A method and apparatus for calibrating a vegetation cover meter

Abstract

The present application relates to the field of botany and ecological measurement technology, and discloses a vegetation cover instrument calibration method and device, comprising: determining the position and area of the sample plot actually needed to be photographed, and taking a photo of the sample plot to obtain a sample plot photo; preprocessing the sample plot photo to obtain a processed photo; selecting several main vegetation colors in the processed photo as vegetation pixel colors, and selecting several main soil colors as soil pixel colors; setting a display screen; filling the display screen based on the selected vegetation pixel colors and soil pixel colors to form a training combination of the current color vegetation area ratio; comparing the similarity between the standardized vegetation map of the current color vegetation area ratio and the training combination to obtain a difference value; and calibrating the vegetation cover instrument based on the difference value. The present application can solve the problems of the existing vegetation cover instrument, such as the lack of measurement standards, large data deviation, and strong subjectivity of measurement results.

Description

Technical Field

[0001] This invention relates to the field of botanical and ecological measurement technology, and in particular to a method and apparatus for calibrating a vegetation cover meter. Background Technology

[0002] Vegetation cover is a crucial indicator for measuring ecosystem health and soil erosion, and its changes are significant for ecological protection, rational resource development, land use optimization, and sustainable development. Traditional methods for measuring vegetation cover are relatively crude, often relying on visual estimation or simple image segmentation techniques, which are highly subjective and uncertain. With advancements in measurement technology, various types of vegetation cover meters have emerged on the market, primarily employing image analysis algorithms for quantitative vegetation assessment. However, the lack of unified production standards and calibration methods for existing vegetation cover instruments leads to significant discrepancies in measurement results between different brands and models. Particularly in the field of soil and water conservation, the consistency and accuracy of vegetation cover monitoring data are difficult to control effectively, negatively impacting ecological research and governance decisions.

[0003] Therefore, developing a standardized calibration method for different vegetation cover meters can not only eliminate data deviations between different instruments, but also provide the industry with scientific measurement basis and promote the standardization and refinement of vegetation cover measurement work. Summary of the Invention

[0004] The purpose of this invention is to overcome one or more of the above-mentioned existing technical problems and provide a method for calibrating a vegetation cover meter.

[0005] To achieve the above objectives, the present invention provides a vegetation cover meter calibration method, comprising:

[0006] Determine the location and area of ​​the sample plots that actually need to be photographed, and take photos of the sample plots to obtain sample plot photos;

[0007] Preprocessing of sample plot photos yields processed photos;

[0008] Select the main vegetation colors in the processed photo as vegetation pixel colors, and the main soil colors as soil pixel colors.

[0009] Set up a display screen and fill it with the selected vegetation pixel color and soil pixel color to form a training combination of the current color vegetation area ratio. In the training combination, the coverage of the foreground color to the background color in the display screen is different.

[0010] A standardized vegetation map showing the current proportion of colored vegetation areas is obtained and compared with the training combination to obtain the difference. The vegetation cover meter is then calibrated based on the difference.

[0011] According to one aspect of the present invention, the method for obtaining the processed photograph is as follows:

[0012] Normalize the sample plot photos to obtain image data based on RGB space;

[0013] The image data is filtered for feature pixel rows, the image data is converted to grayscale, and the grayscale image data is binarized to initially segment the pixels into two categories: vegetation and soil.

[0014] Count the number of green plant pixels in each row of the grayscale image data, select the appropriate pixel row with the largest proportion of green plant pixels but not reaching 100%, find the first pixel in the pixel row from left to right, and transfer the R channel data, G channel data or B channel data of the first pixel to the right boundary of the green leaves in that row.

[0015] Starting from the beginning of the intercepted channel data, the data is divided into two groups as the dividing point. If the values ​​at the dividing point are all greater than the first group and less than the second group, then this point is selected as the threshold.

[0016] A mask image is generated from the image data using a defined threshold. The mask image is then converted to RGB format along with the sample plot photos to complete the segmentation of vegetation and soil.

[0017] According to one aspect of the present invention, the method for forming the training combination of the current color vegetation region proportions is as follows:

[0018] Set up a display screen, divide the display screen into two or more even numbers of regions with the same shape and area, and divide the regions into two groups of equal number;

[0019] Randomly assign the selected vegetation pixel color to each area in the first group, and randomly assign the selected soil pixel color to each area in the second group;

[0020] Randomly select one area from the first group as the foreground color of the display screen, and select one area from the second group as the background color of the display screen to form a training combination of the current color vegetation area ratio.

[0021] According to one aspect of the present invention, a method for obtaining a standardized vegetation map of the current color vegetation area proportion is as follows:

[0022] Generate a height map with a resolution of a×a, and take the middle height h0 in the height map according to the vegetation area ratio n input by the user.

[0023] Compare the number of pixels with a height greater than the median height, k0 / (a×a), with n. If the number is greater than n, then take the values ​​from h0 to h. max The middle height h1 is used to determine the number of pixels greater than h1, k1 / (a×a), which is compared with n.

[0024] Otherwise take h min Compare the number of pixels with a height greater than h2 in h0, k2 / (a×a), with n;

[0025] Repeat the above process to calculate the positions of pixels that match the vegetation area proportions. Add the vegetation area color to these positions and the non-vegetation area color to the other positions to obtain a standardized vegetation map of the current color vegetation area proportions.

[0026] According to one aspect of the present invention, a cluster analysis method is used to screen vegetation color and soil color.

[0027] According to one aspect of the present invention, at least two main vegetation colors and at least two main soil colors are selected.

[0028] To achieve the above objectives, the present invention provides a vegetation cover meter calibration device, comprising:

[0029] Display screen;

[0030] A sliding rail perpendicular to the direction of the display screen is installed directly below the display screen.

[0031] A slide block is installed on the slide rail, and the slide block can slide back and forth along the slide rail;

[0032] A fixed bracket is set above the slide block, and the vegetation cover meter to be calibrated is set on the fixed bracket, with the center of the lens of the vegetation cover meter facing the center of the display screen.

[0033] Calibrate the parameters of the vegetation cover meter and adjust the position of the slide block on the slide rail according to the focal length of the vegetation cover meter.

[0034] According to one aspect of the invention, a horizontally rotating lead screw is provided on the slide rail;

[0035] Install a handwheel at the end of the lead screw;

[0036] The lead screw is threadedly connected to the slide block. When the handwheel is rotated to drive the lead screw to rotate, the sliding control of the slide block is realized, and the distance between the vegetation cover meter and the display screen is adjusted.

[0037] According to one aspect of the invention, the fixing bracket includes a base frame and a top frame;

[0038] The base frame is fixed on the slide block, and the top frame is set on the vegetation cover meter;

[0039] The base frame and the top frame are rotatably connected, and a bolt is installed at the bottom of the top frame, which is located below the rotational position of both.

[0040] The base frame is provided with an arc-shaped slot for the bolts to slide through, and the base frame 31 and the top frame are fixed when the bolts are tightened, thereby enabling the adjustment of the tilt angle of the vegetation cover meter.

[0041] According to one aspect of the invention, it also includes a level, which is respectively disposed on the slide, the slide rail and the display screen.

[0042] Based on this, the beneficial effects of the present invention are as follows: the present invention can simulate different vegetation cover conditions, achieve accurate calibration of various vegetation cover meters, and eliminate measurement differences between instruments of different brands and models. This method not only improves the accuracy and consistency of vegetation cover meter measurement results, but also provides reliable data for vegetation cover monitoring in soil and water conservation, ecological protection, and resource development, and helps to promote the standardization, scientification, and refinement of measurement work in this field. Attached Figure Description

[0043] Figure 1 This is a flowchart illustrating a vegetation cover meter calibration method according to an exemplary embodiment;

[0044] Figure 2 This is a schematic diagram of a vegetation cover meter calibration device according to an exemplary embodiment;

[0045] Figure 3 This is a schematic diagram of a fixed bracket for a vegetation cover meter calibration device according to an exemplary embodiment.

[0046] Reference numerals in the attached diagram: 1. Slide rail; 2. Slide block; 3. Fixed bracket; 31. Base frame; 32. Top frame; 33. Bolt; 34. Strip hole; 4. Lead screw; 5. Handwheel; 6. Level. Detailed Implementation

[0047] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0048] As used herein, the term “comprising” and its variations are to be interpreted as open-ended terms meaning “including but not limited to”. The term “based on” is to be interpreted as “at least partially based on”, and the terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment”.

[0049] According to one embodiment of the present invention, Figure 1 This is a flowchart illustrating a vegetation cover meter calibration method according to an exemplary embodiment, such as... Figure 1 As shown, to achieve the above objective, the present invention provides a vegetation cover meter calibration method, comprising:

[0050] Determine the location and area of ​​the sample plots that actually need to be photographed, and take photos of the sample plots to obtain sample plot photos;

[0051] Preprocessing of sample plot photos yields processed photos;

[0052] Select the main vegetation colors in the processed photo as vegetation pixel colors, and the main soil colors as soil pixel colors.

[0053] Set up a display screen and fill it with the selected vegetation pixel color and soil pixel color to form a training combination of the current color vegetation area ratio. In the training combination, the coverage of the foreground color to the background color in the display screen is different.

[0054] A standardized vegetation map showing the current proportion of colored vegetation areas is obtained and compared with the training combination to obtain the difference. The vegetation cover meter is then calibrated based on the difference.

[0055] According to one embodiment of the present invention, the method for obtaining the processed photograph is as follows:

[0056] Normalize the sample plot photos to obtain image data based on RGB space;

[0057] The image data is filtered for feature pixel rows, the image data is converted to grayscale, and the grayscale image data is binarized to initially segment the pixels into two categories: vegetation and soil.

[0058] Count the number of green plant pixels in each row of the grayscale image data, select the appropriate pixel row with the largest proportion of green plant pixels but not reaching 100%, find the first pixel in the pixel row from left to right, and transfer the R channel data, G channel data or B channel data of the first pixel to the right boundary of the green leaves in that row.

[0059] Starting from the beginning of the intercepted channel data, the data is divided into two groups as the dividing point. If the values ​​at the dividing point are all greater than the first group and less than the second group, then this point is selected as the threshold.

[0060] A mask image is generated from the image data using a defined threshold. The mask image is then converted to RGB format along with the sample plot photos to complete the segmentation of vegetation and soil.

[0061] According to one embodiment of the present invention, the method for forming a training combination of the current color vegetation region proportion is as follows:

[0062] Set up a display screen, divide the display screen into two or more even numbers of regions with the same shape and area, and divide the regions into two groups of equal number;

[0063] Randomly assign the selected vegetation pixel color to each area in the first group, and randomly assign the selected soil pixel color to each area in the second group;

[0064] Randomly select one area from the first group as the foreground color of the display screen, and select one area from the second group as the background color of the display screen to form a training combination of the current color vegetation area ratio.

[0065] According to one embodiment of the present invention, the method for obtaining a standardized vegetation map of the current color vegetation area proportion is as follows:

[0066] Generate a height map with a resolution of a×a, and take the middle height h0 in the height map according to the vegetation area ratio n input by the user.

[0067] Compare the number of pixels with a height greater than the median height, k0 / (a×a), with n. If the number is greater than n, then take the values ​​from h0 to h. max The middle height h1 is used to determine the number of pixels greater than h1, k1 / (a×a), which is compared with n.

[0068] Otherwise take h min Compare the number of pixels with a height greater than h2 in h0, k2 / (a×a), with n;

[0069] Repeat the above process to calculate the positions of pixels that match the vegetation area proportions. Add the vegetation area color to these positions and the non-vegetation area color to the other positions to obtain a standardized vegetation map of the current color vegetation area proportions.

[0070] According to one embodiment of the present invention, a cluster analysis method is used to screen vegetation color and soil color.

[0071] According to one embodiment of the present invention, at least two main vegetation colors and at least two main soil colors are selected.

[0072] According to one embodiment of the present invention, the sample plot photos are taken manually, by drone, or by satellite aerial photography.

[0073] According to one embodiment of the present invention, an image dataset of different vegetation and soil is established, and the cluster centers and boundaries of the different vegetation and soil image datasets are determined. The average RGB color values ​​in the different vegetation and soil image datasets are taken to obtain the cluster centers. The difference between the RGB color values ​​in the different vegetation and soil image datasets and the cluster centers is obtained to obtain a difference matrix. The cluster boundaries are determined based on the cluster centers according to a preset threshold factor, wherein the threshold factor ranges from 0.9 to 1.1.

[0074] Based on the cluster centers and boundaries of different vegetation and soil image datasets, RGB color clustering analysis is performed on the segmented RGB images of vegetation and soil. The minimum distance between the RGB color values ​​of each pixel in the RGB images of vegetation and soil and the elements in the boundaries of different vegetation and soil image datasets is calculated to obtain the minimum distance set.

[0075] Determine the pixel in the RGB image of the segmented vegetation and soil that is closest to the element in the cluster boundary corresponding to the minimum value in the minimum distance set, and determine whether its modulus is less than a threshold. If it is less than the threshold, the type of vegetation and soil can be determined.

[0076] Pixels are calculated based on the known vegetation and soil types. The color of the vegetation type with an area greater than a preset threshold is selected as the vegetation pixel color, and the color of the soil type with an area greater than a preset threshold is selected as the soil pixel color. If the area is not greater than the preset threshold, the color is discarded.

[0077] According to one embodiment of the present invention, the display screen is divided into four identical rectangular regions, resulting in a first region, a second region, a third region, and a fourth region. The display screen is divided into four identical regions, and equal amounts of vegetation pixel colors or soil pixel colors with an area greater than a preset threshold are randomly selected. Ideally, there are two vegetation pixel colors or two soil pixel colors. The selected content is the pixel color with the largest area. The selected vegetation pixel colors are randomly assigned to the first or second region, and the selected soil pixel colors are randomly assigned to the third or fourth region. One region, i.e., the first or second region, is selected as the foreground color of the display screen, and one region, i.e., the third or fourth region, is selected as the background color of the display screen. Therefore, given a fixed pixel color, there are four randomly selected training sets. If three vegetation pixel colors and two soil pixel colors are available, then there are six randomly selected training sets.

[0078] According to one embodiment of the present invention, the coverage of the foreground color to the background color of the display screen is adjusted to one of the values ​​between 0 and 100%, and this value is not limited to an integer. The resolution of the display screen can be adjusted, and during calibration, the resolution of the display screen is consistent with the resolution of the vegetation cover meter. Therefore, this application is not limited to a single type of vegetation cover meter.

[0079] Furthermore, to achieve the aforementioned objectives, this invention also provides a vegetation cover meter calibration device. Figure 2 This is a schematic diagram of a vegetation cover meter calibration device according to an exemplary embodiment. Figure 3 This is a schematic diagram of a fixing bracket for a vegetation cover meter calibration device according to an exemplary embodiment, as shown below. Figure 2 and Figure 3As shown, a vegetation cover meter calibration device of the present invention includes:

[0080] Below the display screen, directly opposite the display screen, a slide rail 1 perpendicular to the direction of the display screen is set. A slide block 2 is set on the slide rail 1, and the slide block 2 can slide back and forth along the slide rail 1. A fixed bracket 3 is set above the slide block 2. The vegetation cover meter to be calibrated is set on the fixed bracket 3, and the center of the lens of the vegetation cover meter is opposite to the center of the display screen.

[0081] A horizontally rotating lead screw 4 is set on the slide rail 1, and a handwheel 5 is installed at the tail end of the lead screw 4. The lead screw 4 is threadedly connected to the slide block 2. When the handwheel 5 is rotated to drive the lead screw 4 to rotate, the sliding control of the slide block 2 is realized, and the distance between the vegetation cover meter and the display screen is adjusted.

[0082] The fixed support 3 includes a base frame 31 and a top frame 32. The base frame 31 is fixed on the slide 2, and the top frame 32 is set on the vegetation cover meter. The base frame 31 and the top frame 32 are rotatably connected. A bolt 33 is provided at the bottom of the top frame 32. The bolt 33 is located below the rotation position of the two. The base frame 31 is provided with an arc-shaped slot 34 for the bolt 33 to slide. When the bolt 33 is tightened, the base frame 31 and the top frame 32 are fixed, thereby realizing the adjustment of the tilt angle of the vegetation cover meter to meet different usage needs.

[0083] Calibrate the parameters of the vegetation cover meter and adjust the position of the slide block 2 on the slide rail 1 according to the focal length of the vegetation cover meter.

[0084] The level 6 is installed on the slide 2, the slide rail 1 and the display screen, so that the entire device is at the same level.

[0085] Those skilled in the art will recognize that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0086] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and equipment can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0087] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0088] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of the embodiments of the present invention, depending on actual needs.

[0089] In addition, the functional modules in the embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0090] If the aforementioned functions are implemented as software functional modules 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, essentially, or the part that contributes to the prior art, or a portion 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 energy-saving signal transmission / reception methods of 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, ROM, RAM, magnetic disks, or optical disks.

[0091] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

[0092] It should be understood that the sequence number of each step in the invention and embodiments of the present invention does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A method for calibrating a vegetation cover meter, characterized in that, The method comprises the following steps: determining the position and area of the sample plot actually needed to be photographed, and taking a photo of the sample plot to obtain a sample plot photo; preprocessing the sample plot photo to obtain a processed photo; selecting several main vegetation colors in the processed photo as vegetation pixel colors and several main soil colors as soil pixel colors; setting a display screen, filling the display screen based on the selected vegetation pixel colors and soil pixel colors, and forming a training combination of the current color vegetation area ratio, wherein the coverage of the foreground color to the background color in the display screen is different in the training combination; the method for forming the training combination of the current color vegetation area ratio comprises the following steps: dividing the display screen into an even number of regions with the same shape and area, and dividing the regions into two groups with equal number; randomly distributing the selected vegetation pixel colors in the regions in the first group and the selected soil pixel colors in the regions in the second group; randomly selecting a region in the first group as the foreground color of the display screen and a region in the second group as the background color of the display screen to form the training combination of the current color vegetation area ratio; comparing the standardized vegetation map of the current color vegetation area ratio with the training combination to obtain a difference value, and calibrating the vegetation cover instrument based on the difference value; the method for obtaining the standardized vegetation map of the current color vegetation area ratio comprises the following steps: generating a height map with a resolution of a x a, and taking the middle height h0 in the height map according to the vegetation area ratio n input by a user; The number k0 / (a x a) of pixel points greater than the middle height h0 is compared with n, and if greater than n, the middle height h1 in h0 to h max is taken, and the number k1 / (a x a) of pixel points greater than h1 is compared with n. Otherwise take h min With the intermediate height h2 in h0, the number k2 / (a x a) of pixel points greater than h2 is compared with n. repeating the above process to calculate the positions of the pixel points meeting the vegetation area ratio, adding the vegetation area color to these positions and adding the non-vegetation area color to other positions to obtain the standardized vegetation map of the current color vegetation area ratio.

2. The method of calibrating a vegetation cover meter of claim 1, wherein, the method for obtaining the processed photo comprises the following steps: performing normalization processing on the sample plot photo to obtain image data based on the RGB space; filtering feature pixel rows from the image data, performing grayscale processing on the image data, performing binaryzation on the grayscale image data, and initially segmenting vegetation and soil pixels; counting the number of green pixel rows in the grayscale image data, selecting a suitable pixel row with the largest green pixel number and less than 100%, and finding the first pixel point from left to right in the pixel row, taking the R channel data, G channel data or B channel data from the first pixel point to the right boundary of the green leaf in the row as the green pixel number in the row; starting from the beginning of the intercepted channel data as a dividing point, dividing the data into two groups, and selecting the point as a threshold value if the values at the point are all greater than the first group and less than the second group; forming a mask map from the determined threshold value, converting the mask map and the sample plot photo to the RGB format, and completing the segmentation of vegetation and soil.

3. A method of calibrating a vegetation cover meter as claimed in claim 2, wherein, The method adopts a clustering analysis method to filter vegetation colors and soil colors.

4. The method of calibrating a vegetation cover meter of claim 3, wherein, The number of selected main vegetation colors is not less than 2, and the number of selected main soil colors is not less than 2.

5. A vegetation cover instrument calibration device applied to the vegetation cover instrument calibration method according to any one of claims 1-4, characterized in that the device comprises: a display screen; a slide rail perpendicular to the direction of the display screen arranged below the display screen and opposite to the display screen. The sliding seat is arranged on the slide rail and can slide forward and backward along the slide rail; A fixed support is arranged above the sliding seat, and the vegetation cover instrument to be calibrated is arranged on the fixed support, and the center of the lens of the vegetation cover instrument is opposite to the center of the display screen; The parameters of the vegetation cover instrument are calibrated, and the position of the sliding seat on the slide rail is adjusted according to the focal length of the vegetation cover instrument.

6. The vegetation cover instrument calibration device according to claim 5, wherein, A horizontally rotating lead screw is arranged on the slide rail; A hand wheel is installed at the tail end of the lead screw; The lead screw is threadedly connected with the sliding seat, and when the lead screw is rotated by rotating the hand wheel, the sliding seat is controlled to slide, and the distance between the vegetation cover instrument and the display screen is adjusted.

7. The vegetation cover instrument calibration device according to claim 6, wherein, The fixed support comprises a bottom frame and a top frame; The bottom frame is fixed on the sliding seat, and the top frame is arranged on the vegetation cover instrument; The bottom frame and the top frame are rotationally connected, the bottom end of the top frame is provided with a bolt, and the bolt is located below the rotation position of the two; An arc-shaped strip hole is arranged on the bottom frame for the sliding of the bolt, and when the bolt is tightened, the bottom frame and the top frame are fixed, so that the inclination angle of the vegetation cover instrument is adjusted.

8. A calibration device for a vegetation cover meter according to claim 7, wherein A level is further arranged on the sliding seat, the slide rail and the display screen.

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