Slope top / bottom line extraction system and method
The slope top/bottom line extraction system automatically extracts the top/bottom line of the mine slope using bilinear interpolation and the OTSU algorithm, solving the problems of time-consuming inefficiency and high labor costs of traditional methods, and achieving efficient and accurate acquisition of slope top/bottom line.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-27
- Publication Date
- 2026-03-27
AI Technical Summary
Traditional methods for extracting the top/bottom of mine slopes are time-consuming, inefficient, require excessive manual labor and resources, and have poor applicability.
A slope top/bottom line extraction system is adopted, including a data preprocessing unit, a grayscale image edge extraction unit, and a slope top/bottom line extraction unit. It automatically extracts the slope top/bottom line using bilinear interpolation, bilateral filtering, and the OTSU algorithm, achieving adaptive threshold segmentation and elevation and slope information discrimination.
It improves the efficiency and accuracy of slope top/bottom line extraction, reduces manual intervention, adapts to different mining area characteristics, and meets the rapid acquisition needs of mine construction.
Smart Images
Figure CN116309284B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of ecological management and restoration of mines, and more particularly to a slope top / bottom line extraction system and method. BACKGROUND
[0002] In actual mine management, the slope top / bottom line plays a very important role, and accurate extraction of the slope top / bottom line is widely needed for calculation of stripping amount, calculation of filling and excavation, road network planning, etc. in the actual construction process.
[0003] In the ecological management and restoration process of an open-pit mine, the edge pixels are generally extracted by calculating the standard deviation and setting a threshold value, and the final data is output after a series of edge connection and thinning processing. However, the above-mentioned method for extracting the traditional pit slope top / bottom line is time-consuming and inefficient, and the labor input and consumption cost are too high. The existing method for extracting the pit slope top / bottom line has a large amount of calculation.
[0004] Currently, scholars at home and abroad have different algorithms for extracting feature lines in DEM of a three-dimensional model, such as calculating the standard deviation and setting a threshold value after data upsampling and other preprocessing according to DEM, converting DEM into a gray-scale image, starting gradient calculation to extract edge pixels, and outputting final data. However, the above-mentioned algorithm has poor universality due to different characteristics of different mining areas. SUMMARY
[0005] In view of the above problems, the present application aims to provide a slope top / bottom line extraction system and method to solve the problems of time-consuming and inefficient traditional pit slope top / bottom line method, and excessive labor input and consumption cost.
[0006] The slope top / bottom line extraction system provided by the present application mainly includes a data preprocessing unit, a gray-scale image edge extraction unit, and a slope top / bottom line extraction output unit. Wherein,
[0007] The data preprocessing unit is configured to preprocess the pre-acquired mining area DEM image, so that the edge extraction image processing of the gray-scale image edge extraction unit is not affected by the edge noise in the mining area DEM image.
[0008] The gray-scale image edge extraction unit is configured to perform gray-scale image edge extraction processing on the denoised mining area DEM gray-scale image.
[0009] The slope top / bottom line extraction unit is configured to extract the slope top / bottom line from the mining area DEM gray-scale image on which the gray-scale image edge extraction processing has been performed.
[0010] In addition, the optional technical solution is that the data preprocessing unit includes:
[0011] an image conversion module, configured to convert a pre-acquired mine area DEM image into a grayscale image;
[0012] an encryption module, configured to perform encryption processing on the converted grayscale image by using a bilinear interpolation method;
[0013] a denoising module, configured to perform bilateral filtering processing on the encrypted grayscale image.
[0014] In addition, the optional technical solution is that the grayscale image edge extraction unit comprises:
[0015] a gradient operation module, configured to perform gradient calculation on the mine area DEM grayscale image, so as to improve the object contour and level sense in the mine area DEM grayscale image;
[0016] a threshold interval calculation module, configured to calculate a threshold interval of the mine area DEM grayscale image by using an OTSU algorithm, divide the mine area DEM grayscale image into two parts of background and target according to grayscale characteristics, and make the maximum segmentation of the inter-class variance to minimize the misclassification probability;
[0017] an edge extraction module, configured to extract a slope top / bottom line according to the threshold interval of the mine area DEM grayscale image
[0018] On the other hand, the present application also provides a slope top / bottom line extraction method, which extracts the slope top / bottom line by using any one of the above slope top / bottom line extraction systems; the method comprises: pre-processing a pre-acquired mine area DEM image, so that the edge extraction image processing of the grayscale image edge extraction unit is not affected by edge noise in the mine area DEM image;
[0019] performing grayscale image edge extraction processing on the denoised mine area DEM grayscale image;
[0020] extracting the slope top / bottom line in the mine area DEM grayscale image which has undergone the grayscale image edge extraction processing.
[0021] The above slope top / bottom line extraction system and method automatically extract a characteristic line based on a mine area DEM image, and distinguish the slope top / bottom line according to elevation and slope information, determine the best region of interest window size suitable for different slope intervals through experiments on multiple groups of mine pits of different regional types, greatly reduce the amount of calculation and improve the processing efficiency. In addition, the OTSU algorithm is combined to automatically calculate the upper and lower thresholds to achieve self-adaptation, and the strong and weak edges of the texture can be effectively retained, thereby solving the actual needs of digital mine construction management, and facilitating the mine construction to quickly obtain the slope top / bottom line of the mine pit.
[0022] To the accomplishment of the foregoing and related ends, one or more aspects of the application comprise the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the application. These aspects are indicative, however, of but a few of the various ways in which the principles of the application can be employed. Other aspects and advantages of the application will be made apparent by consideration of the following detailed description and drawings. BRIEF DESCRIPTION OF DRAWINGS
[0023] Other objects and advantages of the application will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
[0024] Figure 1 A schematic diagram of a logical structure of a slope top / bottom line extraction system according to an embodiment of the application;
[0025] Figure 2 A schematic diagram of bilinear interpolation according to an embodiment of the application;
[0026] Figure 3 An operation method of a gradient operation module according to an embodiment of the application;
[0027] Figure 4 A technical flow of performing slope top / bottom line extraction according to an embodiment of the application;
[0028] Figure 5 A comparative schematic diagram of slope top / bottom line extraction results applying the application;
[0029] Figure 6 A flow of a slope top / bottom line extraction method according to an embodiment of the application.
[0030] Reference signs in the drawings comprise:
[0031] The same reference signs in all the drawings indicate corresponding or similar features or functions. DETAILED DESCRIPTION
[0032] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding of one or more embodiments. However, it will be apparent to those skilled in the art that the various embodiments can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices and methods are omitted so as not to obscure the description of the various embodiments.
[0033] In order to make the technical solution of the present application clearer, first, the following part will make an explanation and description of some technical data involved in the present application.
[0034] Ridge line, slope bottom line: the mine pit step is composed of the upper flat disc, the lower flat disc, the step slope surface, the step ridge line, the step slope bottom line, the step height and the step slope surface angle and other elements. The upper flat disc and the lower flat disc of the step are relative, and the upper flat disc of the step is also the lower flat disc of the step above it; the intersection lines of the upper flat disc, the lower flat disc and the step slope surface are respectively called the step slope surface top line and the step slope surface bottom line.
[0035] Digital Elevation Model (DEM): It is a kind of entity ground model expressed by a set of ordered numerical array form representing ground elevation, and realizes digital simulation of ground terrain (i.e. digital expression of terrain surface morphology) through limited terrain elevation data.
[0036] OTSU algorithm: also known as maximum inter-class difference method, it is an algorithm for selecting threshold value in image segmentation, and the inter-class variance of the foreground and background images is maximum after the image is binarized and segmented according to the threshold value obtained according to the algorithm.
[0037] In order to solve the problems of time-consuming and low efficiency, too much manual input and consumption cost of the traditional mine pit slope top / bottom line method, the present application provides a slope top / bottom line extraction system and method, which automatically extracts feature lines of the mine pit slope DEM based on the original airborne laser radar point cloud, and discriminates the slope top / bottom line according to the elevation and slope information. The mine pit slope top / bottom line automatically generated by the slope top / bottom line extraction system significantly improves the production efficiency under the premise of confirming the accuracy compared with the mine pit slope top / bottom line extracted by the traditional manual extraction method; compared with the current existing DEM-based slope top / bottom line extraction method, the parameter threshold of the internal processing flow of the slope top / bottom line extraction system is self-adaptive; the whole process is automatically realized without manual parameter adjustment, and the fine classification results of the mine pit and nearby objects can be obtained in the processing process; and the three-dimensional model can be compared and visualized.
[0038] After the slope top / bottom line is automatically drawn by the slope top / bottom line extraction system, the point coordinates are output at a certain interval to obtain the spatial position information, and the effective results of various types are output to guide the actual construction on site.
[0039] In order to describe the slope top / bottom line extraction system and method in detail, the specific embodiments of the present application will be described in detail below with reference to the drawings.
[0040] Figure 1 The logical structure schematic diagram of the slope top / bottom line extraction system according to the embodiment of the present application is shown.
[0041] As Figure 1As shown, the slope top / bottom line extraction system provided by the embodiment mainly comprises a data preprocessing unit 110, a gray image edge extraction unit 120 and a slope top / bottom line extraction output unit 130.
[0042] The data preprocessing unit 110 is configured to preprocess the pre-acquired mine area DEM image to ensure that subsequent image processing such as edge detection is not affected by edge noise in the DEM.
[0043] Specifically, as an example, the data preprocessing unit 110 further comprises an image conversion module 112, an encryption module 114 and a denoising module 116.
[0044] The image conversion module 112 is configured to convert the pre-acquired mine area DEM image into a gray image; the encryption module 114 is configured to perform encryption processing on the converted gray image by using a bilinear interpolation method; and the denoising module 116 is configured to perform bilateral filter processing on the encrypted gray image.
[0045] Specifically, the image conversion module 112 first performs upsampling on the pre-acquired mine area DEM image by bilinear interpolation to improve the picture resolution, and then converts the mine area DEM image with improved resolution into a mine area DEM gray image.
[0046] Based on the advantages of fast speed and strong stability shown in the calculation process of the current bilinear interpolation method, the encryption module 114 performs encryption processing on the converted mine area DEM gray image by using the bilinear interpolation method. Through the encryption processing, the resolution of the image can be effectively improved, for example, from two rows and two columns to four rows and four columns.
[0047] Figure 2 A schematic diagram of bilinear interpolation according to an embodiment of the present application is shown.
[0048] As Figure 2 shown, the process of the encryption module 114 performing encryption processing on the converted mine area DEM gray image by using the bilinear interpolation method includes:
[0049] The four known data points closest to the interpolation point are used to form a quadrilateral, so as to determine a bilinear polynomial to interpolate the elevation of the interpolation point. In a specific embodiment of the present application, 3 times of single linear interpolation is performed from two directions;
[0050] Based on the above bilinear polynomial, first, linear interpolation is performed along the x direction, and the respective elevations of the two interpolation points are obtained as follows:
[0051]
[0052]
[0053] wherein R1, Q 11 , R1, Q 11 represent the position of a point in the coordinate system shown in Figure 2 , x, y are the coordinates of their points.
[0054] Secondly, linear interpolation in the y direction is performed, and the P point obtained by the x direction interpolation is:
[0055]
[0056] The denoising module 116 is configured to perform bilateral filtering processing on the encrypted grayscale image. The bilateral filtering is a compromise processing combining the spatial proximity and the pixel value similarity of the image, which simultaneously considers the spatial domain information and the grayscale similarity, so that the edge information of the image is protected, and the purpose of edge-preserving denoising is achieved.
[0057] The grayscale image edge extraction unit 120 is configured to perform grayscale image edge extraction processing on the denoised mine area DEM grayscale image, and includes a gradient operation module 122, a threshold interval calculation module 124, and an edge extraction module 126.
[0058] The gradient operation module 122 is configured to change the mine area DEM grayscale image with unclear blur, unclear outline, and unclear edge grayscale change into the mine area DEM grayscale image with clear object outline change and strong level sense by calculation. Specifically, the gradient operation module 122 uses the derivative (gradient) to measure the change rate of the grayscale of the mine area DEM grayscale image, and regards the image gradient as a two-dimensional discrete function, and the image gradient is the derivative of the two-dimensional discrete function.
[0059] As an example, Figure 3 The operation method of the gradient operation module according to the embodiment of the present application is shown. As Figure 3 shown, the operation method of the gradient operation module 122 is as follows: assuming that the original image pixel point 100 and 90 brightness difference is 10, the new image pixel brightness difference after addition is 20, the contrast is obviously enhanced, and the difference with the background is increased, Figure 3 only a single direction is described in the above formula (3), and the gradients in the x and y directions are combined to be represented by the following formula (4): the gray value of a certain point is calculated by multiplying the gray value of each pixel and the corresponding position element and summing (similar to the convolution in CNN, which is actually a correlation operation), and the non-square root approximation is usually used to improve the efficiency:
[0060]
[0061] wherein M(x, y) represents the gradient in the x and y directions, g x represents the x direction brightness of a certain pixel of the original image, gy This represents the brightness of a pixel in the y-direction of the original image.
[0062] Furthermore, the gradient direction can be calculated using the following formula (5):
[0063]
[0064] In one specific embodiment of the present invention, the threshold interval calculation module 124 uses the OTSU algorithm to calculate the threshold interval of the grayscale image of the mining area DEM, so as to avoid the complex calculation process of manually defining the ROI region and calculating the standard deviation in the previous method, and achieve an adaptive effect, so that the grayscale image of the mining area DEM is divided into two parts, background and target, according to the grayscale characteristics of the image itself, and the maximum segmentation of the inter-class variance minimizes the probability of misclassification.
[0065] Specifically, as an example, the OTSU algorithm is used to first calculate the image histogram, that is, the number of pixels falling in each Bin (256 Bins in total, from 0 to 255). Then, the histogram is normalized, and a gray level threshold i is manually input for iteration starting from 0.
[0066] The adaptive process for the global threshold of the mine DEM grayscale image is as follows:
[0067] The proportion ω0 of foreground pixels (levels 0-i) in the entire image is calculated, and the average gray level u0 of the foreground pixels is also calculated. The proportion ω1 of background pixels (levels i-255) in the entire image is calculated, and the average gray level u1 of the background pixels is also calculated. Therefore, the average gray level of the mining area DEM grayscale image is u2, calculated using the following formula:
[0068] u2=ω0*u0+ω1*u1 Formula (6)
[0069] The inter-class variance g of the grayscale image of the mine DEM is given by the following formula:
[0070] g = ω0(u0 - u2) 2 +ω1(u1-u2) 2 Formula (7)
[0071] The final result is: g = ω0ω1(u0 - u1) 2 Formula (8)
[0072] The iteration ends when i = 256, and the i value corresponding to the maximum value of g is used as the global threshold of the mine DEM grayscale image.
[0073] The slope top / bottom line extraction unit 130 is used to extract the slope top / bottom line based on the threshold range (i.e., the global threshold) of the grayscale image of the mining area DEM.
[0074] Specifically, after the global threshold is determined, the edge of the mine DEM image can be defined according to the global threshold, so as to determine the edge of the gray image. For the edge of the gray image determined in this way, the width of the connected line segments is inconsistent, and therefore, the width needs to be uniformly processed first, so as to extract the center connecting line of the pixel block as the final slope top / bottom line; for the line extracted after the width of the edge feature line is processed, the elevation values corresponding to the pixel blocks of the two lines are compared, so that it can be judged whether the extracted line is a slope top line or a slope bottom line.
[0075] The processing mode of the pixel corresponding to the elevation is as follows: according to the mine DEM gray image after the bilinear interpolation, the resolution output D x and D y of the x and y directions are obtained.The x and y direction coordinates of the upper left corner point of the mine DEM gray image are Xcord and Ycord, and the pixel resolution coordinates are one-to-one corresponding to the image coordinates through the following formula (9) and formula (10), wherein:
[0076] x=X cord cord+j×D x Formula (9)
[0077] y=Y cord cord+j×D y Formula (10)
[0078] wherein D x and D y are the resolutions of the X and Y directions in the grid image, and the actual coordinates (x, y) of each point can be calculated through the formula (9) and (10), wherein i and j are the row number and column number of the point respectively.
[0079] Figure 4 The technical process of extracting the slope top / bottom line according to the embodiment of the present application is shown in FIG. 1, after the original mine area DEM image is obtained: Figure 4
[0080] Firstly, the original mine area DEM image needs to be pre-processed, which includes converting the DEM elevation data image into a gray image, bilinear interpolation encryption and bilateral filter denoising.
[0081] Then, the edge of the gray image is extracted, which includes gray image gradient operation and threshold interval calculation through OTSU algorithm, wherein if the calculated threshold interval is greater than the upper limit of the threshold, it is determined that the pixel gray value of the gray image is 0; otherwise, it is continued to be judged whether the calculated threshold interval is less than the lower limit of the threshold, if it is less than the lower limit of the threshold, it is determined that the pixel gray value of the gray image is 255, otherwise, it is determined that the pixel gray value of the gray image is 128. According to the above determination, the edge of the gray image can be determined.
[0082] Finally, according to the determined edge of the gray image, the top / bottom line of the slope surface is extracted and output. It includes: firstly, the edge feature line width processing is performed according to the determined edge of the gray image, and then it is judged whether the line is the top / bottom line of the slope surface.
[0083] Since the extracted top / bottom line of the slope surface is in the form of a pixel block, the number of pixels extracted in the same direction is inconsistent, which leads to inconsistent width of the connected line segment, and therefore, the width needs to be uniformly processed, so as to extract the center connecting line of the pixel block as the final top / bottom line of the slope surface; for the line extracted after the width processing of the edge feature line, the elevation values corresponding to the pixel blocks of the two lines are compared, and it can be judged whether the extracted line is the top line or the bottom line of the slope surface.
[0084] Figure 5 A comparison diagram of the top / bottom line of the slope surface extracted by using the original DEM and the result of the application is shown.
[0085] It can be seen from the comparison diagram of the above embodiment and Figure 4 that the top / bottom line extraction system of the application extracts the top / bottom line of the slope surface by using the OTSU algorithm with adaptive threshold to segment the DEM image of the mining area, so that the gray value of the pixel corresponds to the elevation one by one, thereby dividing the DEM gray image of the mining area into two parts, and effectively identifying the top / bottom line of the slope surface.
[0086] Corresponding to the above-mentioned top / bottom line extraction system, the application further provides a top / bottom line extraction method of the slope surface, specifically, Figure 6 a flowchart of the top / bottom line extraction method of the slope surface according to the embodiment of the application is shown.
[0087] As shown in Figure 6 , the top / bottom line extraction method of the slope surface of the embodiment of the application mainly includes:
[0088] S610: The pre-acquired DEM image of the mining area is pre-processed, so that the edge extraction image processing of the gray image edge extraction unit is not affected by the edge noise in the DEM image of the mining area;
[0089] S620: The top / bottom line of the slope surface is extracted in the DEM gray image of the mining area which has been subjected to the gray image edge extraction processing;
[0090] S630: The DEM gray image of the mining area after the noise removal is subjected to the gray image edge extraction processing.
[0091] In addition, after the top / bottom line of the slope surface is extracted, it further includes outputting the extracted top / bottom line of the slope surface.
[0092] It should be noted that the embodiments of the slope top / bottom line extraction method can refer to the description in the above-described embodiments of the slope top / bottom line extraction system, which will not be repeated here.
[0093] According to the slope top / bottom line extraction system and method of the present application, through a series of preprocessing operations such as filtering and denoising of the original DEM image, the gray image is segmented, and the OTSU algorithm is applied, which can realize adaptive threshold interval in different terrain conditions, avoid incorrect classification caused by artificial input of empirical values, and complete the automatic extraction of the slope top / bottom line through line thinning and broken line connection in the subsequent extraction process. Through experimental analysis, the method can quickly and accurately obtain the slope top / bottom line only with the real DEM of the mining area, greatly improves the work efficiency compared with the traditional measurement method, and solves the practical problems in engineering.
[0094] The slope top / bottom line extraction system and method according to the present application are described above with reference to the accompanying drawings by way of example. However, those skilled in the art should understand that various improvements can be made to the slope top / bottom line extraction system and method of the present application without departing from the content of the present application. Therefore, the protection scope of the present application should be determined by the content of the appended claims.
Claims
1. A slope top / base line extraction system characterized by, The slope top / bottom line extraction system mainly comprises a data preprocessing unit, a gray image edge extraction unit and a slope top / bottom line extraction output unit. The data preprocessing unit is used for preprocessing the pre-acquired mine area DEM image, so that the edge extraction image processing of the gray image edge extraction unit is not affected by the edge noise in the mine area DEM image. The gray image edge extraction unit is used for performing gray image edge extraction processing on the denoised mine area DEM gray image. The slope top / bottom line extraction unit is used for extracting the slope top / bottom line from the mine area DEM gray image which has been subjected to the gray image edge extraction processing. The data preprocessing unit comprises: An image conversion module is used for converting the pre-acquired mine area DEM image into a gray image. An encryption module is used for performing encryption processing on the converted gray image by using a bilinear interpolation method. A denoising module is used for performing bilateral filtering processing on the encrypted gray image. The gray image edge extraction unit comprises: A gradient operation module is used for performing gradient calculation on the mine area DEM gray image, so as to improve the object contour and level sense in the mine area DEM gray image. A threshold interval calculation module is used for calculating the threshold interval of the mine area DEM gray image by using an OTSU algorithm, dividing the mine area DEM gray image into two parts of background and target according to the gray characteristics, and minimizing the misclassification probability by maximum segmentation of the inter-class variance. An edge extraction module is used for extracting the slope top / bottom line according to the threshold interval of the mine area DEM gray image.
2. The slope edge / top line extraction system of claim 1, wherein, The image conversion module first performs upsampling on the pre-acquired mine area DEM image by using bilinear interpolation, so as to improve the picture resolution, and then converts the mine area DEM image with improved resolution into a mine area DEM gray image.
3. The slope edge / top line extraction system of claim 1, wherein, The encryption module performs encryption processing on the converted gray image by using a bilinear interpolation method, which comprises the following steps: Four known data points closest to the interpolation point are used to form a quadrilateral, so as to determine a bilinear polynomial to interpolate the elevation of the interpolation point. Based on the bilinear polynomial, linear interpolation is first performed along the x direction, so as to obtain the P points of the two points as follows: wherein R1, Q 11 , R1, Q 11 denote the position of points in the coordinate system shown in Fig. 2, x, y being the coordinates of their points; Secondly, linear interpolation is performed along the y direction, so as to obtain the P point of the two points as follows:
4. The slope edge / top line extraction system of claim 3, wherein, The gradient operation module uses the derivative to measure the change rate of the gray scale of the mine area DEM gray image.
5. The slope edge / top line extraction system of claim 4, wherein, The adaptive process of the global threshold of the mine area DEM gray image is as follows: The proportion of the foreground pixel 0-i level in the whole image is calculated as ω0, and the average gray scale of the foreground pixel is calculated as u0. The proportion of the background pixel i-255 level in the whole image is calculated as ω1, and the average gray scale of the background pixel is calculated as u1. The average gray scale of the mine area DEM gray image is u2, and the following formula is used: u2=ω0*u0+ω1*u1 Formula (6) g = ω0(u0-u2) 2 + ω1(u1-u2) 2 Equation (7) Finally, we obtain: g = ω0ω1(u0-u1) 2 Equation (8) The inter-class variance g of the mine area DEM gray image is calculated according to the following formula: Iteration is ended when i=256, and the i value corresponding to the maximum value of g is taken as the global threshold of the mine area DEM gray image.
6. The slope edge / top line extraction system of claim 5, wherein, The slope top / bottom line extraction unit extracts the slope top / bottom line from the threshold interval of the mine area DEM gray image, According to the resolution of x and y directions, the D x and D y , the x and y direction coordinates of the upper left corner of the image are X cord and Y cord , the pixel resolution coordinates are one-to-one corresponding to the image coordinates through the following formula (9) and formula (10), wherein: x = X cord + j x D x Equation (9) y = Y cord + j x D y Equation (10) where D x and D y are the resolutions in the X and Y directions of the grid map, and the actual coordinates (x, y) of each point are calculated by equations (9) and (10), where i and j are the row and column numbers of the point, respectively.
7. A method for extracting ridge / valley lines, characterized by, The method for extracting the slope top / bottom line by using the slope top / bottom line extraction system according to any one of claims 1 to 6 comprises: Preprocessing the pre-acquired mine area DEM image to make the edge extraction image processing of the gray image edge extraction unit not affected by the edge noise in the mine area DEM image; Performing gray image edge extraction processing on the denoised mine area DEM gray image; Extracting the slope top / bottom line from the mine area DEM gray image on which the gray image edge extraction processing is performed.
8. The ridge / top line extraction method of claim 7, wherein, After the slope top / bottom line is extracted, the method further comprises: Outputting the extracted slope top / bottom line.