Device and method for measuring vertical projection coverage and silhouette coverage of herbaceous plant

Abstract

The invention relates to a device and a method for measuring vertical projection coverage and side shadow coverage of herbaceous plants. The measuring device comprises a square frame, a vertical rod, an L-shaped arm rod, a background plate, a partition plate, a camera and a mobile phone. The square frame is used for delineating herbaceous plants to be shot on a quadrat selected in a field measured place, the L-shaped arm rod is arranged on one frame of the square frame, the vertical rod is arranged at the midpoint position of the frame, opposite to the frame connected with the L-shaped arm rod, of the square frame, the background plate is vertically arranged on the frame, provided with the L-shaped arm rod, of the square frame, and the background plate is arranged on the square frame. The partition plate is arranged at the midpoint position of the other group of opposite borders of the square frame, and the camera is provided with a multispectral lens and a communication module; digital image processing software and an APP for calculating the vertical projection coverage and the side shadow coverage of the plant are arranged in the mobile phone, and the mobile phone is used for controlling the camera to shoot the vertical projection and the side shadow of the plant, receiving the picture shot by the camera and calculating the vertical projection coverage and the side shadow coverage of the plant by utilizing the APP.

Description

Technical Field

[0001] The invention relates to a device for measuring plant projection coverage, in particular to a device and method for measuring vertical projection coverage and silhouette coverage of herbaceous plants. Background Art

[0002] Herbaceous plants are widely distributed in wind erosion areas and are the main vegetation type that affects soil wind erosion. Soil wind erosion is essentially a continuous dynamic process of the interaction between wind erosion force, roughness interference force and soil anti-erosion force. Plants are the most common and important roughness factor, which profoundly affects soil wind erosion by directly covering the surface, changing the airflow field, intercepting and capturing wind erosion particles, etc. Early studies focused on the impact of direct vegetation coverage on soil wind erosion, and established multiple empirical relationships between vegetation coverage (vertical projection coverage) and soil wind erosion. In wind erosion models such as the wind erosion equation WEQ and the modified wind erosion equation RWEQ, plant vertical projection coverage is often used to express the impact of vegetation on wind erosion. Recent studies have shown that the key to plant influence on soil wind erosion is the change in the airflow field. Since the airflow passes through the plant laterally, the plant silhouette cover is considered to be better than the vertical projection cover to characterize the vegetation's blocking effect on airflow and its impact on wind erosion. More and more studies have shown that the impact of plant silhouette cover should be considered more in wind erosion models. Therefore, the measurement of plant silhouette cover becomes the key to expressing the role of vegetation in affecting wind erosion and improving soil wind erosion prediction. However, existing measuring instruments and equipment can only measure the vertical projection cover of plants, but cannot be used to measure the silhouette cover of plants. Summary of the invention

[0003] The purpose of the present invention is to provide a device and method for measuring the vertical projection cover and silhouette cover of herbaceous plants, so as to solve the problem that the existing measuring instruments cannot measure the silhouette cover of plants.

[0004] The object of the present invention is achieved in that: A device for measuring vertical projection coverage and silhouette coverage of herbaceous plants, comprising: The square frame is a square frame used to carry the device components and circle the herbaceous plants to be photographed on the sample plot selected in the field; The L-arm is an inverted L-shaped rod frame, the lower end of which is arranged at the midpoint of a frame of the square frame, and the upper horizontal section thereof extends to the upper space of the square frame; The background plate is a rectangular flat plate, which is vertically arranged on the frame where the L-arm bar is arranged on the square frame and is fixedly connected to the L-arm bar and is used as a background baffle for photographing the silhouette area of ​​the plant; A vertical rod, the lower end of which is arranged at the midpoint of a frame on the square frame opposite to the frame connected to the L-arm rod; A camera with a multi-spectral lens and a communication module capable of wirelessly communicating with a mobile phone, for capturing the vertical projection and silhouette of the plants within the square frame; The fixing device is a camera fixing part, which is used to fix the camera on the horizontal section of the L-arm rod to photograph the vertical projection of the plant, or to fix the camera on the vertical rod to photograph the silhouette area of ​​the plant; The partition plate has two lower corners disposed at the midpoint of another set of opposite frames of the square frame, and is used to press down the plants near the vertical pole in the square frame to clear obstacles in front of the camera lens, making it easier for the camera to shoot the silhouette area of ​​the plants; and The mobile phone has built-in digital image processing software and an APP for calculating the vertical projection cover and silhouette cover of plants. The mobile phone is used to control the camera to shoot the vertical projection and silhouette of plants, receive the photos taken by the camera, and use the APP to calculate the vertical projection cover and silhouette cover of plants.

[0005] Furthermore, bayonet holes are respectively provided at the outer edges of the midpoints of the frames of a group of opposite sides of the square frame for connecting the L-arm rod or the vertical rod.

[0006] Furthermore, the upright section of the L-arm rod is a straight rod or a telescopic rod.

[0007] Furthermore, a longitudinal slot is provided on the back side of the background plate along the longitudinal center line of the plate surface for inserting the L-arm rod.

[0008] Furthermore, the fixer is provided with a claw for clamping the camera on the front side of the slot plate, and a slot for inserting the horizontal section of the vertical pole or the L-arm rod on the back side of the slot plate.

[0009] Furthermore, laterally extending latches are respectively connected to the two corners of the bottom of the partition, and a ring for receiving the latches is provided on the top surface of the grooved card plate with the groove facing downward, and the grooved card plate is clamped on the frame of the square frame to realize the rotational connection of the partition.

[0010] The measuring device of the present invention utilizes the multispectral lens of the camera to take vertical projection photos of herbaceous plants and photos of the silhouette area of ​​the plants, and processes the taken photos through digital image processing software to obtain a normalized vegetation index map and classification thresholds of the normalized vegetation index of plants and non-plants, and then uses a special APP to calculate the plant vertical projection cover and the plant silhouette cover, thereby realizing the rapid determination of the height, vertical projection cover and silhouette cover of herbaceous plants, and providing a favorable measure for field surveys of soil wind erosion related research.

[0011] The measuring device of the present invention has a simple structure, is easy to carry and assemble, and is particularly suitable for field work. The design and use of a dedicated APP realizes the preprocessing of vertical projection photos and silhouette area photos of plants, band calculation, and automation of vertical projection cover and silhouette cover calculation, thereby ensuring the accuracy of vertical projection cover and silhouette cover calculation and improving measurement efficiency.

[0012] The purpose of the present invention can also be achieved like this: A method for measuring vertical projection coverage and silhouette coverage of herbaceous plants comprises the following steps: S1. Set up a device for measuring the vertical projection cover and the silhouette cover of herbaceous plants according to the present invention.

[0013] S2. Selection of sample plots and taking of vertical projection photos: Select a place representing the normal growth conditions of herbaceous plants in the measured area as the sample plot, place the square frame of the measuring device in the central area of ​​the sample plot, and then plug the L-arm rod into the square frame. Establish a connection between the mobile phone and the camera through the communication module, and install the camera on the horizontal section of the L-arm rod through the fixture. Aim the camera lens at the plants in the square frame, and use the mobile phone to control the camera to take vertical projection photos of the plants.

[0014] S3. Taking photos of the silhouette area of ​​plants in the sample plot: remove the L-arm rod, camera and holder from the square frame, install the background board on the L-arm rod, and then install the L-arm rod on the square frame to measure the average height of the plants in the sample plot; install the vertical pole on the square frame, and install the camera on the vertical pole through the holder. The height of the camera lens is half of the average height of the plants; lower the partition vertically to the middle of the frame on the square frame, press down the plants on the side of the vertical pole in the square frame to clear obstacles in front of the camera lens, and use the mobile phone to control the camera to take photos of the silhouette area of ​​the plants.

[0015] S4. Calculation of plant vertical projection cover: Import the taken vertical projection photos of plants into the digital image processing software in the mobile phone, and obtain the normalized vegetation index map and the classification thresholds of the normalized vegetation index of plants and non-plants after processing; the APP for calculating the vertical projection cover and silhouette cover of plants classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, and calculates the vertical projection cover of plants based on this.

[0016] S5. Calculation of plant silhouette cover: Import the photographs of the silhouette area of ​​the sample plot plants into the digital image processing software in the mobile phone, and obtain the normalized vegetation index map and the classification thresholds of the normalized vegetation index of plants and non-plants after processing; the APP for calculating the vertical projection cover and silhouette cover of plants classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, and calculates the plant silhouette cover based on this.

[0017] Furthermore, the average height of the plants in the sample plot is measured by measuring the heights of no less than 10 plants in the sample plot, and calculating the average height of all the measured plants as the average height of the plants.

[0018] Furthermore, the specific processing method of step S4 is: first import the vertical projection photo of the plant taken by the camera into the digital image processing software in the mobile phone, select NDVI to calculate and obtain the normalized vegetation index map; import the normalized vegetation index map and the vertical projection photo of the plant into the ArcGIS software for superimposed display, when the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the normalized vegetation index of plants and non-plants; input the determined classification threshold into the APP for calculating the vertical projection cover and silhouette cover of the plant, and the APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which plant pixels are assigned a value of 1 and non-plant pixels are assigned a value of 0; enter the plant vertical projection cover calculation interface in the APP program, and calculate the plant vertical projection area according to the binary image. S v : S v = n × A in, n is the number of plant pixels in the sample plot; A is the pixel size; Then calculate the vertical projection coverage of the plant based on the vertical projection area of ​​the plant F v : F v =( S v ÷ W )×100% in, W is the area of ​​the sample plot.

[0019] Furthermore, the specific method of step S5 is: first import the sample plot plant silhouette area photo taken by the camera into the digital image processing software in the mobile phone, select NDVI to calculate and obtain the normalized vegetation index map; import the normalized vegetation index map and the sample plot plant silhouette area photo into the ArcGIS software for superimposed display, when the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the plant and non-plant normalized vegetation index; input the determined classification threshold into the APP for calculating the vertical projection cover and silhouette cover of the plant, and the APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which plant pixels are assigned a value of 1 and non-plant pixels are assigned a value of 0; enter the plant silhouette cover calculation interface in the APP program, and calculate the plant silhouette area according to the binary image. S l : S l =( m × A )+ L in, m is the number of plant pixels; A is the pixel size; L is the distance between the lower end of the partition and the background board; Then calculate the plant silhouette coverage based on the plant silhouette area λ c : λ c =( S l ÷ W )×100% in, W is the area of ​​the sample plot.

[0020] The measuring method of the present invention realizes the preprocessing of plant vertical projection photos and silhouette area photos, band calculation and automation of vertical projection cover and silhouette cover calculation, ensures the accuracy of vertical projection cover and silhouette cover calculation and improves measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the measuring device of the present invention.

[0022] Figure 2 It is a structural diagram of a square frame.

[0023] Figure 3 It is a structural diagram of the background board.

[0024] Figure 4 It is a schematic diagram of the structure of the partition.

[0025] Figure 5 It is a schematic diagram of the structure of the fixator.

[0026] Figure 6 It is a program calculation flow chart.

[0027] In the figure: 1. square frame, 2. vertical pole, 3. L-arm pole, 4. background board, 5. partition, 6. camera, 7. holder. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1 As shown, the measuring device of the present invention comprises a square frame 1, a vertical pole 2, an L-arm rod 3, a background plate 4, a partition 5, a camera 6, a holder 7 and a mobile phone (not shown). The square frame 1, the vertical pole 2 and the L-arm rod 3 are all made of aluminum alloy, which is light in weight, high in hardness, low in cost, easy to process, and convenient to carry, and can meet the working requirements of field measurement.

[0030] like Figure 2 As shown, the square frame 1 is a square frame with an inner side length of 1m×1m, and the width of the four frames is 2.0cm. A bayonet is provided at the outer edge of the midpoint of a set of frames of opposite sides of the square frame 1, one bayonet is used to connect the L arm 3, and the other bayonet is used to connect the vertical pole 2. The top surface of the other set of frames of the square frame 1 is marked with a scale, and the accuracy of the scale is 1cm. The bayonet can also be replaced with a plug-in column.

[0031] Figure 1 In the figure, the vertical pole 2 is a 1.0m long straight arm pole, the lower end of which is a plug connector that matches the bayonet on the square frame and can be directly plugged into the bayonet of the square frame 1. For the plug-in column on the square frame, the lower end of the vertical pole made of square tube can be directly used to socket and match it. A scale is made on the vertical pole 2, and the accuracy of the scale is 1cm. The L arm rod 3 is a 2.0m long inverted L-shaped rod frame. The upright section of the L arm rod 3 can be a straight rod, but it is best to be made into a telescopic rod for easy carrying. The length of the horizontal section of the L arm rod 3 is 0.5m. After the lower end of the upright section of the L arm rod 3 is connected to the square frame 1, the horizontal section above it extends into the upper space of the square frame.

[0032] like Figure 1 , Figure 3 As shown, the background plate 4 is a 1m×1m white plastic plate, with scales on both sides of the background plate 4. The background color of the scale is yellow, the scale lines and scale numbers are black, and the scale accuracy is 1cm. A longitudinal slot is provided on the back of the background plate 4 along the longitudinal center line of the plate surface. When the background plate 4 is plugged into the L arm 3 and the L arm 3 is plugged into the square frame 1, the bottom edge of the background plate 4 contacts the frame of the square frame 1.

[0033] like Figure 1 , Figure 4 As shown, the partition 5 is a thin iron plate of 1m×1m, and can also be made into a telescopic plate with two sections. A grooved card is rotatably connected to the two lower corners of the partition 5. The groove of the grooved card faces downward and can be clamped on the frame of the square frame 1. The rotation connection between the partition 5 and the grooved card can be adopted Figure 4 The circular ring connection method shown is that holes are respectively opened at the two lower corners of the partition 5, and circular rings are inserted therethrough, and the circular rings are connected to the top surface of the groove-shaped card plate. A bolt connection method can also be adopted, that is, horizontally extending bolts are respectively connected to the two corners of the bottom of the partition 5, and a sleeve ring for receiving the bolts is provided on the top surface of the groove-shaped card plate, thereby realizing the rotation connection of the partition 5.

[0034] like Figure 1 , Figure 5 As shown, the holder 7 is a clamping claw for clamping the camera on the front of a slot plate, and the clamping claw can adopt the structure of a car-mounted mobile phone clamp; a slot is provided on the back of the slot plate for plugging into the vertical pole 2 or the horizontal section of the L arm 3. The holder 7 is a fixing part of the camera 6, which is used to fix the camera 6 on the horizontal section of the L arm 3 to shoot the vertical projection of the plant, or to fix the camera 6 on the vertical pole 2 to shoot the silhouette area of ​​the plant.

[0035] The camera 6 is equipped with a multi-spectral lens and a communication module capable of wireless communication with a mobile phone. The multi-spectral camera includes four bands: red, green, blue, and near-infrared. The pixel is more than 1.3 million, supports auto focus, and the focus distance is 0.5~2.0m. The communication module can transmit wireless signals with the mobile phone.

[0036] like Figure 1 , Figure 6 As shown, the measuring method of the present invention comprises the following steps: Step 1: Select the sample plot and take vertical projection photos.

[0037] In the measured area, select a location where the herbaceous plant types have relatively uniform growth and can represent the normal conditions of the herbaceous plants in the measured area as a vegetation sample plot. For the herbaceous sample plot, select a sample plot area of ​​2m×2m, and place the square frame 1 of the measuring device of the present invention in the central area of ​​the sample plot, with the center of the square frame 1 and the center of the sample plot overlapping as much as possible. Then plug the L-arm 3 into the square frame 1, and establish a connection between the mobile phone and the camera 6 through the communication module to ensure that the mobile phone can remotely control the camera 6 to take pictures; and install the camera 6 on the horizontal section of the L-arm 3 through the fixture 7. The multispectral lens of the camera 6 is located on the normal of the square frame 1, aimed at the plants in the square frame 1, and the camera 6 is controlled by the mobile phone to take vertical projection photos of the plants in the sample plot.

[0038] Step 2: Take photos of the silhouette area of ​​the plants in the sample plot.

[0039] Remove the L-arm rod 3 from the square frame 1, and remove the camera 8 and the holder 7, install the background plate 4 on the L-arm rod 3, and then install the L-arm rod 3 on the square frame 1, and measure the average height of the plants in the sample plot by the scale on the background plate 4. The specific measurement method is: measure the height of no less than 10 plants in the sample plot, calculate the average height of all measured plants, and use it as the average height of the plants. Install the vertical pole 2 on the square frame 1, and install the camera 6 on the vertical pole 2 through the holder 7, and the lens height of the camera 6 is half of the average height of the plants. Vertically lower the partition 5 to the middle position of the frame on the square frame 1, and press down the plants on the side of the vertical pole 2 in the square frame 1 to clear the obstacles in front of the camera lens. Then control the camera 6 through the mobile phone to take a photo of the silhouette area of ​​the plants in the sample plot.

[0040] Step three: Calculation of plant vertical projection cover.

[0041] First, import the photographs of the vertical projection of plants into the digital image processing software in the mobile phone, and select NDVI to calculate the normalized vegetation index map. Import the normalized vegetation index map and the vertical projection photos of plants into the ArcGIS software for superimposed display. The normalized vegetation index map is divided into two categories: high value and low value, and the high value category is transparent display. When the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the normalized vegetation index of plants and non-plants. Input the determined classification threshold into the APP for calculating the vertical projection cover and silhouette cover of plants. The APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which plant pixels are assigned a value of 1 and non-plant pixels are assigned a value of 0. Enter the plant vertical projection cover calculation interface in the APP program, and calculate the plant vertical projection area based on the binary image. S v : S v = n × A in, n is the number of plant pixels in the sample plot; A is the pixel size.

[0042] Then calculate the vertical projection coverage of the plant based on the vertical projection area of ​​the plant F v : F v =( S v ÷ W )×100% in,W is the area of ​​the sample plot.

[0043] Step 4: Calculation of vegetation silhouette coverage.

[0044] First, import the sample plot plant silhouette area photos taken by the camera into the digital image processing software in the mobile phone, and select NDVI to calculate the normalized vegetation index map; import the normalized vegetation index map and the sample plot plant silhouette area photos into ArcGIS software for superimposed display. The normalized vegetation index map is divided into two categories: high value and low value, and the high value category is transparent display. When the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the normalized vegetation index of plants and non-plants. The determined classification threshold is input into the APP for calculating the vertical projection cover and silhouette cover of plants. The APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which plant pixels are assigned a value of 1 and non-plant pixels are assigned a value of 0. Enter the plant silhouette cover calculation interface in the APP program and calculate the plant silhouette area based on the binary image. S l : S l =( m × A )+ L in, m is the number of plant pixels; A is the pixel size; L It is the distance between the lower end of the partition and the background board.

[0045] Then calculate the plant silhouette coverage based on the plant silhouette area λ c : λ c =( S l ÷ W )×100% in, W is the area of ​​the sample plot.

[0046] When taking photos of the silhouette area of ​​the sample plot plants, the main considerations are the shooting height and the shooting width of the plants. The shooting height of the silhouette area of ​​the sample plot plants can be adjusted according to the average height of the herbaceous plants in the sample plot, and the best position of the camera lens is set at 1 / 2 of the average height of the herbaceous plants. The shooting plant width can be adjusted by the area of ​​the square frame 1 covered by the plants separated by the partition 5. The lower end of the partition 5 is set in the middle position of the square frame 1 to press down the plants between the partition 5 and the vertical pole 2, which is convenient for shooting the silhouette area of ​​the sample plot plants. The setting position of the partition 5 on the square frame 1 is adjusted according to the density of the herbaceous plants in the sample plot to ensure that the branches and leaves of the herbaceous plants do not block each other during shooting.

Claims

1. A device for measuring vertical projection coverage and silhouette coverage of herbaceous plants, characterized in that: include: The square frame is a square frame used to carry the device components and circle the herbaceous plants to be photographed on the sample plot selected in the field; The L-arm is an inverted L-shaped rod frame, the lower end of which is arranged at the midpoint of a frame of the square frame, and the upper horizontal section thereof extends to the upper space of the square frame; The background plate is a rectangular flat plate, which is vertically arranged on the frame where the L-arm bar is arranged on the square frame and is fixedly connected to the L-arm bar and is used as a background baffle for photographing the silhouette area of ​​the plant; A vertical rod, the lower end of which is arranged at the midpoint of a frame on the square frame opposite to the frame connected to the L-arm rod; A camera with a multi-spectral lens and a communication module capable of wirelessly communicating with a mobile phone, for capturing the vertical projection and silhouette of the plants within the square frame; The fixing device is a camera fixing part, which is used to fix the camera on the horizontal section of the L-arm rod to photograph the vertical projection of the plant, or to fix the camera on the vertical rod to photograph the silhouette area of ​​the plant; The partition plate, whose lower two corners are arranged at the midpoint of another set of opposite frames of the square frame, is used to press down the plants near the vertical pole in the square frame to clear the obstacles in front of the camera lens, so as to facilitate the camera to shoot the silhouette area of ​​the plants; as well as The mobile phone has built-in digital image processing software and an APP for calculating the vertical projection cover and silhouette cover of plants. The mobile phone is used to control the camera to shoot the vertical projection and silhouette of plants, receive the photos taken by the camera, and use the APP to calculate the vertical projection cover and silhouette cover of plants.

2. The device for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 1, characterized in that: A bayonet is respectively arranged at the outer edge of the midpoint of the frame of a group of opposite sides of the square frame, which is used to connect the L arm rod or the vertical rod.

3. The device for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 1, characterized in that: The upright section of the L-arm rod is a straight rod or a telescopic rod.

4. The device for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 1, characterized in that: On the back side of the background plate, a longitudinal slot is arranged along the longitudinal center line of the plate surface for inserting the L arm rod.

5. The device for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 1, characterized in that: The fixing device is provided with a clamping claw for clamping the camera on the front side of the slot plate, and a slot for inserting the horizontal section of the vertical pole or the L-arm pole on the back side of the slot plate.

6. The device for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 1, characterized in that: Two corners of the bottom of the partition are respectively connected with transversely extending latches, and a sleeve ring for receiving the latches is arranged on the top surface of the grooved card plate with the notch facing downward, and the grooved card plate is clamped on the frame of the square frame.

7. A method for measuring vertical projection coverage and silhouette coverage of herbaceous plants, characterized in that: The following steps are involved: S1. A device for measuring the vertical projection coverage and the silhouette coverage of herbaceous plants as described in any one of claims 1 to 6 is provided; S2. Selection of sample plots and taking of vertical projection photos: Select a place representing the normal growth conditions of herbaceous plants in the measured area as a sample plot, place the square frame of the measuring device in the central area of ​​the sample plot, plug the L-arm rod into the square frame, establish a connection between the mobile phone and the camera through the communication module, and install the camera on the horizontal section of the L-arm rod through a fixture, aim the camera lens at the plants in the square frame, and use the mobile phone to control the camera to take vertical projection photos of the plants; S3. Taking photos of the silhouette area of ​​the plants in the sample plot: remove the L-arm rod from the square frame, remove the camera and the holder, install the background plate on the L-arm rod, and then install the L-arm rod on the square frame to measure the average height of the plants in the sample plot; install the vertical pole on the square frame, and install the camera on the vertical pole through the holder, and the height of the camera lens is half of the average height of the plants; vertically lower the partition plate to the middle of the frame on the square frame, press down the plants on the side of the vertical pole in the square frame to clear the obstacles in front of the camera lens, and control the camera with a mobile phone to take photos of the silhouette area of ​​the plants; S4. Calculation of plant vertical projection cover: Import the photographed plant vertical projection photos into the digital image processing software in the mobile phone, and obtain the normalized vegetation index map and the classification threshold of the normalized vegetation index of plants and non-plants after processing; the APP for calculating the plant vertical projection cover and silhouette cover classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, and calculates the plant vertical projection cover based on the binary image; S5. Calculation of plant silhouette cover: Import the photographs of the silhouette area of ​​the sample plot plants into the digital image processing software in the mobile phone, and obtain the normalized vegetation index map and the classification thresholds of the normalized vegetation index of plants and non-plants after processing; the APP for calculating the vertical projection cover and silhouette cover of plants classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, and calculates the plant silhouette cover based on this.

8. The method for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 7, characterized in that the sample The average height of plants in a square is measured by measuring the heights of no less than 10 plants in the sample square, and calculating the average height of all measured plants as the average height of the plants.

9. The method for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 7, characterized in that: The specific processing method of step S4 is: first import the vertical projection photo of the plant taken by the camera into the digital image processing software in the mobile phone, select NDVI to calculate and obtain the normalized vegetation index map; import the normalized vegetation index map and the vertical projection photo of the plant into the ArcGIS software for superposition display, when the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the normalized vegetation index of plants and non-plants; input the determined classification threshold into the APP for calculating the vertical projection cover and silhouette cover of the plant, and the APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which the plant pixels are assigned a value of 1 and the non-plant pixels are assigned a value of 0; enter the plant vertical projection cover calculation interface in the APP program, and calculate the plant vertical projection area according to the binary image S v : S v = n×A in, n is the number of plant pixels in the sample plot; A is the pixel size; Then calculate the vertical projection coverage of the plant based on the vertical projection area of ​​the plant F v : F v =（ S v ÷ W ）×100% in, W is the area of ​​the sample plot.

10. The method for measuring vertical projection coverage and silhouette coverage of herbaceous plants according to claim 7, characterized in that: The specific method of step S5 is: first import the sample plot plant silhouette area photo taken by the camera into the digital image processing software in the mobile phone, select NDVI to calculate and obtain the normalized vegetation index map; import the normalized vegetation index map and the sample plot plant silhouette area photo into the ArcGIS software for superposition display, when the transparent display can display plant pixels but not non-plant pixels, the classification value at this time is the classification threshold of the plant and non-plant normalized vegetation index; input the determined classification threshold into the APP for calculating the vertical projection cover and silhouette cover of the plant, and the APP program classifies the normalized vegetation index map according to the classification threshold to obtain a binary image, in which plant pixels are assigned a value of 1 and non-plant pixels are assigned a value of 0; enter the plant silhouette cover calculation interface in the APP program, and calculate the plant silhouette area according to the binary image. S l : S l =（ m × A ）+ L in, m is the number of plant pixels; A is the pixel size; L is the distance between the partition and the background board; Then calculate the plant silhouette coverage based on the plant silhouette area λ c : λ c =（ S l ÷ W ）×100% in, W is the area of ​​the sample plot.

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