A monitoring method for the sand fixation function of sand barriers based on drones
The drone-based method for monitoring sand barrier effectiveness addresses inefficiencies in traditional methods by providing accurate, efficient, and comprehensive assessment of sand dune changes, enhancing monitoring precision and reducing costs.
Patent Information
- Application Number
- CN202210357867.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-04-06
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2042-04-06
AI Technical Summary
The prior art has problems in the monitoring of sand barrier sand fixing function, such as large quantitative evaluation errors, time-consuming and labor-intensive, and can only monitor single indicators and cannot monitor the three-dimensional morphological changes of sand dunes.
The drone is used to obtain the sand barrier control area images, generate digital orthophotograms and digital surface models through air three calculations, draw topographic maps with digital elevation models, calculate the air accumulation and wind erosion amount, and realize large-scale monitoring.
It improves monitoring efficiency, reduces costs, and accurately judges the sand barrier sand fixing function through dune ridge lines, slope foot lines and elevation changes data, improving monitoring content and accuracy.
Smart Images
Figure CN114897776B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of wind prevention and sand fixation, and particularly relates to a monitoring method for the sand fixation function of sand barriers based on unmanned aerial vehicles (UAVs). Background Art
[0002] Currently, the traditional "tag method" is still commonly used to monitor the sand fixation function of sand barriers. With the emergence of monitoring instruments, the "sand accumulation instrument method" has also emerged. These methods are fixed-point measurement methods that set up stakes and sand accumulation instruments on the ground in the sand barrier establishment area, i.e., the sand barrier control area, and finally estimate the sand fixation effect (sand fixation function) of the living sand barrier based on the changes in the sand surface activities at the positioning points. Currently, there is no technical means to use aerial UAVs to conduct large-scale monitoring of the sand fixation function of sand barriers.
[0003] The traditional monitoring methods for the sand fixation function of sand barriers have the following deficiencies:
[0004] First, the traditional monitoring methods estimate the sand fixation effect (sand fixation function) of the living sand barrier based on the changes in the sand surface activities at the positioning points, which will undoubtedly bring certain errors to the quantitative evaluation of the sand fixation effect of the overall sand barrier (or a complete sand barrier establishment area). Moreover, the flow of sand grains driven by the wind is not uniform in a certain area. Therefore, the traditional point-to-area monitoring method has the serious deficiency of overgeneralization.
[0005] Second, when conducting large-scale monitoring through traditional monitoring methods, many stakes and instruments that meet the monitoring standards are required. At the same time, manual on-site layout of the stakes and instruments is needed, and measurements and sampling records are required from time to time. It can be seen that the traditional monitoring methods are time-consuming, laborious, and costly.
[0006] Third, in the traditional monitoring methods, the tag method can only obtain the height changes of the sand surface; the sand accumulation instrument method can only obtain the volume of sand grain movement. That is to say, the traditional methods directly monitor only single indicators. And through the traditional monitoring methods, the intuitive changes in the three-dimensional shape of the sand dunes cannot be monitored.
[0007] Therefore, how to quickly and effectively monitor the sand fixation function of sand barriers, while improving the monitoring efficiency and reducing the monitoring cost, has become the key issue in current research. Summary of the Invention
[0008] In view of the above problems, the present invention provides a monitoring method for the sand fixation function of sand barriers based on UAVs, which can at least solve some of the above technical problems. Through this method, the sand fixation function of sand barriers can be quickly and effectively monitored, while improving the monitoring efficiency and reducing the monitoring cost.
[0009] An embodiment of the present invention provides a monitoring method for the sand fixation function of sand barriers based on UAVs, including:
[0010] S1. Using a UAV to obtain images of the target sand barrier control area;
[0011] S2. Perform aerial triangulation on the image of the target sand barrier control area to obtain the digital orthophoto map DOM and digital surface model map DSM of the target sand barrier control area; and process the digital surface model map DSM to obtain the digital elevation model map DEM of the target sand barrier control area.
[0012] S3. Draw the topographic map of the target sand barrier control area according to the digital elevation model map DEM.
[0013] S4. Calculate the wind-deposited amount and wind-erosion amount of the target sand barrier control area according to the digital orthophoto map DOM, digital elevation model map DEM and topographic map.
[0014] Further, the S1 specifically includes:
[0015] Layout image control points and inspection points: Set one image control point at each of the four corners and the center of the target sand barrier control area, and evenly layout multiple inspection points within the UAV flight area.
[0016] Set the flight parameters of the UAV: The yaw angle of the UAV is not greater than 15°; the curvature of the UAV flight path is not greater than 3%; the side overlap of the UAV flight path is 70%; the forward overlap of the UAV aerial photographs is 80%; the UAV flight speed is 7.9 m / s; the UAV flight altitude is 100 m; the ratio of the length to the width of the aerial image of the target sand barrier control area is 4:3.
[0017] Further, an RTK instrument and a camera are carried on the UAV.
[0018] Further, the S2 specifically includes:
[0019] S21. Use Pix4Dmapper software to perform aerial triangulation on the images of the target sand barrier control area taken by the RTK instrument and the camera to obtain the digital orthophoto map DOM and digital surface model map DSM of the target sand barrier control area.
[0020] S22. Use PixelGrid software to perform stereo editing on the digital surface model map DSM to obtain the digital elevation model map DEM of the target sand barrier control area.
[0021] Further, the S3 specifically includes:
[0022] S31. Use the EPS 3D mapping software to load the vertical image map of the digital surface model map DSM, extract elevation points in a preset grid size by area selection; for the dune ridge line and the slope bottom line, encrypt and extract them by point selection; and export the extracted elevation points to an elevation point data file with the extension.dat.
[0023] S32. Process the elevation point data file through the CASS software. Specifically, after removing the distorted points, generate contour lines based on a preset contour interval, and smooth the contour lines.
[0024] S33. Based on the contour lines after the smoothing process in S32, use the EPS software to draw the scenery within the target sand barrier control area onto the map with corresponding symbols to form the topographic map of the target sand barrier control area.
[0025] Furthermore, the S4 specifically includes:
[0026] Calculate the horizontal displacement data of the dune ridge line and the horizontal displacement change data of the slope toe line in the target sand barrier control area according to the topographic map.
[0027] Calculate the dune elevation change data in the target sand barrier control area according to the digital orthophoto map DOM and the topographic map.
[0028] Calculate the dune moving earthwork volume change data in the target sand barrier control area according to the digital elevation model map DEM.
[0029] Furthermore, the calculation of the horizontal displacement of the dune ridge line and the horizontal displacement of the slope toe line in the target sand barrier control area according to the topographic map specifically includes:
[0030] In the EPS 3D mapping software, load the historical digital surface model map DSM and the current stage digital surface model map DSM respectively.
[0031] Adopt point selection to collect the topographic feature points of the dune ridge line and the slope toe line in the historical digital surface model map DSM and the current stage digital surface model map DSM respectively, and export the topographic feature points of the dune ridge line and the slope toe line as a dat data file.
[0032] Import the dat file into the CASS software, and draw the dune ridge line and the slope toe line in the historical stage and the current stage respectively.
[0033] Subtract the data of the dune ridge line and the slope toe line in the historical stage from the data of the dune ridge line and the slope toe line in the current stage. The positive value obtained belongs to the wind erosion amount; the negative value obtained belongs to the wind accumulation amount.
[0034] Further, calculating the dune elevation change data of the target sand barrier control area based on the digital orthophoto map DOM and topographic map specifically includes:
[0035] Analyze the dune distribution patterns in the digital orthophoto map DOM of the target sand barrier control area in the historical stage and the dune distribution patterns in the digital orthophoto map DOM of the target sand barrier control area in the current stage through ArcGIS; and respectively draw the elevation change profile lines in the historical stage and the current stage along the key dune ridge lines.
[0036] Overlay the elevation change profile lines with the topographic map of the corresponding stage, and use CASS to respectively draw the dune ridge line elevation change map in the historical stage and the dune ridge line elevation change map in the current stage.
[0037] Subtract the dune ridge line elevation change data in the historical stage from the dune ridge line elevation change data in the current stage. The positive value obtained belongs to the wind accumulation amount; the negative value obtained belongs to the wind erosion amount.
[0038] Further, calculating the dune moving earthwork volume change data of the target sand barrier control area based on the digital elevation model map DEM specifically includes:
[0039] Generate the digital terrain model DTM in the historical stage and the digital terrain model DTM in the current stage respectively according to the digital elevation model map DEM in the historical stage and the current stage.
[0040] Obtain the dune moving earthwork volume data in the historical stage and the dune moving earthwork volume data in the current stage from the digital terrain model DTM in the historical stage and the digital terrain model DTM in the current stage respectively through CASS software.
[0041] Subtract the dune moving earthwork volume data in the historical stage from the dune moving earthwork volume data in the current stage. The positive value obtained belongs to the wind accumulation amount; the negative value obtained belongs to the wind erosion amount.
[0042] Compared with the prior art, a method for monitoring the sand fixation function of a sand barrier based on an unmanned aerial vehicle recorded in the present invention has the following beneficial effects:
[0043] Monitor through an unmanned aerial vehicle, realize large-scale area monitoring, improve the monitoring efficiency, and reduce the monitoring cost at the same time.
[0044] Judge the sand fixation function of the sand barrier by reflecting the wind erosion amount and wind accumulation amount through the horizontal displacement of the dune ridge line, the dune elevation and the volume (earthwork) change data, which greatly improves the monitoring content and accuracy.
[0045] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention may be realized and attained by the structure particularly pointed out in the written description, claims, as well as the drawings.
[0046] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings
[0047] The drawings are used to provide a further understanding of the present invention, and constitute a part of the description. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:
[0048] Figure 1 It is a flowchart of the method for monitoring the sand fixation function of sand barriers based on unmanned aerial vehicles provided by the embodiment of the present invention.
[0049] Figure 2 It is a diagram showing the horizontal movement changes of the dune ridge line and the toe line in the sand barrier control area of Monitoring Sample Area 1 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0050] Figure 3 It is a diagram showing the horizontal movement changes of the dune ridge line and the toe line in the sand barrier control area of Monitoring Sample Area 2 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0051] Figure 4 It is a diagram showing the elevation change of the dunes in the sand barrier control area of Monitoring Sample Area 1 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0052] Figure 5 It is a diagram showing the elevation change of the dunes in the sand barrier control area of Monitoring Sample Area 2 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0053] Figure 6(a) is a diagram showing the historical three-dimensional changes of the dunes in the sand barrier control area of Monitoring Sample Area 1 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0054] Figure 6(b) is a diagram showing the three-dimensional changes of the dunes in the sand barrier control area of Monitoring Sample Area 1 in Mu Us Sandy Land at the current stage 2 provided by the embodiment of the present invention.
[0055] Figure 7(a) is a diagram showing the historical three-dimensional changes of the dunes in the sand barrier control area of Monitoring Sample Area 2 in Mu Us Sandy Land provided by the embodiment of the present invention.
[0056] Figure 7(b) is a diagram showing the three-dimensional changes of the dunes in the sand barrier control area of Monitoring Sample Area 2 in Mu Us Sandy Land at the current stage 2 provided by the embodiment of the present invention. Detailed Embodiments
[0057] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.
[0058] Referring to Figure 1 As shown, an embodiment of the present invention provides a method for monitoring the sand fixation function of sand barriers based on drones, specifically including the following steps:
[0059] S1. Use a drone to obtain an image of the target sand barrier control area;
[0060] S2. Perform aerial triangulation on the image of the target sand barrier control area to obtain a digital orthophoto map DOM and a digital surface model map DSM of the target sand barrier control area; and process the digital surface model map DSM to obtain a digital elevation model map DEM of the target sand barrier control area;
[0061] S3. Draw a topographic map of the target sand barrier control area according to the digital elevation model map DEM;
[0062] S4. Calculate the wind-deposited amount and wind-erosion amount of the target sand barrier control area according to the digital orthophoto map DOM, the topographic map, and the digital elevation model map DEM.
[0063] Taking the Maowusu Sand Dunes as an example, the above steps will be described in detail below.
[0064] In the above step S1, first, image control points and check points are arranged:
[0065] One image control point is arranged at each of the four corners and the center of the target sand barrier control area; 6 check points are evenly arranged within the flight area. Among them, the image control point marker is a prefabricated spray-painted cloth with a white background and a red "+" pattern, which is arranged in an open and obvious place, and the check points are temporarily sprayed with red paint on a flat and open place. The plane positions and elevations of the image control points and check points are measured twice by the CORS—RTK method, and the median of the measurement results is used. The image control point data is sorted and exported as a text format (txt) file. The coordinate system of the monitoring area adopts the 2000 National Geodetic Coordinate System, the 37th zone of the Gauss 3-degree zone, the longitude of the central meridian is 108°, and the elevation system is the 2000 National Geodetic Elevation Datum.
[0066] Secondly, the flight parameters and flight routes of the drone are set:
[0067] The flight platform is the DJI Phantom 4 RTK drone, equipped with a camera with a pixel count of 24 million. According to the scope of the monitoring area, the flight path is planned, and the roll angle of the drone is set to be no more than 15°; the curvature of the drone's flight path is no more than 3%; the side overlap of the drone's flight path is 70%; the forward overlap of the drone's aerial photographs is 80%; the drone's flight speed is 7.9 m / s; the ratio of the length to the width of the image of the target sand barrier control area is 4:3. The relative flight altitude is set to 100 m. The take-off point is set on a flat high ground with good visibility conditions in the monitoring area, which can ensure sufficient resolution of the aerial photographs and guarantee flight safety at the same time. The pixel block resolution of the aerial photograph (i.e., the minimum ground sampling distance) is 2.74 cm, and the piercing point error of the image control point is less than 2.4 cm in the plane position and less than 3 cm in elevation.
[0068] In the above step S2, the image of the target sand barrier control area obtained by the drone is processed:
[0069] The Swiss Pix4Dmapper software is used to perform aerial triangulation on the image of the target sand barrier control area, and outputs results such as the digital orthophoto map (DOM) and digital surface model (DSM) of the target sand barrier control area. Specifically: First, aerial triangulation is performed on the image of the target sand barrier control area. After the aerial triangulation is qualified, the software automatically generates dense point cloud data, generates surface texture, and then outputs the DOM (digital orthophoto map) and DSM (digital surface model). Then, the PixelGrid software is used to perform stereo editing on the obtained DSM file above (processing ground buildings, vegetation, etc. in the monitoring area) to generate a digital elevation model (DEM).
[0070] Among them, aerial triangulation operation is analytical aerial triangulation or computerized encryption. Aerial triangulation is a measurement method in stereophotogrammetry. According to a small number of field control points, control points are encrypted indoors to obtain the elevation and plane positions of the encrypted points. Its purpose is to provide absolute orientation control points for mapping areas lacking field control points. The accuracy of aerial triangulation, the mean square error of the plane position of the interior encrypted points relative to the nearby control points is less than 0.2 m, and the specified limit error for aerial surveying interior work is 1.1 m; the mean square error of the elevation of the encrypted points relative to the elevation of the nearby control points is less than 0.3 m, and the specified limit error for aerial surveying interior work is 1.2 m.
[0071] In the above step S3, first, the EPS three-dimensional mapping software is used to load the vertical image of the digital surface model map DSM generated after aerial triangulation, and elevation points are extracted in a grid of a preset size in a face selection manner. In the embodiment of the present invention, the grid size is 3 m × 3 m; for key parts such as the dune ridge line and slope bottom line, they are encrypted and extracted in a point selection manner; and the extracted elevation points are exported as an elevation point data file with the extension.dat;
[0072] Then, the elevation point data file is processed by CASS software. Specifically, after removing the distorted points, contour lines are generated based on a preset contour interval; and the contour lines are smoothed; for example, errors such as sharp corners and overlaps are corrected, especially for the contour lines in low-lying areas to make their representation more reasonable; in the embodiment of the present invention, the contour interval is set to 1m.
[0073] Finally, based on the smoothed contour lines, through EPS software, the scenery (such as roads, trees, etc.) within the target sand barrier control area is outlined in the figure with corresponding symbols to form a topographic map of the target sand barrier control area.
[0074] In this step, the mapping scale of the topographic map of the target sand barrier control area is 1:500. After the main elements of the topographic map are drawn, the whole map is decorated. The elevation points on the map surface are filtered and thinned. Considering that the subsequent drawings need to use complete contour lines, the contour lines covered by elevation annotations are not cut. After the map decoration is completed, it is printed in color with arbitrary sheet division.
[0075] In the above step S4, the dynamic changes of the sand dunes within the target sand barrier control area can be represented by the wind erosion amount and the wind accumulation amount, and the wind erosion amount and the wind accumulation amount are mainly analyzed and measured through the horizontal displacement changes of the sand dune ridge line and the toe line, the volume change of the sand dunes, and the changes in the distribution pattern of the sand dunes.
[0076] Step S4 specifically includes: calculating the horizontal displacement change data of the sand dune ridge line and the toe line of the target sand barrier control area according to the topographic map; calculating the sand dune elevation change data of the target sand barrier control area according to the digital orthophoto map DOM and the topographic map; calculating the change data of the moving earthwork volume of the sand dunes in the target sand barrier control area according to the digital elevation model map DEM.
[0077] (1) Analyze the displacement changes of the sand ridge line and the toe line:
[0078] In the EPS three-dimensional mapping software, the digital surface models (DSM) of the historical stage and the current stage are respectively loaded, and the topographic feature points of the sand dune ridge line and the toe line are respectively collected in a point selection manner to generate a dat data file of the sand dune ridge line and the toe line including the point number, x, y coordinates and elevation values.
[0079] Draw a sand dune movement change map of the sand barrier control area with a scale of 1:500. Import the generated dat data file into CASS software, and draw the sand dune ridge lines and toe lines of the two periods point by point in different colors on different layers.
[0080] Among them, the terrain feature points are the landmark points for obtaining the movement of the dune ridge line and the dune toe line. They are manually marked on the DSM map at equal distances along the ridge line and the toe line (usually the distance between feature points is 20m). The positions of the feature points in the two periods of history and the current stage must be consistent. In this way, based on the feature points, the movement changes of the ridge line and the toe line are judged.
[0081] From Figure 2 and Figure 3 It can be seen that for the displacement change status of the dune ridge line and the toe line in the historical stage and the current stage, subtract the data of the dune ridge line and the toe line in the historical stage from the data of the dune ridge line and the toe line in the current stage. The positive value obtained belongs to the wind erosion amount; the negative value obtained belongs to the wind accumulation amount. For example, the average displacement of the sand ridge line in Monitoring Area 2 is 2.79m, the maximum displacement is 6.38m, the average displacement of the toe line is 1.64m, and the maximum displacement is 2.39m; for the sand barrier afforestation monitoring area, the average displacement of the sand ridge line is 2.44m, the maximum displacement is 4.71m, the average displacement of the toe line is 2.28m, and the maximum displacement is 5.15m.
[0082] (2) Analyze the change in dune elevation:
[0083] In ArcGIS, interpret and analyze the dune distribution patterns shown in the Digital Orthophoto Map DOM in the historical stage and the current stage. Cut the elevation change profile lines of the historical stage and the current stage along the main dune ridge lines and export them in dwg format.
[0084] In CASS, overlay the generated elevation change profile lines with the topographic maps of the corresponding stages. Use the function module for drawing cross-section diagrams in CASS to draw the profile line diagrams of the historical stage and the current stage respectively and perform overlay processing. After appropriate editing, generate the dune ridge line elevation change diagram.
[0085] For Figure 4 and Figure 5 calculate the dune ridge line elevation change data. Subtract the dune ridge line elevation change data in the historical stage from the dune ridge line elevation change data in the current stage. The positive value obtained is the wind accumulation amount; the negative value obtained is the wind erosion amount. For example, the average value of the elevation change of 11 statistical samples at Point 1 in the monitoring sample area during the historical stage and the current stage is 0.358m, and the maximum value is 1.59m (decrease); the average value of the elevation change of 18 statistical samples in Monitoring Sample Area 2 is 0.861m, and the maximum value is 3.1m (decrease). Comparing the two groups of data, it can be seen that the impact on the dune height after the construction of sand barriers is relatively significant.
[0086] (3) Analyze the change in the moving earthwork volume of the dunes:
[0087] The elevation data extracted from the aerial photography materials of the historical stage and the current stage are used to generate the digital terrain models (DTMs) of the historical stage and the current stage respectively. In the CASS software, by subtracting the sand dune movement earthwork volume data of the historical stage from that of the current stage, the positive value obtained is the wind accumulation volume, and the negative value obtained is the wind erosion volume. The following Table 1 and Table 2 are obtained after statistics in the embodiments of the present invention:
[0088] Table 1: Statistical Table of Sand Dune Volume Change in the Sand Bar Control Area of Monitoring Sample Area 1
[0089]
[0090]
[0091] Table 2: Statistical Table of Volume Change in the Sand Bar Control Area of Monitoring Sample Area 2
[0092]
[0093]
[0094] As can be seen from Table 1 and Table 2 above, the total area of Monitoring Sample Area 1 is 96,029.7 ㎡ (where: the area of bare sand plots is 67,401.7 ㎡, and the area of sand bar plots is 28,628.0 ㎡); the total wind accumulation volume in the sand bar establishment area is 17,713.2 m 3 (where: the wind accumulation volume of the bare sand plot is 13,622.1 m 3 , and the wind accumulation volume of the sand bar plot is 4,091.1 m 3 ); the total wind erosion volume in the sand bar establishment area is 1,838.1 m 3 (where: the wind erosion volume of the bare sand plot is 1,589.4 m 3 , and the wind erosion volume of the sand bar plot is 248.7 m 3 ). The total area of Monitoring Sample Area 2 is 115,194.0 ㎡ (where: the total area of bare sand plots is 91,736.6 ㎡, and the total area of sand bar plots is 23,457.4 ㎡); the total wind accumulation volume of the bare sand dunes is 24,680.8 m 3 (where: the wind accumulation volume of the bare sand plot is 23,118.9 m 3 , and the wind accumulation volume of the sand bar plot is 1,561.9 m 3 ); the total wind erosion volume of the bare sand dunes is 14,696.8 m 3 (where: the wind erosion volume of the bare sand plot is 12,491.2 m 3 , and the wind erosion volume of the sand bar plot is 2,205.6 m 3 ).
[0095] (4) Three-dimensional Image Map
[0096] Load the extracted elevation data in ArcGIS or screen the contour lines in the topographic map to create a TIN (Triangulated Irregular Network) to generate a digital elevation model, i.e., DEM. Apply the classified color function, select an appropriate gradient color (green - yellow - red) in its properties, and perform color classification on the generated DEM raster map at an elevation interval of 0.5 m, so as to visually (three - dimensionally) display the change details of the dunes from high to low. The three - dimensional images of the current stage and the historical stage refer to Figure 6(a), Figure 6(b), Figure 7(a) and Figure 7(b) respectively.
[0097] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, the present invention also intends to include these changes and modifications.
Claims
1. A method for monitoring the sand fixation function of sand barriers based on unmanned aerial vehicles, characterized in that, Including: S1. Use a drone to obtain images of the target sand barrier control area; S2. Perform aerial triangulation on the images of the target sand barrier control area to obtain the digital orthophoto map DOM and digital surface model map DSM of the target sand barrier control area; and process the digital surface model map DSM to obtain the digital elevation model map DEM of the target sand barrier control area; S3. Draw a topographic map of the target sand barrier control area based on the digital elevation model map DEM; S4. Calculate the wind-blown sand accumulation and wind erosion amounts in the target sand barrier control area based on the digital orthophoto map DOM, digital elevation model map DEM, and topographic map; The specific steps of S3 include: S31. Use EPS 3D mapping software to load the vertical image map of the digital surface model map DSM, extract elevation points in a preset-sized grid by area selection; for the dune ridge line and slope bottom line, extract them densely by point selection; and export the extracted elevation points to an elevation point data file with the extension.dat; S32. Process the elevation point data file through CASS software, specifically by removing distorted points, generating contour lines based on a preset contour interval, and smoothing the contour lines; S33. Based on the smoothed contour lines in S32, use EPS software to draw the scenery in the target sand barrier control area onto the map with corresponding symbols to form the topographic map of the target sand barrier control area; The specific steps of S4 include: Calculate the horizontal displacement change data of the dune ridge line and the horizontal displacement change data of the slope toe line in the target sand barrier control area based on the topographic map; Calculate the dune elevation change data in the target sand barrier control area based on the digital orthophoto map DOM and the topographic map; Calculate the dune moving earthwork volume change data in the target sand barrier control area based on the digital elevation model map DEM.
2. The method for monitoring the sand fixation function of sand barriers based on an unmanned aerial vehicle according to claim 1, wherein The specific steps of S1 include: Layout image control points and inspection points: Set one image control point at each of the four corners and the center of the target sand barrier control area, and evenly layout multiple inspection points within the drone flight area; Set the flight parameters of the drone: The yaw angle of the drone is not greater than 15°; the course curvature of the drone is not greater than 3%; the side overlap of the drone's flight lines is 70%; the forward overlap of the drone's aerial photos is 80%; the flight speed of the drone is 7.9 m / s; the flight altitude of the drone is 100 m; the ratio of the length to the width of the aerial images of the target sand barrier control area is 4:
3.
3. The method for monitoring the sand fixation function of sand barriers based on drones according to claim 2, characterized in that, The drone carries an RTK instrument and a camera.
4. The method for monitoring the sand fixation function of sand barriers based on an unmanned aerial vehicle according to claim 3, wherein, The specific steps of S2 include: S21. Use Pix4Dmapper software to perform aerial triangulation on the images of the target sand barrier control area taken by the RTK instrument and the camera to obtain the digital orthophoto map DOM and digital surface model map DSM of the target sand barrier control area; S22. Use PixelGrid software to perform stereoscopic editing on the digital surface model map DSM to obtain the digital elevation model map DEM of the target sand barrier control area.
5. The method for monitoring the sand fixation function of sand barriers based on an unmanned aerial vehicle according to claim 1, wherein Calculating the horizontal displacement of the dune ridge line and the horizontal displacement of the toe line of the target sand barrier control area according to the topographic map specifically includes: In the EPS 3D mapping software, load the historical digital surface model map DSM and the current stage digital surface model map DSM respectively; Adopt the point selection method to collect the topographic feature points of the dune ridge line and the toe line in the historical digital surface model map DSM and the current stage digital surface model map DSM respectively, and export the topographic feature points of the dune ridge line and the toe line as a dat data file; Import the dat file into the CASS software, and draw the dune ridge line and the toe line in the historical stage and the current stage respectively; Subtract the horizontal displacement data of the dune ridge line and the toe line in the historical stage from the data of the dune ridge line and the toe line in the current stage. The positive value obtained belongs to the wind erosion amount; the negative value obtained belongs to the wind accumulation amount.
6. The method for monitoring the sand fixation function of sand barriers based on an unmanned aerial vehicle according to claim 1, wherein Calculating the dune elevation change data of the target sand barrier control area according to the digital orthophoto map DOM and the topographic map specifically includes: Analyze the dune distribution pattern in the digital orthophoto map DOM of the target sand barrier control area in the historical stage and the dune distribution pattern in the digital orthophoto map DOM of the target sand barrier control area in the current stage through ArcGIS; and respectively cut out the elevation change profile lines in the historical stage and the current stage along the key dune ridge lines; Overlay the elevation change profile line with the topographic map of the corresponding stage, and use CASS to draw the dune ridge line elevation change map in the historical stage and the dune ridge line elevation change map in the current stage respectively; Subtract the dune ridge line elevation change data in the historical stage from the dune ridge line elevation change data in the current stage. The positive value obtained belongs to the wind accumulation amount; the negative value obtained belongs to the wind erosion amount.
7. The method for monitoring the sand fixation function of sand barriers based on an unmanned aerial vehicle according to claim 1, wherein Calculating the dune moving earthwork volume change data of the target sand barrier control area according to the digital elevation model map DEM specifically includes: Generate the digital terrain model DTM in the historical stage and the current stage respectively according to the digital elevation model map DEM in the historical stage and the current stage; Obtain the dune moving earthwork volume data in the historical stage and the current stage from the digital terrain model DTM in the historical stage and the current stage respectively through the CASS software; Subtract the dune moving earthwork volume data in the historical stage from the dune moving earthwork volume data in the current stage. The positive value obtained belongs to the wind accumulation amount; the negative value obtained belongs to the wind erosion amount.