted coordinates (a, b) and (m, n) into the program, and output the actual distance T (in meters).

[0056] S52, Calculate tree height (H): H= ;

[0057] S53. Obtain the coordinates of the base points after deformation. Represent the coordinates of the base point (x0, y0) that is on the same vertical line as the planting point and on the same horizontal plane as the tree crown marker. The coordinates after deformation T1 are represented as (x1, y1), and the coordinates after deformation T2 are represented as (x2, y2), where the former is latitude and the latter is longitude. Points (x1, y1) and (a, b) or (c, d) and (x0, y0) form a right triangle. Using the Pythagorean theorem, calculate the distance between points (x1, y1) and (x0, y0). Since the distance between points (x1, y1) and (x0, y0) is equal to the distance between points (a, b) and (c, d), a system of equations can be established to solve for the coordinates of the base points.

[0058] S54. Solve the system of equations:

[0059]

[0060] Since the calculation is quite complex, it can be performed by inputting the corresponding formulas in MATLAB software.

[0061] The tree height is calculated as: tree height = deformation amount * tangent of shooting angle. The deformation amount obtained through coordinate difference needs to be converted into data in meters before calculation.

[0062] The base point of a tree is determined by the distance between the deformed base point and the real base point, which is equal to the distance between the deformed crown point and the real crown point. The base point refers to the coordinates of the point whose planar projection coincides with the planting point, is on the same vertical line as the planting point on the elevation, and is on the same horizontal plane as the crown mark point.

[0063] The following experiment will use 30 camphor trees on the campus of Shanghai Normal University (Fengxian Campus) as an example to verify the method by comparing the tree height calculated by this invention with the actual measured data. Figure 2-6 As shown, the details are as follows:

[0064] S1. Select two satellite images taken at different times for the location of 30 camphor trees on the map, and determine the tangent value of their deformed azimuth angle;

[0065] S2. Obtain the coordinates of the same point on the canopy of the same tree in both images;

[0066] S3. Obtain the cosine value of the shooting angle of one of the images;

[0067] S4. Determine the true coordinates of the site before deformation;

[0068] S5. Establish a system of equations based on the relationship between deformation and tree height, and solve for the tree height and the coordinates of the tree's base point. The base point coordinates represent the coordinates of the planting point.

[0069] In this embodiment, step S1 specifically includes:

[0070] S11. Select two historical images T1 (taken on May 7, 2019) and T2 (taken on December 9, 2019). Use the map's built-in scale function on any building or structure that can be deformed by the naked eye. Take the base point as the first point and the deformed point as the second point, and obtain its deformation azimuth angle α. Record it as α1 and α2, where α1 = 340° and α2 = 276°.

[0071] S12. Obtain the tangent value of the deformed azimuth angle, denoted as e for T1 and f for T2. Where e = tanα1 = 2.75 and f = tanα2 = 0.11.

[0072] Step S2 is as follows:

[0073] like Figure 4-5 As shown, obtain the coordinates of the same point on the canopy of the same tree in two graphs. Taking tree 1 as an example, the point on T1 is recorded as (20.46, 44.42), and the point on T2 is recorded as (20.37, 44.47). a, b, c, and d are usually recorded only in seconds for latitude and longitude. The coordinates of the remaining 29 trees are recorded sequentially.

[0074] Step S3 is as follows:

[0075] S31. Record and measure the deformation azimuth angle (163°), deformation amount (D) 5.44, shadow length (L) 23.91, and shooting date (December 9, 2019) of the buildings or structures in T1 that are visible to the naked eye.

[0076] S32. Enter the shooting date in Planit software, adjust the solar altitude angle to obtain the same shadow azimuth angle, and record the solar altitude angle (s) at this time, s = 34.5°;

[0077] S33, According to the formula = H0 / L gives the height of the selected building, i.e., H0 = 16.43;

[0078] S34, According to the formula = D / H0 gives the tangent of the shooting angle. .

[0079] Step S4 specifically involves:

[0080] S41. Assume the coordinates of the marked position on the tree crown before deformation are (m, n).

[0081] S42. Solve the system of equations: The coordinates of the marker point are (20.4825, 44.4816), which can be simplified to (20.48, 44.48).

[0082] Step S5 is as follows:

[0083] S51. Input the converted coordinates (20.37, 44.47) and (20.48, 44.48) into the program. For example, the complete form of (20.37, 44.47) is (30°50′20.37″, 121°30′44.47″), which is converted to coordinates in degrees: (30.831991, 121.512353). Output the actual distance T = 3.573546 m;

[0084] S52. Calculate the tree height (H). According to the formula H = The tree height was found to be 10.79 m.

[0085] S53, such as Figure 6 As shown, the coordinates of the base point, which is on the same vertical line as the planting point and on the same horizontal plane as the tree crown marker, are represented as (x0, y0). The coordinates of T1 after transformation are represented as (x1, y1), and the coordinates of T2 after transformation are represented as (x2, y2). The former represents latitude, and the latter represents longitude. Taking T1 as an example, points (x1, y1), (a, b) or (c, d), and (x0, y0) form a right triangle. Using the Pythagorean theorem, the distance between points (x1, y1) and (x0, y0) can be calculated. Since the distance between points (x1, y1) and (x0, y0) is equal to the distance between points (a, b) and (c, d), a system of equations can be established to solve for the coordinates of the base point.

[0086] S53. Solve the system of equations:

[0087]

[0088] The experimental calculation results are shown in Table 1.

[0089] Table 1. Accuracy Verification Table of Calculation Method

[0090]

[0091] As can be seen from the above embodiments, the present invention is feasible and can obtain the tree height using two-dimensional planar images in a map, with advantages such as low cost and easy operation. Table 1 shows that the accuracy of this method can reach approximately 95%, and the main factors affecting its accuracy are the clarity of the pixel image and human error.

[0092] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for calculating tree height and determining planting points using a map, characterized in that, Includes the following steps: Select two satellite images taken at different times (T1 and T2) for the same location on the map, and determine the tangent of its azimuth angle; specifically including: Two satellite images taken at different times for the same location are selected on the map and labeled T1 and T2, respectively. Then, the map's built-in scale function is used for any deformed building or structure that can be observed by the naked eye. The location of the bottom corner is taken as the first point, and the location of the deformed top corner is taken as the second point. The deformed azimuth angle α is obtained and labeled α1 and α2, respectively. The location of the bottom corner is considered as the base point, and the location of the top corner is the deformed point of the base point. The tangent value of the deformed azimuth angle is calculated. The method for obtaining the tangent value of the deformed azimuth angle is as follows: when the azimuth angle is between 0 and 90 degrees, it is calculated by subtracting the azimuth angle from 90; when the azimuth angle is between 90 and 180 degrees, it is calculated by subtracting 90 degrees; when the azimuth angle is between 180 and 270 degrees, it is calculated by subtracting the azimuth angle from 270; when the azimuth angle is between 270 and 360 degrees, it is calculated by subtracting 270 degrees. Obtain the coordinates of the same location on the canopy of the same tree in two satellite images T1 and T2, denoted as (a, b) and (c, d); Obtain the cosine value of the shooting angle of one of the satellite images; specifically, this includes measuring and recording relevant data of deformed buildings or structures visible to the naked eye in one of the satellite images T1, including shadow azimuth, deformation D, shadow length L, and shooting date; and recording the solar altitude angle s in Planit software according to the formula. = H0 / L gives the height of the selected building, H0; then according to the formula... = D / H0 gives the cosine of the shooting angle. ; Determine the true coordinates of the site before deformation; assume the coordinates of the marked site on the tree canopy before deformation are (m, n); solve the system of equations: , The calculation method for determining the true coordinates of a location before deformation is: Tangent of the deformed azimuth angle = Longitude after deformation - True longitude / Latitude after deformation - True latitude; A system of equations is established based on the relationship between deformation and tree height to solve for the tree height and the coordinates of the tree's base points. Specifically, this includes: Input the converted coordinates (a, b) and (m, n), output the actual distance T in meters; calculate the tree height (H): H = By solving the system of equations: ， Obtain the coordinates of the base point after deformation; The coordinates of the base point, which is on the same vertical line as the planting point and on the same horizontal plane as the tree crown marker, are represented as (x0, y0).

2. The method for calculating tree height and determining planting points using a map as described in claim 1, characterized in that, To obtain the coordinates of the same point on the canopy of the same tree in two satellite images, specifically, find a clearly identifiable point on the canopy of the same tree in both satellite images and move the mouse close to it to obtain the coordinates.

3. The method for calculating tree height and determining planting points using a map as described in claim 2, characterized in that, For calculations of coordinates in a specific area, only the values ​​in seconds are recorded; the values ​​in degrees and minutes are omitted.

4. The method for calculating tree height and determining planting points using a map as described in claim 2, characterized in that, When the deformation of a building or structure appears as rotation when viewed from the elevation, it means that the length of the deformed object has not changed. The ratio of the height of the building or structure to the amount of deformation is obtained by calculating the solar altitude angle at the time of shooting using Planit software, and is then the cosine value of the shooting angle.

5. The method for calculating tree height and determining planting points using a map as described in claim 1, characterized in that, The base point of a tree is determined by the distance between the deformed base point and the actual base point, which is equal to the distance between the deformed crown point and the actual crown point. The base point refers to the point whose planar projection coincides with the planting point, is on the same vertical line as the planting point on the elevation, and is on the same horizontal plane as the crown marker point.

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