A device and method for measuring grass cover

Abstract

The present application relates to a kind of grassland vegetation coverage measuring device and measuring method, device includes connecting column, lifting mechanism, host computer and camera, host computer is connected with lifting mechanism and camera communication;Connecting column includes vertical connection column and cross bar, column one end is fixed on ground, host computer is installed on column;Lifting mechanism includes lifting block and telescopic machine, the output shaft of telescopic machine connects lifting block, the top of lifting block is equipped with guide shaft, the one end of cross bar is equipped with with guide shaft cooperation installation guide hole, camera is connected with lifting block;Camera changes observation height according to vegetation type.Compared with prior art, the height of camera is controlled by lifting mechanism in the present application, when using, camera hangs under cross bar to collect information, when height needs to be adjusted, telescopic machine can be started by host computer or remote signal control, drive camera to rise or fall, so as to change the effect of camera height control collection range, and the measuring effect is better.

Description

Technical Field

[0001] This invention relates to vegetation cover collection, and more particularly to a grassland vegetation cover measurement device and method. Background Technology

[0002] Vegetation cover refers to the percentage of the vertical projection area of ​​the aboveground parts of a plant community or individual plants to the area of ​​a sample plot. It reflects the density of vegetation and the size of the area for photosynthesis. Vegetation cover is an important task in ecological monitoring and desertification monitoring, and it is also an effective index for assessing grassland and pasture conditions, land degradation, and desertification. Existing vegetation cover measurement devices typically consist of a L-shaped column with a main unit and solar panel mounted on the vertical pole, and a camera at the end of the top horizontal bar for analysis and measurement. However, the camera's flexibility is poor, affecting the measurement results.

[0003] A search revealed that authorization announcement number CN221483243U discloses a rapid grassland vegetation cover measurement device, specifically comprising: a storage box, an auxiliary measuring groove inside the storage box, an auxiliary measuring rod engaged inside the auxiliary measuring groove, a receiver slot inside the storage box, a receiver engaged inside the receiver slot, an auxiliary measuring fine-tuning plate on the auxiliary measuring rod, an adjusting hole on the outer surface of the first adjusting rod, an adjusting groove inside the second adjusting rod, a limiting plate slidably connected inside the adjusting groove, a telescopic column fixedly connected to one side of the limiting plate, an adjusting spring fixedly connected to the other side of the limiting plate, a motor fixedly connected inside the second adjusting rod, a rotating connecting plate fixedly connected to the motor drive end, and a connecting threaded hole on the top of the rotating connecting plate. However, this prior art cannot adapt to the dynamic changes in vegetation.

[0004] In summary, the technical problem that needs to be solved is how to design a grassland vegetation cover measurement device that can adapt to dynamic changes in vegetation. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art in terms of poor flexibility and to provide a grassland vegetation cover measuring device and method.

[0006] The objective of this invention can be achieved through the following technical solutions.

[0007] According to one aspect of the present invention, a grassland vegetation cover measuring device is provided, comprising a connecting column, a lifting mechanism, a main unit, and a camera, wherein the main unit is communicatively connected to the lifting mechanism and the camera; the connecting column comprises a vertical column and a horizontal bar connected perpendicularly to each other, one end of the vertical column is fixed to the ground, and the main unit is mounted on the vertical column; the lifting mechanism comprises a lifting block and a telescopic mechanism, wherein the output shaft of the telescopic mechanism is perpendicular to the ground and connected to the lifting block, the top of the lifting block is provided with a guide shaft, and the end of the horizontal bar away from the vertical column is provided with a guide hole that mates with the guide shaft; the camera is connected to the lifting block; the camera changes its observation height according to the vegetation type.

[0008] As a preferred technical solution, the lifting block is also equipped with a sensor, and the camera rises when the sensor detects an animal approaching.

[0009] As a preferred technical solution, a solar panel is also installed on the column, the solar panel is connected to a battery, and the battery is connected to the main unit, the lifting mechanism, and the camera.

[0010] As a preferred technical solution, one end of the crossbar is provided with a connecting block, and the connecting block has guide blocks on both sides, with guide holes set on the guide blocks; the two guide shafts are located on both sides of the camera, and connectors are detachably installed on the guide shafts, with the diameter of the connectors being larger than the diameter of the guide holes.

[0011] As a preferred technical solution, the telescopic mechanism is an electric push rod, a pneumatic cylinder, or a hydraulic cylinder.

[0012] As a preferred technical solution, the lifting mechanism further includes a flexible wiring hose containing a cable. The lifting block and the crossbar are provided with wiring holes. The two ends of the flexible wiring hose are respectively connected to the wiring holes on the lifting block and the crossbar. The flexible wiring hose is located on the side or side of the lifting block near the ground.

[0013] As a preferred technical solution, the connecting column further includes a supporting diagonal brace, which connects the upright column and the crossbar.

[0014] According to another aspect of the present invention, a measurement method for the grassland vegetation cover measuring device according to any one of claims 1 to 7 is provided, specifically comprising the following steps: Step S1: Obtain the current vegetation height and define a set distance between the camera and the vegetation. The target value for the camera height is the vegetation height plus the set distance. In step S2, the lifting mechanism adjusts the camera height according to the target camera height value, and the camera captures the current vegetation image and transmits it to the host. Step S3: Convert the current vegetation image to HSV space, set the vegetation color threshold, and the host performs color segmentation on the current vegetation image to obtain the total number of vegetation pixels and the total number of image pixels. The vegetation coverage is the percentage of vegetation pixels to the total number of image pixels.

[0015] As a preferred technical solution, the method for obtaining vegetation height specifically includes the following steps: Step S101: The camera's optical axis is perpendicular to the ground. It moves to a first height h1 and captures an image of the exposed ground at the first height. It then moves to a second height h2 and captures an image of the exposed ground at the second height, obtaining the ratios k1 and k2 between the pixel size and the actual size in the images at the first and second heights. In step S102, the camera's optical axis is perpendicular to the ground, and it moves to a first height h1 to capture a vegetation image at the first height; it moves to a second height h2 to capture a vegetation image at the second height; and the vegetation images at the first and second heights are transmitted to the host computer. Step S103: Calculate the actual vegetation height .

[0016] As a preferred technical solution, the target camera height is preset based on vegetation type and season: when the measuring device is located in a mixed vegetation of tall herbs and shrubs, the camera height is 2 meters in spring, 3 meters in summer, and 2.5 meters in autumn; when the measuring device is located in a forest-grassland composite system, the camera height is 5 meters; when the measuring device is located in an ecological station, the camera height is 6 meters; and when the measuring device is located in a grazing pasture, the camera height is higher during the grazing season than at other times.

[0017] Compared with the prior art, the present invention has the following beneficial effects.

[0018] 1) This invention controls the height of the camera through a lifting mechanism. When in use, the camera is hung below the crossbar to collect information. When the height needs to be adjusted, the telescopic mechanism can be started through the host or remote signal control, which will drive the camera to rise or fall together, thereby achieving the effect of changing the camera height to control the collection range and improve the measurement effect. The lifting mechanism only drives the camera and the lifting block, which is lighter. The connecting column, host and other parts do not move. Therefore, the lifting mechanism requires less driving force and has a smaller size. The guide shaft and guide hole cooperate to play a guiding and positioning role.

[0019] 2) This invention's sensor raises the camera when it detects an animal approaching, and automatically raises when it detects a risk of collision with an animal or external object. This design effectively avoids the risk of the camera being trampled, collided with, or damaged by humans, achieving automatic protection of the equipment without manual supervision, thus reducing maintenance costs and equipment wear and tear during field operations. The combination of solar panels and batteries utilizes solar energy to convert and store electrical energy, providing continuous power support for the main unit, lifting mechanism, and camera; solving the power supply problem in remote grasslands, pastoral areas, and other environments without mains power, eliminating dependence on external power sources.

[0020] 3) The connecting block of this invention can increase the size of the connection position of the telescopic machine, making it easier to install and providing more stable support. Both the guide shaft and the output shaft of the telescopic machine serve as guides and positions. The guide shaft slides on the guide block on the side of the connecting block, without interfering with the installation of the wiring inside the crossbar. The two guide shafts pass through the guide holes on both sides of the connecting block, avoiding the jamming and offset problems that are prone to occur with a single guide shaft, ensuring a smooth and precise camera lifting process; it also prevents the camera from rotating, making it more stable. The diameter of the connector is larger than the diameter of the guide hole. When the connection between the output shaft of the telescopic machine and the lifting block fails and becomes detached, or when the output shaft of the telescopic machine malfunctions and falls, the lifting block descends rapidly, and the connector will block it at the top of the lifting hole, preventing the guide shaft from falling further. This suspends the camera, preventing it from falling to the ground, making it safer and preventing damage to parts.

[0021] 4) The telescopic machine of this invention adopts an electric push rod. The electric push rod is easy to install, has a simple structure, and the telescopic distance is easier to control, more precise, and easy to adjust. Its output shaft can also be directly connected to the lifting block by means of shaft through connection, bolt connection, snap-fit, welding, etc. In addition, the lifting hole and the output shaft of the electric push rod can also act as a guide shaft, making it more stable.

[0022] 5) The connecting wire inside the crossbar of this invention passes through a flexible conduit and connects to the camera on the lifting block. The flexible conduit ensures that the connection remains open throughout the lifting process, resulting in greater stability. The flexible conduit is located on the side of the lifting block closest to the ground, preventing interference when the lifting block reaches its limit position and contacts the crossbar. The conduit's side placement also minimizes deformation during movement, making it more stable. Wiring holes are provided on the lifting block and crossbar for easy connection of the flexible conduit.

[0023] 6) The supporting diagonal bar of this invention can strengthen the crossbar and prevent it from bending.

[0024] 7) This invention first obtains the vegetation height and determines the target height of the camera, then adjusts the height for shooting and coverage calculation. The camera height is adjusted based on the actual vegetation height to ensure that the camera and vegetation maintain a reasonable set distance, avoiding the problem of vegetation exceeding the imaging range due to being too close or blurry imaging details due to being too far away. This significantly improves the accuracy and reliability of coverage measurement. By extracting vegetation pixels through HSV color space segmentation, it is more resistant to changes in lighting than RGB, and the calculation is simple and has a small amount of computation, which can quickly obtain vegetation coverage and meet the needs of rapid field measurement and real-time data feedback.

[0025] 8) This invention uses a dual-height imaging method. By obtaining the pixel ratios k1 and k2 at different heights, the actual vegetation height H is calculated using a formula. This eliminates the need to obtain a complete image of the entire plant, making the operation convenient.

[0026] 9) This invention presets the target height of the camera based on the vegetation type and growth period, reducing the need for manual intervention and accelerating the efficiency of batch field measurements. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of a grassland vegetation cover measuring device according to the present invention.

[0028] Figure 2 This is a partial exploded view of the lifting mechanism of the present invention.

[0029] Figure 3 For the present invention Figure 2 A magnified view of part A.

[0030] Figure 4 This is a schematic diagram of the lifting block of the present invention.

[0031] Figure 5 This is a flowchart of a grassland vegetation cover measurement method according to the present invention.

[0032] The numbers in the diagram are as follows: 1. Connecting column; 101. Upright column; 102. Horizontal bar; 1021. Guide hole; 1022. Connecting block; 1023. Guide block; 1024. Lifting hole; 103. Supporting diagonal bar; 2. Main unit; 3. Camera; 4. Lifting mechanism; 401. Lifting block; 4011. Guide shaft; 4012. Connector; 402. Telescopic mechanism; 403. Wiring hose. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] Example 1 like Figure 1 As shown in the figure, this embodiment provides a grassland vegetation cover measuring device, including a connecting column 1, a main unit 2, a camera 3, and a lifting mechanism 4.

[0035] The connecting column 1 is shaped like a figure 7, including a vertical column 101, a horizontal bar 102, and a supporting diagonal bar 103 connected perpendicularly at one end. The supporting diagonal bar 103 strengthens the horizontal bar 102 and prevents it from bending. Multiple supporting diagonal bars 103 can be installed for even stronger support. The main unit 2 and the solar panel are mounted on the vertical column 101. The solar panel is connected to a battery, which in turn connects to the main unit, the lifting mechanism, and the camera, providing power.

[0036] The lifting mechanism 4 includes a lifting block 401, a telescopic mechanism 402, and a flexible wiring hose 403. A camera 3 is installed at the bottom of the lifting block 401. The output shaft of the telescopic mechanism 402 reciprocates towards the ground. The output shaft of the telescopic mechanism 402 is connected to the top of the lifting block 401. The telescopic mechanism 402 is connected to the end of the crossbar 102 facing away from the column 101. Figure 4 As shown, the top of the lifting block 401 is provided with a guide shaft 4011, and the crossbar 102 is provided with a guide hole 1021 that is adapted to the guide shaft 4011.

[0037] like Figure 2 and Figure 3 As shown, a connecting block 1022 is provided at the end of the crossbar 102 facing away from the column 101. The telescopic mechanism 402 is connected to the crossbar 102 at the top of the connecting block 1022. The connecting block 1022 can increase the size of the connection position of the telescopic mechanism 402, making it easier to install the telescopic mechanism 402 and providing more stable support for the telescopic mechanism 402. The telescopic mechanism 402 and the connecting block 1022 can be connected by bolts or snap-fit.

[0038] A guide block 1023 is provided on the side of the connecting block 1022, and a guide hole 1021 is located on the guide block 1023. The guide shaft 4011 will slide in the guide block 1023 on the side of the connecting block 1022 without interfering with the installation of the wiring inside the crossbar 102. There are two guide blocks 1023, two guide holes 1021, and two guide shafts 4011, which are respectively set on both sides of the camera 3. The two guide shafts 4011 guide from both sides at the same time, which is more stable and more balanced, and prevents it from tilting and getting stuck on one side during the lifting process.

[0039] The top of the guide shaft 4011 is provided with a connector 4012 that can be detachably connected to it. The connector 4012 is larger than the guide hole 1021. When the connection between the output shaft of the telescopic machine 402 and the lifting block 401 fails or the output shaft of the telescopic machine 402 falls, the lifting block 401 descends rapidly. Then the connector 4012 will block the top of the lifting hole 1024, preventing the guide shaft 4011 from falling further. This can hold the camera 3, preventing it from falling to the ground, making it safer and preventing damage to parts.

[0040] The connector 4012 is a nut that is threaded to the top of the guide shaft 4011. An external thread can be machined on the top of the guide shaft 4011 to avoid the thread interfering with the stability of the hole-shaft fit. This allows the nut to be directly screwed onto the connecting guide shaft 4011, making installation convenient.

[0041] The two ends of the flexible conduit 403 are connected to the lifting block 401 and the crossbar 102, respectively, and the conduit contains a cable. The connecting wire inside the crossbar 102 passes through the flexible conduit 403 and connects to the wiring hole on the camera 3 on the lifting block 401. The flexible conduit 403 ensures that the connection remains open during lifting, making it more stable. The connection point between the flexible conduit 403 and the lifting block 401 is located on the side of the lifting block 401. By not placing the flexible conduit 403 on the top surface of the lifting block 401, it avoids interference when the lifting block 401 reaches its limit position and is in contact with the crossbar 102, resulting in more stable movement. Holes can be drilled on the lifting block 401 and the crossbar 102 for easy connection of the flexible conduit 403. Placing it on the side reduces deformation during movement, further enhancing stability.

[0042] When the device is in use, camera 3 is hung below crossbar 102 to collect information. When the height needs to be adjusted, the telescopic mechanism 402 can be started via host 2 or remote signal control. The output shaft of telescopic mechanism 402 moves, pushing or pulling the lifting block 401 out. This causes the lifting block 401 to move up or down, which can drive the camera 3 connected to its bottom to rise or fall together, thereby changing the height of camera 3 to control the collection range and improve the measurement effect. Moreover, when the lifting mechanism 4 is driven, only the camera 3 and the lifting block 401 are driven, resulting in lower weight. The connecting column 1, host 2, solar panel and other parts do not move. Therefore, the lifting mechanism 4 requires less driving force and has a smaller size. The lifting block 401 is also equipped with a guide shaft 4011 inserted into the guide hole 1021. The two work together to achieve the effect of guidance and positioning. The guide shaft 4011 and the output shaft of telescopic mechanism 402 work together to connect and support the two shafts, which can prevent the lifting block 401 from rotating, making it more stable.

[0043] The telescopic mechanism 402 is an electric actuator, and the crossbar 102 has a lifting hole 1024 that matches the output shaft of the electric actuator. Using an electric actuator is convenient to install, has a simple structure, and allows for easier and more precise control of the telescopic distance, facilitating adjustment. Its output shaft can also be directly connected to the lifting block 401 via a shaft-through connection, bolt connection, snap-fit, welding, or other methods. Furthermore, the lifting hole 1024 and the output shaft of the electric actuator also act as a guide shaft 4011, enhancing stability. The telescopic mechanism 402 can also use either a pneumatic cylinder or a hydraulic cylinder; pneumatic cylinders are suitable for scenarios requiring high response speed, while hydraulic cylinders are suitable for heavy loads and areas with large mixed shrubs, improving the flexibility and customization capabilities of the device.

[0044] Example 2 like Figure 5 As shown in the figure, this embodiment provides a method for measuring grassland vegetation cover, as detailed below.

[0045] The current vegetation height is obtained, and a set distance is defined between camera 3 and the vegetation. The target height of camera 3 is the vegetation height plus the set distance. The vegetation height acquisition process is as follows: the optical axis of camera 3 is perpendicular to the ground, and it moves to the first height h1 to capture an image of the bare ground at the first height; it moves to the second height h2 to capture an image of the bare ground at the second height. Since the pixel size of the same object in the image is proportional to the shooting height, the ratio k1 and k2 of the pixels to the actual size in the images at the first height and the second height can be obtained. , Camera 3, with its optical axis perpendicular to the ground, moves to a first height h1 to capture an image of vegetation at that height; it then moves to a second height h2 to capture an image of vegetation at that height; these images are then transmitted to host 2; the distance from the top of the vegetation to camera 3 determines the imaging scale. Let H be the actual vegetation height, and H be the calibration constant for camera 3; eliminate The actual vegetation height can be obtained. .

[0046] The lifting mechanism 4 adjusts the height of the camera 3 according to the target height value of the camera 3, and the camera 3 captures the current vegetation image and transmits it to the host 2; Convert the current vegetation image to HSV space (separating the color itself, intensity, and brightness, suitable for color extraction; for example, the H green range can be fixed for vegetation, and vegetation and ground can be accurately separated in different weather and lighting environments). Set the vegetation color threshold, host 2 performs color segmentation on the current vegetation image, and obtains the total number of vegetation pixels and the total number of image pixels. The vegetation coverage is the percentage of vegetation pixels to the total number of image pixels.

[0047] The target height of camera 3 is preset based on vegetation type and season: when monitoring tall herbaceous and shrub mixed vegetation, the column 101 can be set to a height of about 3 meters. In spring, when plants are budding and sprouting new branches, their height is usually less than 50 centimeters. At this time, the height of camera 3 can be lowered to about 2 meters by lifting mechanism 4 for observation and data collection. In summer, when plants enter a rapid growth period and grow to about 2 meters, camera 3 can be raised to the top 3 meters for observation and data collection. Then in autumn, when plants begin to wither and some fall over, camera 3 can be lowered to about 2.5 meters for observation and data collection.

[0048] Similarly, if used in a forest-grassland composite system, the height of column 101 can be set to about 5 meters. For long-term dynamic monitoring of large sample plots such as ecological stations, it can be set to about 6 meters. The height of camera 3 can be changed according to the height of the corresponding plants in spring, summer and autumn, so that camera 3 is always in the best observation position for measurement in different seasons and different vegetation conditions, resulting in better measurement results.

[0049] If it is set up on a pasture, the camera 3 can be raised to a certain height during the grazing season to prevent cattle, sheep and other livestock from bumping into or jumping on the camera 3 when passing by. A time switch can also be set to raise the camera 3 at a set time, or an infrared sensor or other sensor can be set to automatically raise the camera 3 when livestock approach.

[0050] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A grassland vegetation cover measuring device, characterized in that, The system includes a connecting column (1), a lifting mechanism (4), a main unit (2), and a camera (3). The main unit (2) is communicatively connected to the lifting mechanism (4) and the camera (3). The connecting column (1) includes a vertical column (101) and a horizontal bar (102) that are perpendicularly connected to each other. One end of the vertical column (101) is fixed to the ground, and the main unit (2) is installed on the vertical column (101). The lifting mechanism (4) includes a lifting block (401) and a telescopic mechanism (402). The output shaft of the telescopic mechanism (402) is perpendicular to the ground and connected to the lifting block (401). The top of the lifting block (401) is provided with a guide shaft (4011). The end of the horizontal bar (102) away from the vertical column (101) is provided with a guide hole (1021) that is installed in conjunction with the guide shaft (4011). The camera (3) is connected to the lifting block (401). The camera (3) changes its observation height according to the vegetation type.

2. The grassland vegetation cover measuring device according to claim 1, characterized in that, The lifting block (401) is also equipped with a sensor, and the camera (3) rises when the sensor detects that an animal is approaching.

3. The grassland vegetation cover measuring device according to claim 1, characterized in that, A solar panel is also installed on the column (101), the solar panel is connected to a storage battery, and the storage battery is connected to the host (2), the lifting mechanism (4) and the camera (3).

4. The grassland vegetation cover measuring device according to claim 1, characterized in that, The crossbar (102) has a connecting block (1022) at one end, and guide blocks (1023) on both sides of the connecting block (1022). The guide hole (1021) is set on the guide block (1023). The two guide shafts (4011) are located on both sides of the camera (3). A connector (4012) is detachably installed on the guide shaft (4011). The diameter of the connector (4012) is larger than the diameter of the guide hole (1021).

5. The grassland vegetation cover measuring device according to claim 1, characterized in that, The telescopic mechanism (402) is an electric push rod, a pneumatic cylinder, or a hydraulic cylinder.

6. The grassland vegetation cover measuring device according to claim 1, characterized in that, The lifting mechanism (4) further includes a wiring hose (403), which contains a cable. The lifting block (401) and the crossbar (102) are provided with wiring holes. The two ends of the wiring hose (403) are respectively connected to the wiring holes on the lifting block (401) and the crossbar (102). The wiring hose (403) is located on the side or side of the lifting block (401) near the ground.

7. The grassland vegetation cover measuring device according to claim 1, characterized in that, The connecting column (1) further includes a support diagonal rod (103), which connects the column (101) and the crossbar (102).

8. A measurement method for the grassland vegetation cover measuring device according to any one of claims 1 to 7, characterized in that, Specifically, the following steps are included: Step S1: Obtain the current vegetation height and define the set distance between the camera (3) and the vegetation. The target value of the camera (3) height is the vegetation height plus the set distance. In step S2, the lifting mechanism (4) adjusts the height of the camera (3) according to the target height value of the camera (3), and the camera (3) captures the current vegetation image and transmits it to the host (2). Step S3: Convert the current vegetation image to HSV space, set the vegetation color threshold, and the host (2) performs color segmentation on the current vegetation image to obtain the total number of vegetation pixels and the total number of image pixels. The vegetation coverage is the percentage of vegetation pixels to the total number of image pixels.

9. The measurement method according to claim 8, characterized in that, The method for obtaining vegetation height specifically includes the following steps: Step S101: The optical axis of the camera (3) is perpendicular to the ground. It moves to the first height h1 and takes an image of the bare ground at the first height. It moves to the second height h2 and takes an image of the bare ground at the second height. The ratios k1 and k2 of the pixel size to the actual size in the images at the first and second heights are obtained. In step S102, the optical axis of the camera (3) is perpendicular to the ground, and it moves to the first height h1 to capture a vegetation image at the first height; it moves to the second height h2 to capture a vegetation image at the second height; and the vegetation images at the first and second heights are transmitted to the host (2). Step S103: Calculate the actual vegetation height .

10. The measurement method according to claim 8, characterized in that, The target height of the camera (3) is preset according to the vegetation type and period: when the measuring device is located in a mixed plant of tall herbaceous and shrub plants, the height of the camera (3) is 2 meters in spring, 3 meters in summer, and 2.5 meters in autumn; when the measuring device is located in a forest-grassland composite system, the height of the camera (3) is 5 meters; when the measuring device is located in an ecological station, the height of the camera (3) is 6 meters; when the measuring device is located in a grazing pasture, the height of the camera (3) is higher during the grazing period than at other times.

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