A method and device for measuring three-dimensional particle size of pebbles

Abstract

The present invention provides a method and device for measuring the three-dimensional particle size of pebbles, the method comprising: obtaining an image of the pebble; processing the image of the pebble to generate an orthophoto image and elevation information of the pebble; generating a boundary image of the pebble according to the orthophoto image and the elevation information; and measuring and generating the three-dimensional particle size of the pebble from the boundary image. The method solves the technical problem that the existing three-dimensional particle size of pebbles can only be obtained by manually measuring the three-axis dimensions, which is a heavy task and has low measurement efficiency.

Description

Technical Field

[0001] The invention relates to the field of image processing, and in particular to a method and a device for measuring three-dimensional particle size of pebbles. Background Art

[0002] Quantification and interpretation of the size and morphological characteristics of river and coastal sediments are important contents of sedimentary dynamic condition analysis and paleogeographic environment reconstruction. The morphology and size of sedimentary particles carry rich and important historical information, and therefore have long been valued by sedimentologists and have always been a key area of ​​sedimentological research. In addition, for coarse-grained sediments, the morphology and size of pebble particles are crucial to the study of pebble beach geomorphological evolution and sedimentary characteristics. The current characterization and description of the morphology (grain shape) and size (grain diameter) of pebbles are based on their triaxial dimensions as characteristic parameters, which are inseparable from the measurement of the triaxial dimensions of pebbles.

[0003] It should be noted that the existing three-dimensional particle size of pebbles often needs to be obtained through manual measurement of three-axis dimensions, which is a cumbersome task and has low measurement efficiency. Summary of the invention

[0004] The invention provides a method and device for measuring the three-dimensional particle size of pebbles, so as to solve the technical problem that the three-dimensional particle size of pebbles can only be obtained by manual measurement of three-axis dimensions, which is a cumbersome task and has low measurement efficiency.

[0005] According to a first aspect of the present invention, a method for measuring the three-dimensional particle size of pebbles is provided, the method comprising: acquiring an image of the pebble; processing the image of the pebble to generate an orthophoto image and elevation information of the pebble; generating a boundary image of the pebble based on the orthophoto image and the elevation information; and measuring and generating the three-dimensional particle size of the pebble from the boundary image.

[0006] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein measuring and generating the major axis size of the pebble from the boundary image includes: determining the two points on the boundary of the pebble with the longest distance from the boundary image; and calculating and generating the major axis size of the pebble based on the two points on the boundary of the pebble with the longest distance.

[0007] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the central axis size and the minor axis size of the pebble, wherein the central axis size of the pebble is measured and generated from the boundary image, including: determining the normal vector of the major axis of the pebble as the direction vector of the central axis of the pebble; determining the maximum projection and the minimum projection of the pebble in the boundary image according to the direction of the direction vector; and calculating the central axis size of the pebble according to the maximum projection and the minimum projection.

[0008] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein the minor axis size of the pebble is calculated from the boundary image and comprises: obtaining the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image; and generating the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble.

[0009] Furthermore, the pebbles are arranged on a flat background board, and the boundary image includes the background board, wherein obtaining the short axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble includes: expanding the boundary image to determine multiple boundary points on the background board away from the boundary of the pebbles; generating the elevation of the bottom of the pebble according to the elevations of the multiple boundary points on the background board; and generating the short axis size of the pebble according to the difference between the maximum elevation and the elevation of the bottom of the pebble.

[0010] Furthermore, the boundary image includes multiple pebbles, each pebble is marked with a serial number, wherein, after the three-dimensional particle size of the pebbles is measured from the boundary image, the method also includes: creating an association relationship between the serial number of the pebbles and the three-dimensional particle size of the pebbles; and displaying the serial number of each pebble and the three-dimensional particle size associated with the serial number of each pebble according to the association relationship.

[0011] According to the second aspect of the present invention, a device for measuring the three-dimensional particle size of pebbles is provided, and the device includes: an acquisition unit for acquiring an image of the pebble; a first generation unit for processing the image of the pebble to generate an orthophoto and elevation information of the pebble; a second generation unit for generating a boundary image of the pebble based on the orthophoto and the elevation information; and a measurement unit for measuring and generating the three-dimensional particle size of the pebble from the boundary image.

[0012] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein the measuring unit includes: a first determination module, used to determine the two points with the longest distance on the boundary of the pebble from the boundary image; a first calculation module, used to calculate and generate the major axis size of the pebble based on the two points with the longest distance on the boundary of the pebble.

[0013] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the central axis size and the minor axis size of the pebble, wherein the measuring unit includes: a second determination module, used to determine the normal vector of the major axis of the pebble as the direction vector of the central axis of the pebble; a third determination module, used to determine the maximum projection and the minimum projection of the pebble in the boundary image according to the direction of the direction vector; a second calculation module, used to calculate the central axis size of the pebble according to the maximum projection and the minimum projection.

[0014] Furthermore, the three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein the measuring unit includes: an acquisition module for acquiring the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image; a generation module for generating the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble.

[0015] The present invention provides a method and device for measuring the three-dimensional particle size of pebbles, the method comprising: obtaining an image of the pebble; processing the image of the pebble to generate an orthophoto image and elevation information of the pebble; generating a boundary image of the pebble according to the orthophoto image and the elevation information; and measuring and generating the three-dimensional particle size of the pebble from the boundary image. The method solves the technical problem that the existing three-dimensional particle size of pebbles can only be obtained by manually measuring the three-axis dimensions, which is a heavy task and has low measurement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a flow chart of a method for measuring the three-dimensional particle size of pebbles according to Embodiment 1 of the present invention;

[0018] Figure 2 is a schematic diagram of a boundary image of a pebble according to the first embodiment of the present invention;

[0019] Figure 3 is a mean absolute error distribution diagram of the pebble model of the first embodiment of the present invention; and

[0020] Figure 4 It is a schematic diagram of a device for measuring the three-dimensional particle size of pebbles according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the above and other features and advantages of the present invention more clear, the present invention is further described below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explaining to those skilled in the art and are only exemplary and not restrictive.

[0022] In the following description, many specific details are set forth to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that specific details need not be adopted to practice the present invention. In other cases, well-known steps or operations are not described in detail to avoid obscuring the present invention.

[0023] Embodiment 1

[0024] The present invention provides a method for measuring the three-dimensional particle size of pebbles, such as Figure 1 As shown, the method may include:

[0025] Step S11, obtaining an image of the pebble.

[0026] Specifically, the pebbles may be pebbles collected from rivers or coasts. The executor of the method of this scheme may be a processor of a host computer. This scheme may use a drone to fly over a pebble area and collect multiple images. The images of the pebbles are then sent to the host computer, and the processor of the host computer further processes the images of the pebbles.

[0027] It should be noted that the flight environment of the above-mentioned UAV can be sunny or cloudy, with a wind speed of less than 4m / s, and the flight parameters of the UAV can be a heading overlap rate of 80% and a lateral overlap rate of 70% (with a RTK horizontal positioning nominal accuracy of 1cm+1ppm and a vertical positioning nominal accuracy of 1.5cm+1ppm, and its plane mapping horizontal absolute nominal accuracy can reach 5cm). Under the above-mentioned flight environment and flight parameters, the photos taken by the UAV are relatively clear.

[0028] Step S13, processing the image of the pebble to generate an orthophoto and elevation information of the pebble.

[0029] Specifically, in this solution, ContextCapture or Pix4D, DJI Zhitu and other aerial survey image processing software can be used to process the image of the pebbles to generate orthophotos and elevation information of the pebbles. It should be noted here that this solution can divide multiple pebbles into three types of particle models: large, medium and small according to the average particle size, and use a simplified measurement background to arrange a large number of pebbles in an orderly manner on a nearly horizontal and flat marble slab (or wooden board), and use a drone to shoot at different flight altitudes. The above different heights can be 1m, 2m, 4m, 6m, 8m and 10m. It should also be noted that a level and an adjustable support column can be set on the above marble slab (or wooden board), and the above level and adjustable support column can be used to keep the pebbles in a horizontal posture when being photographed.

[0030] It should also be noted that this solution can correspond the orthophoto image coordinates to the real world coordinates, and the particle size measured on the orthophoto is the real size of the pebble particles.

[0031] Optionally, this solution can build a batch processing flow through the functional modules of ContextCapture aerial survey image processing software, such as aligning pictures, establishing dense point clouds, generating grids, and generating textures. The batch processing flow is then used to process the pictures taken by the drone to obtain the orthophotos and elevation information corresponding to the set rivers and coastal pebble beaches.

[0032] Step S15, generating a boundary image of the pebble according to the orthophoto and the elevation information.

[0033] Specifically, in this solution, the orthophoto and elevation information can be smoothed and filtered, and edge detected by MATLAB program to obtain the pebble boundary image. It should be noted that there can be multiple pebbles in this solution, and the pebble boundary image can include the boundary formed by multiple pebbles. Figure 2 shown.

[0034] Step S17, calculating and generating the three-dimensional particle size of the pebbles from the boundary image.

[0035] Specifically, after obtaining the boundary image, it is possible to perform calculations from the boundary image and then generate the three-dimensional particle size of the pebbles. The results of the three-dimensional particle size calculations can be used to study the dynamic geomorphology of coarse-grained beaches, such as the particle movement characteristics of pebbles under different time scales and different hydrodynamic conditions, such as the long cycle of nearly an annual period, the medium cycle of major and minor tides, and the short cycle before and after typhoons. The above-mentioned movement characteristics can then be used to analyze their changing laws, providing reliable data analysis for the study of pebble beach geomorphological evolution and coastal sedimentary characteristics.

[0036] Through the above steps, the present invention does not require manual measurement of pebbles. Based on the aerial survey drone, the orthophoto and elevation information of the pebbles are obtained through photography, the pebble boundaries are automatically identified, and the three-dimensional particle size of the pebbles is calculated. The measurement and calculation method is intelligent, simple, and efficient. The measurement results are accurate, stable, and reliable. It can be used for the rapid and precise measurement of the three-dimensional particle size of a large number of pebbles in the field. Therefore, the present invention solves the technical problem that the existing three-dimensional particle size of pebbles can only be obtained by manual measurement of the three-axis dimensions, which is arduous and has low measurement efficiency.

[0037] Optionally, the three-dimensional particle size of the pebble is the major axis size, the middle axis size, and the minor axis size of the pebble, wherein the major axis size of the pebble is calculated from the boundary image and includes:

[0038] Step S171, determining two points on the boundary of the pebble with the longest distance from each other from the boundary image.

[0039] Step S172, calculating and generating the major axis size of the pebble according to the two points on the boundary of the pebble with the longest distance.

[0040] Specifically, in this solution, in the above Figure 2 In the boundary graph of the pebbles, two points with the longest distance on the boundary of each pebble are searched one by one, and then the above-mentioned major axis size is generated according to the distance between the two points.

[0041] Optionally, the three-dimensional particle size of the pebble is the major axis size, the middle axis size, and the minor axis size of the pebble, wherein the middle axis size of the pebble is calculated from the boundary image and includes:

[0042] Step S173, determining the normal vector of the long axis of the pebble as the direction vector of the median axis of the pebble.

[0043] Step S174, determining the maximum projection and the minimum projection of the pebble in the boundary image according to the direction of the direction vector.

[0044] Step S175, calculating the central axis size of the pebble according to the maximum projection and the minimum projection.

[0045] Specifically, in this solution, the normal vector of the major axis (the direction vector of the medial axis) can be calculated, and then the projection of the boundary points of the pebbles (pebbles) in this direction can be calculated, and the difference between the maximum and minimum projections is the length of the medial axis.

[0046] Optionally, the three-dimensional particle size of the pebble is the major axis size, the middle axis size, and the minor axis size of the pebble, wherein the minor axis size of the pebble is calculated from the boundary image and includes:

[0047] Step S176, obtaining the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image.

[0048] Step S177, generating the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble.

[0049] Specifically, in this solution, the maximum elevation within the boundary of the pebble and the elevation of the bottom of the pebble can be searched in the boundary image to obtain the length of the minor axis.

[0050] Optionally, a plurality of pebbles are arranged on a flat background plate, and the boundary image includes an image of the background plate, wherein step S177 of obtaining the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble may include:

[0051] Step S1771, dilate the boundary image to determine multiple boundary points on the background plate away from the boundary of the pebbles.

[0052] Step S1772, generating the elevation of the bottom of the pebble according to the elevations of multiple boundary points on the background plate.

[0053] Step S1773, generating the minor axis size of the pebble according to the difference between the maximum elevation and the elevation of the bottom of the pebble.

[0054] Specifically, in this solution, multiple pebbles are arranged on a flat background board, and then the drone collects images of the multiple pebbles, and then the host computer obtains the above images for analysis and processing. The images collected by the drone include both images of the pebbles and images of the background board. It should be noted that the function of the above background board is to provide a flat background for the pebbles, which is not limited to flat marble boards, wooden boards, and cement boards. In this solution, the boundary of the pebbles can be expanded (2-5 pixels are sufficient) by image processing to obtain a circle of boundary points away from the boundary of the pebbles. It should be noted that the above circle of boundary points (multiple boundary points) away from the boundary of the pebbles are multiple points on the background board. This solution then averages the elevations of the multiple points on the background board to obtain the elevation of the bottom of the pebbles, and then generates the minor axis size of the pebbles based on the difference between the maximum elevation and the elevation of the bottom of the pebbles. It should also be noted that this solution can search for the corresponding elevation value in the pebble boundary image, and the largest one is the maximum elevation. Since only the upper half of the pebble can be seen from the drone, the true bottom elevation value of the pebble can only be calculated through the boundary points near the pebble (i.e., the circle of boundary points far away from the pebble boundary mentioned above). Therefore, in this solution, multiple pebbles need to be arranged on a flat background plate, and the elevation of the bottom of the pebble can be calculated by taking the average of multiple points on the flat background plate. That is, in this solution, the background plate must be flat to measure the bottom elevation of the pebble through this solution, and then calculate the size of the minor axis.

[0055] Optionally, the boundary image includes a plurality of pebbles, each of which is marked with a serial number, wherein after the three-dimensional particle size of the pebble is measured and obtained from the boundary image, the method further includes:

[0056] Step S18, creating an association relationship between the serial number of the pebble and the three-dimensional particle size of the pebble.

[0057] Step S19, displaying the serial number of each pebble and the three-dimensional particle size associated with the serial number of each pebble according to the association relationship.

[0058] Specifically, in this solution, after generating a boundary image, this solution can automatically number multiple pebbles. After measuring the three-dimensional particle size of the pebbles, this solution can create a correlation between the serial number of the pebble and the three-dimensional particle size of the pebble, and then display and export the detected pebble serial number and three-axis information. The user can intuitively see the three-dimensional particle size information of pebbles with different serial numbers.

[0059] In order to verify the effect of this solution, the present application collected the three-axis dimension tables of the pebble models of different sizes of pebbles (large, medium and small) measured by artificial time, as shown in Table 1, Table 2 and Table 3 below:

[0060] Table 1 Triaxial artificial measurement results of large particle model (unit: mm)

[0061] Serial number a b c Serial number a b c 1 171.5 111 68.5 9 156 145.5 111 2 200 92 86.5 10 139 107.5 42 3 161.5 133 73 11 206 152 150.5 4 172.5 143 103 12 152 114.5 96 5 134.5 124.5 112 13 191 147 101 6 224.5 168 118 14 183 142 66 7 144 126.5 103.5 15 163 97 100 8 168 144.5 78 16 145 129.5 79.5

[0062] Table 2 Triaxial artificial measurement results of particle model (unit: mm)

[0063]

[0064]

[0065] Table 3 Triaxial artificial measurement results of small particle model (unit: mm)

[0066]

[0067] This application averages the absolute errors of all models and all axes at each height to obtain the mean absolute error distribution of all models (Mean absolute error of all models), such as Figure 3 As shown, Figure 3 This is the average absolute error distribution diagram of all pebble models. The horizontal axis is the height of the drone shooting (Height), and the vertical axis is the absolute error value (Meanabsolute error). It can be seen from the figure that the error below 4 m is low and changes slowly; the error changes greatly in the 4m to 8m area; and the error changes fastest above 8m. In general coastal dynamic geomorphology and pebble coast sedimentary characteristics research, a measurement error within 5% is acceptable. Figure 3 The average absolute error at 10m is 5.782mm, and the corresponding 5% relative error is 115.64mm. It can be seen that the results obtained by the method of automatically measuring the pebble triaxial measurement by this scheme meet the accuracy of theoretical research. Therefore, compared with the manual three-dimensional measurement method, the measurement method provided by this application is simpler, more accurate, and more efficient, which greatly reduces the labor intensity and research cost. The scheme of this application is also suitable for the distribution measurement of pebble particle size in rivers and coasts with harsh outdoor environments, and can provide a research basis for future on-site triaxial measurement of pebbles.

[0068] Embodiment 2

[0069] like Figure 4 As shown, the present solution also provides a device for measuring the three-dimensional particle size of pebbles. The device can be set in a host computer or a server and other equipment, and can also be used to execute a method of one of the above embodiments. The device includes: an acquisition unit 40, which is used to acquire an image of the pebble; a first generation unit 42, which is used to process the image of the pebble to generate an orthophoto and elevation information of the pebble; a second generation unit 44, which is used to generate a boundary image of the pebble according to the orthophoto and the elevation information; and a measurement unit 46, which is used to measure and generate the three-dimensional particle size of the pebble from the boundary image.

[0070] Through the above-mentioned device, this solution does not require manual measurement of pebbles. Based on the aerial survey drone obtaining the orthophoto and elevation information of the pebbles through photography, the pebble boundaries are automatically identified and the three-dimensional particle size of the pebbles is calculated. The measurement and calculation method is intelligent, simple and efficient, and the measurement results are accurate, stable and reliable. It can be used for the fast and precise measurement of the three-dimensional particle size of a large number of pebbles in the field. Therefore, this solution solves the technical problem that the existing three-dimensional particle size of pebbles can only be obtained by manual measurement of the three-axis dimensions, which is arduous and has low measurement efficiency.

[0071] Optionally, the three-dimensional particle size of the pebble is the major axis size, median axis size and minor axis size of the pebble, wherein the measuring unit includes: a first determination module, used to determine the two points on the boundary of the pebble with the longest distance from the boundary image; a first calculation module, used to calculate and generate the major axis size of the pebble based on the two points on the boundary of the pebble with the longest distance.

[0072] Optionally, the three-dimensional particle size of the pebble is the major axis size, median axis size and minor axis size of the pebble, wherein the measuring unit includes: a second determination module, used to determine the normal vector of the major axis of the pebble as the direction vector of the median axis of the pebble; a third determination module, used to determine the maximum projection and the minimum projection of the pebble in the boundary image according to the direction of the direction vector; and a second calculation module, used to calculate the median axis size of the pebble based on the maximum projection and the minimum projection.

[0073] Optionally, the three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein the measuring unit includes: an acquisition module for acquiring the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image; and a generation module for generating the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble.

[0074] It should be understood that the specific features, operations and details described hereinabove about the method of the present invention may also be similarly applied to the device and system of the present invention, or, vice versa. In addition, each step of the method of the present invention described above may be performed by the corresponding parts or units of the device or system of the present invention.

[0075] It should be understood that each module / unit of the device of the present invention can be implemented in whole or in part by software, hardware, firmware or a combination thereof. Each module / unit can be embedded in the processor of the computer device in the form of hardware or firmware or independent of the processor, or can be stored in the memory of the computer device in the form of software for the processor to call to perform the operation of each module / unit. Each module / unit can be implemented as an independent component or module, or two or more modules / units can be implemented as a single component or module.

[0076] In one embodiment, a computer device is provided, which includes a memory and a processor, and the memory stores computer instructions executable by the processor, and the computer instructions instruct the processor to execute the steps of the method in the first embodiment of the present invention when executed by the processor. The computer device can be a server, a terminal, or any other electronic device with necessary computing and / or processing capabilities in a broad sense. In one embodiment, the computer device may include a processor, a memory, a network interface, a communication interface, etc. connected through a system bus. The processor of the computer device can be used to provide necessary computing, processing and / or control capabilities. The memory of the computer device may include a non-volatile storage medium and an internal memory. An operating system, a computer program, etc. may be stored in or on the non-volatile storage medium. The internal memory can provide an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface and the communication interface of the computer device can be used to connect and communicate with external devices through a network. The steps of the method of the present invention are executed by the processor.

[0077] The present invention may be implemented as a computer-readable storage medium having a computer program stored thereon, which causes the steps of the method of Embodiment 1 of the present invention to be executed when executed by a processor. In one embodiment, the computer program is distributed on a plurality of computer devices or processors coupled to a network so that the computer program is stored, accessed, and executed in a distributed manner by one or more computer devices or processors. A single method step / operation, or two or more method steps / operations, may be performed by a single computer device or processor or by two or more computer devices or processors. One or more method steps / operations may be performed by one or more computer devices or processors, and one or more other method steps / operations may be performed by one or more other computer devices or processors. One or more computer devices or processors may perform a single method step / operation, or perform two or more method steps / operations.

[0078] It will be appreciated by those skilled in the art that the method steps of the present invention may be performed by instructing related hardware such as a computer device or a processor through a computer program, and the computer program may be stored in a non-temporary computer-readable storage medium, which causes the steps of the present invention to be performed when the computer program is executed. Depending on the circumstances, any reference to memory, storage, database, or other media herein may include non-volatile and / or volatile memory. Examples of non-volatile memory include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, magnetic tape, floppy disk, magneto-optical data storage device, optical data storage device, hard disk, solid state disk, etc. Examples of volatile memory include random access memory (RAM), external cache memory, etc.

[0079] The various technical features described above can be combined arbitrarily. Although all possible combinations of these technical features are not described, any combination of these technical features should be considered to be covered by this specification as long as there is no contradiction in such combination.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the three-dimensional particle size of pebbles, characterized in that: The method comprises: Get the image of the pebble; Using ContextCapture aerial survey image processing software to process the image of the pebble to generate an orthophoto and elevation information of the pebble; Performing smoothing filtering and edge detection processing on the orthophoto and the elevation information to generate a boundary image of the pebble; Calculating and generating the three-dimensional particle size of the pebble from the boundary image; The three-dimensional particle size of the pebble is the major axis size, the median axis size and the minor axis size of the pebble, wherein the minor axis size of the pebble is calculated from the boundary image and comprises: obtaining the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image; and generating the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble; The pebbles are arranged on a flat background plate, the boundary image includes the background plate, wherein obtaining the short axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble comprises: performing an expansion operation on the boundary image to determine a plurality of boundary points on the background plate away from the boundary of the pebble; generating the elevation of the bottom of the pebble according to the elevations of the plurality of boundary points on the background plate; generating the short axis size of the pebble according to the difference between the maximum elevation and the elevation of the bottom of the pebble; The pebbles are divided into three particle models: large, medium and small according to the average particle size. The absolute errors of all models and all axes at each height are averaged to obtain the average absolute error distribution of all models; the height is the height taken by the drone.

2. The method according to claim 1, characterized in that: The three-dimensional particle size of the pebble is the major axis size, the middle axis size and the minor axis size of the pebble, wherein the major axis size of the pebble is calculated from the boundary image and generated by: Determine from the boundary image the two points on the boundary of the pebble with the longest distance; The major axis size of the pebble is calculated based on the two points on the boundary of the pebble with the longest distance.

3. The method according to claim 2, characterized in that The three-dimensional particle size of the pebble is the major axis size, the middle axis size and the minor axis size of the pebble, wherein the middle axis size of the pebble is calculated from the boundary image and generated by: Determine the normal vector of the long axis of the pebble as the direction vector of the median axis of the pebble; Determining the maximum projection and the minimum projection of the pebble in the boundary image according to the direction of the normal vector; The central axis size of the pebble is calculated according to the maximum projection and the minimum projection.

4. The method according to claim 1, characterized in that: The boundary image includes a plurality of pebbles, each of which is marked with a serial number. After the three-dimensional particle size of the pebbles is measured and obtained from the boundary image, the method further includes: Creating an association between the serial number of the pebble and the three-dimensional particle size of the pebble; The serial number of each pebble and the three-dimensional particle size associated with the serial number of each pebble are displayed according to the association relationship.

5. A device for measuring the three-dimensional particle size of pebbles, characterized in that: The device comprises: An acquisition unit, used for acquiring an image of the pebble; A first generating unit is used to process the image of the pebble using ContextCapture aerial survey image processing software to generate an orthophoto and elevation information of the pebble; A second generating unit, used for generating a boundary image of the pebble according to the orthophoto and the elevation information; A calculation unit, used for calculating and generating a three-dimensional particle size of the pebble from the boundary image; The three-dimensional particle size of the pebble is the major axis size, the middle axis size and the minor axis size of the pebble, wherein the measuring unit comprises: an acquisition module, used to acquire the maximum elevation of the pebble and the elevation of the bottom of the pebble from the boundary image; a generation module, used to generate the minor axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble; The pebbles are arranged on a flat background plate, the boundary image includes the background plate, wherein obtaining the short axis size of the pebble according to the maximum elevation and the elevation of the bottom of the pebble comprises: performing an expansion operation on the boundary image to determine a plurality of boundary points on the background plate away from the boundary of the pebble; generating the elevation of the bottom of the pebble according to the elevations of the plurality of boundary points on the background plate; generating the short axis size of the pebble according to the difference between the maximum elevation and the elevation of the bottom of the pebble; The measuring unit is also used to divide the pebbles into three particle models of large, medium and small according to the average particle size, and average the absolute errors of all models and all axes at each height to obtain the average absolute error distribution of all models.

6. The device according to claim 5, characterized in that The three-dimensional particle size of the pebble is the major axis size, the middle axis size and the minor axis size of the pebble, wherein the measuring unit includes: A first determination module is used to determine two points on the boundary of the pebble with the longest distance from each other from the boundary image; The first calculation module is used to calculate and generate the major axis size of the pebble according to the two points on the boundary of the pebble with the longest distance.

7. The device according to claim 6, characterized in that The three-dimensional particle size of the pebble is the major axis size, the middle axis size and the minor axis size of the pebble, wherein the measuring unit includes: A second determination module is used to determine the normal vector of the long axis of the pebble as the direction vector of the central axis of the pebble; A third determination module, configured to determine a maximum projection and a minimum projection of the pebble in the boundary image according to the direction of the direction vector; The second calculation module is used to calculate the central axis size of the pebble according to the maximum projection and the minimum projection.

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