How to measure forest stand density

Abstract

The present invention relates to a method for measuring forest stand density, which includes the steps of: (1) determining a measurement area, and taking the flight route passing through the measurement area as the density measurement sampling line; (2) mounting an active distance measurement module on an airplane, starting the active distance measurement module, and the airplane performs flight and measurement according to the flight route, measuring the laser measurement distance at each sampling point, and simultaneously storing the sampling point coordinates of the active distance measurement module; and (3) comparing the sampling point coordinates of the active distance measurement module with the takeoff point coordinates, obtaining the height value of the airplane, calculating the difference between the laser distance measurement distance at each sampling point and the height of the airplane, judging whether the difference is greater than the set threshold, if it is, determining this sampling point as not dense, if it is not, determining this sampling point as dense, summarizing the results of all sampling points, and calculating the forest stand density. The measurement accuracy of the present invention is reliable, the measurement speed is fast, and the measurement process is simple, and the forest stand density measurement work can be completed quickly in large quantities.

Description

[Technical field]

[0001] The present invention relates to the field of measuring machines and instruments, and more particularly to a method for measuring forest stand density. [Background technology]

[0002] Forest stand density is the ratio of the crown projection area to the forest land area in a forest stand, reflecting the extent to which the forest stand utilizes the growth space, and is an important factor in forest resource survey activities. In actual surveys, visual inspection is mainly used, and the actual measurement methods include crown projection, line measurement and statistical methods, which require a large amount of work and slow measurement speed, so in actual work, visual inspection is generally used instead, which is fast but has low measurement accuracy. New methods of new technology are mainly focused on remote sensing image classification, fisheye camera, laser radar and other aspects, and the above methods all have high requirements for measurement operation technology, long processing time at the post-measurement stage, and complex algorithms.

[0003] In view of the above, it is urgently required to provide a method for measuring stand density, which has reliable measurement accuracy, fast measurement speed, simple measurement process, and can quickly complete a large number of stand density measurement tasks. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a method for measuring stand density, which has reliable measurement accuracy, fast measurement speed, simple measurement process, and can quickly complete a large number of stand density measurement tasks.

[0005] The above object is achieved by the following technical solution, which is a method for measuring forest stand density, as follows: (1) determining a measurement area, determining an aircraft flight route, and setting the flight route passing through the measurement area as a congestion measurement sampling line; (2) Equipping the airplane with an active distance measurement module, starting up the active distance measurement module, the airplane performs flight and measurement according to the flight route, and vertically measures the distance from the active distance measurement module to the ground obstacle at multiple sampling points, that is, the distance of the laser distance measurement, and at the same time, the sampling point coordinates of the active distance measurement module storing TIFF2025503764000002.tif5170; (3) acquiring the measurement data of the airplane and solving the forest stand density of the measured area; (3.1) Sampling point coordinates of the active distance measurement module TIFF2025503764000003.tif5170 and takeoff point coordinates Compare TIFF2025503764000004.tif5170 and get the plane height value, defined as follows: TIFF2025503764000005.tif4170 formula, TIFF2025503764000006.tif4170 is the height of the plane, TIFF2025503764000007.tif4170 is the elevation value of the sampling point position, TIFF2025503764000008.tif4170 is the altitude value of the takeoff point position, step, (3.2) calculating the difference between the distance of the laser distance measurement of each sampling point and the height of the aircraft, judging whether the difference is greater than a set threshold, and if so, determining that the sampling point is not blocked, and if not, determining that the sampling point is blocked; (3.3) The steps include: summarizing the results of all sampling points, calculating the number of closed sampling points and the total number of sampling points, and dividing the number of closed sampling points by the total number of sampling points to obtain the forest stand closedness in the measurement area.

[0006] The present invention installs an on-board active distance measurement module on an airplane, and takes the flight route of the airplane to the sample plot or area to be measured as the measurement sampling line, calculates and measures the height from the active distance measurement module of the airplane to the ground obstacle, and judges the forest cover situation of the current sampling point by comparing the difference with the airplane's own height, and finally calculates the forest cover degree by comprehensively stating the numerical values ​​of each sampling point in all the measurement sampling lines. The measurement accuracy of the present invention is reliable, the measurement speed is fast, and the measurement process is simple, and the measurement work of forest cover degree can be completed quickly in large quantities.

[0007] As a further technical solution, in step (3.2) the threshold value is determined based on the measurement objective: if only tree cover is measured, the threshold value is the height of the highest shrub, if both tree cover and shrub cover are measured, the threshold value is the height of the highest ground cover.

[0008] As a further technical solution, the specific steps of the step (2) are as follows: (2.1) recording the measured takeoff point coordinates of the active distance measurement module; (2.2) Starting and flying the aircraft, measuring the current coordinates of the active distance measurement module, comparing the range of the area to be measured, and judging whether it enters the measurement area; (2.3) After entering the measurement area, at a set fixed time interval, vertically measure the distance from the on-board active distance measurement module to the ground obstacle, the measurement point is a sampling point, and at the same time, store the sampling point coordinates of the active distance measurement module.

[0009] As a further technical solution, the calculation formula for the forest cover degree of the measurement area in the step (3) is as follows: TIFF2025503764000009.tif30170

[0010] During the ceremony, TIFF2025503764000010.tif4170 is the forest stand density, TIFF2025503764000011.tif3170 is the number of sampling points to be compressed, TIFF2025503764000012.tif4170 is the total number of sampling points, TIFF2025503764000013.tif4170 is The congestion status of the sampling point of TIFF2025503764000014.tif4170, where 1 indicates congestion and 0 indicates no congestion. TIFF2025503764000015.tif4170 is is the distance of the laser distance measurement of the sampling point of TIFF2025503764000016.tif4170, TIFF2025503764000017.tif4170 is the threshold determined based on the measurement goal.

[0011] As a further technical solution, the PCB circuit board of the active distance measuring module includes a microprocessor, a power supply module, an RTK module, a memory module, a data interface, a timer, a laser distance measuring module and a lamp, wherein the microprocessor is used to complete calculation, storage and control of data measurement, the power supply module is used to provide power for the microprocessor, the RTK module is used to obtain the real-time spatial position coordinates of the active distance measuring module, the memory module is used to store the microprocessor recorded data, the data interface is used for development, testing or field problem handling, the timer is used to provide high-precision timing, and the laser distance measuring module is used to measure the distance to an obstacle.

[0012] In a further technical variant, the aircraft is a drone. Effect of the Invention

[0013] Compared with the prior art, the technical solution of the present invention has the following advantages: High accuracy of density measurement: The present invention measures each sampling line and sampling point, and uses laser distance measurement and altitude comparison methods to ensure the reliability of the measurement results. The sampling points and sampling lines cover the entire sample plot or area being measured, so it can accurately respond to the forest density situation, and can even measure void points in the canopy width of tall trees, with high measurement accuracy.

[0014] The measurement flow is simple and rapid measurement can be realized: the present invention can obtain measurement data by simply flying a drone equipped with an active distance measurement module, without the need for other measurement processes, and the measurement flow is simple. The measurement frequency of each sampling point depends on the emission time interval of the active distance measurement module, so the single measurement time interval of the laser distance measurement module is extremely short (can reach the millisecond level), and rapid measurement can be realized. [Brief description of the drawings]

[0015] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and the description thereof are used to explain the present invention without construing an undue limitation thereon. [Figure 1] 1 is a schematic diagram illustrating the principle of a method for measuring forest stand density according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will be described in detail below with reference to the accompanying drawings, but the description in this part is merely illustrative and interpretive and does not limit the scope of protection of the present invention. Furthermore, a person skilled in the art can combine the features in the embodiments and different embodiments of the present specification based on the description in the specification.

[0017] The embodiment of the present invention is as follows. With reference to FIG. 1, the method for measuring forest stand density is as follows: (1) determining a measurement area, determining an aircraft flight route, and setting the flight route passing through the measurement area as a congestion measurement sampling line; (2) Equipping the airplane with an active distance measurement module, starting up the active distance measurement module, the airplane performs flight and measurement according to the flight route, and vertically measures the distance from the active distance measurement module to the ground obstacle at multiple sampling points, that is, the distance of the laser distance measurement, and at the same time, the sampling point coordinates of the active distance measurement module storing TIFF2025503764000018.tif5170; (3) acquiring the measurement data of the airplane and solving the forest stand density of the measured area; (3.1) Sampling point coordinates of the active distance measurement module TIFF2025503764000019.tif5170 and takeoff point coordinates Compare TIFF2025503764000020.tif5170 and get the plane height value, defined as follows: TIFF2025503764000021.tif4170 formula, TIFF2025503764000022.tif4170 is the height of the plane, TIFF2025503764000023.tif4170 is the elevation value of the sampling point position, TIFF2025503764000024.tif7170 is the altitude value of the takeoff point position, step, (3.2) calculating the difference between the distance of the laser distance measurement of each sampling point and the height of the aircraft, and judging whether the difference is greater than a set threshold. If it is greater, the sampling point is determined to be unblocked; if it is not greater, the sampling point is determined to be blocked; (3.3) The steps include: summarizing the results of all sampling points, calculating the number of closed sampling points and the total number of sampling points, and dividing the number of closed sampling points by the total number of sampling points to obtain the forest stand closedness in the measurement area.

[0018] The present invention installs an on-board active distance measurement module on an airplane, and takes the flight route of the airplane to the sampling site or area to be measured as the measurement sampling line, calculates and measures the height from the active distance measurement module of the airplane to the ground obstacle, and compares the difference with the airplane's own height to judge the forest cover situation of the current sampling point, and finally calculates the forest cover degree by comprehensively stating the numerical values ​​of each sampling point on all the measurement sampling lines. The measurement accuracy of the present invention is reliable, the measurement speed is fast, and the measurement process is simple, and the measurement work of forest cover degree can be completed quickly in large quantities.

[0019] In addition to the above embodiment, in another embodiment of the present invention, in step (3.2), the threshold value is determined based on the measurement objective, and if only the density of the thorn forest is measured, the threshold value is the height of the highest shrub, and if the coverage of the thorn forest and the shrub forest is measured, the threshold value is the height of the highest ground cover.

[0020] In addition to the above embodiment, in another embodiment of the present invention, the specific steps of step (2) are as follows: (2.1) recording the measured take-off point coordinates of the active distance measurement module; (2.2) starting and flying the aircraft, measuring the current coordinates of the active distance measurement module, comparing the range of the area to be measured, and judging whether it enters the measurement area; (2.3) After entering the measurement area, at a set fixed time interval, the distance from the on-board active distance measurement module to the ground obstacle is measured vertically, the measurement point is the sampling point, and at the same time the sampling point coordinates of the active distance measurement module are stored.

[0021] Further, the calculation formula of the forest cover degree of the measurement area in step (3) is as follows: TIFF2025503764000025.tif29170

[0022] During the ceremony, TIFF2025503764000026.tif4170 is the forest stand density, TIFF2025503764000027.tif3170 is the number of sampling points to be compressed, TIFF2025503764000028.tif4170 is the total number of sampling points, TIFF2025503764000029.tif4170 is The congestion status of the sampling point of TIFF2025503764000030.tif4170, where 1 indicates congestion and 0 indicates no congestion. TIFF2025503764000031.tif4170 is is the distance of the laser distance measurement of the sampling point of TIFF2025503764000032.tif4170, TIFF2025503764000033.tif4170 is the threshold determined based on the measurement goal.

[0023] In addition to the above embodiment, in another embodiment of the present invention, the PCB circuit board of the active distance measuring module includes a microprocessor, a power supply module, an RTK module, a memory module, a data interface, a timer, a laser distance measuring module, and an indicator lamp, in which the microprocessor is used to complete calculation, storage, and control of data measurement, the power supply module is used to supply power to the microprocessor, the RTK module is used to obtain real-time spatial position coordinates of the active distance measuring module, the memory module is used to store the recorded data of the microprocessor, the data interface is used for development, testing, or field problem handling, the timer is used to provide high-precision timing, and the laser distance measuring module is used to measure the distance to an obstacle.

[0024] When the active distance measuring module is working, the microprocessor will according to the user's setting time interval requirement, obtain the current spatial position coordinate from the RTK module, obtain the current time from the timer, and obtain the current distance from the laser distance measuring module to the obstacle.

[0025] In addition to the above embodiment, in another embodiment of the present invention, the aircraft is a drone.

[0026] It should be noted that the above is merely a preferred embodiment of the present invention, and that those skilled in the art may make various improvements and modifications without departing from the spirit of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. The method for measuring forest stand density is as follows: (1) determining a measurement area, determining an aircraft flight route, and setting the flight route passing through the measurement area as a congestion measurement sampling line; (2) The airplane is equipped with an active distance measurement module, and the active distance measurement module is started. The airplane performs flight and measurement according to the flight route, and vertically measures the distance from the active distance measurement module to the ground obstacle at multiple sampling points, that is, the laser measurement distance, respectively, and simultaneously obtains the sampling point coordinates of the active distance measurement module storing the (3) obtaining the measurement data of the airplane and solving the forest stand density of the measured area; (3.1) Sampling point coordinates of the active distance measurement module and takeoff point coordinates to get the plane's height value, defined as: During the ceremony, is the height of the plane, is the elevation value of the sampling point location, is the altitude value of the takeoff point position, and (3.2) calculating the difference between the laser distance measurement distance of each sampling point and the height of the aircraft, judging whether the difference is greater than a set threshold, if it is, determining that this sampling point is not blocked, if it is not, determining that this sampling point is blocked; (3.3) Summarize the results of all sampling points, calculate the number of densified sampling points and the total number of sampling points, and divide the number of densified sampling points by the total number of sampling points to obtain the forest stand densification degree of the measurement area. A method for measuring forest stand density.

2. In step (3.2), the threshold value is determined based on the measurement objective. If only the forest cover is measured, the threshold value is the height of the highest shrub, and if both forest cover and shrub cover are measured, the threshold value is the height of the highest ground cover. A method for measuring forest stand density as claimed in claim 1.

3. The specific steps of step (2) are as follows: (2.1) recording the measured takeoff point coordinates of the active distance measurement module; (2.2) starting and flying the aircraft, measuring the current coordinates of the active distance measurement module, comparing the range of the area to be measured, and judging whether it enters the measurement area; (2.3) After entering the measurement area, at a set fixed time interval, vertically measure the distance from the on-board active distance measurement module to the ground obstacle, the measurement point is a sampling point, and at the same time, store the sampling point coordinates of the active distance measurement module; A method for measuring forest stand density as claimed in claim 1 or 2.

4. The calculation formula for the forest stand density of the measurement area in the step (3) is as follows: During the ceremony, is the stand density, is the number of sampling points to be condensed, is the total number of sampling points, is the The congestion status of the sampling point, where 1 represents congestion and 0 represents non-congestion. is the is the distance of the laser distance measurement of the sampling points of is the threshold determined based on the measurement goal A method for measuring forest stand density according to claim 3.

5. The PCB circuit board of the active distance measuring module includes a microprocessor, a power supply module, an RTK module, a memory module, a data interface, a timer, a laser distance measuring module and a lamp, the microprocessor is used to complete the calculation, storage and control of data measurement, the power supply module is used to provide power to the microprocessor, the RTK module is used to obtain the real-time spatial position coordinate of the active distance measuring module, the memory module is used to store the microprocessor recorded data, the data interface is used for development, testing or field problem handling, the timer is used to provide high-precision timing, and the laser distance measuring module is used to measure the distance to an obstacle. A method for measuring forest stand density as described in claim 4.

6. The aircraft is a drone A method for measuring forest stand density as described in claim 5.

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