Extraction Of Open-pit Mine Step Line And Calculation Of Stripping Amount Based On UAV Images

With the development of the mining industry,the number of the open-pit mine in China has been increasing year by year,and the scale has continued to expand.The slopes and steps are the main structure of the open-pit mine.The step line can be used to calculate the geometric parameters such as the height of the step and the slope angle.Based on the change of the step line,the sliding and deformation of the slope can be detected and protected in time.Therefore,extracting the open-pit mine step line efficiently and accurately,generating the current state map of open-pit mining,and calculating the stripping amount have important application value for the production and safety of the open-pit mine.This paper analyzes the feature line extraction methods based on point cloud data at home and abroad and the stripping volume calculation method of open-pit mine.Aiming at the problems of low automation and low precision in the extraction of step line and the calculation of stripping volume in open-pit mines.Related studies on automatic extraction of step lines and automatic calculation of stripping volume have been carried out.The main contents of the research are as follows:1)This paper obtains the point cloud from the UAV sequence images of the open-pit mining area through the SFM and PMVS methods.Using the analysis of geometric properties of neighborhoods and curvature index weighting method proposed in this paper to extract the feature points of step line.The method uses progressive morphological filtering algorithm to preprocess the point cloud to remove the interference of artificial ground features such as retaining walls on the extraction of open-pit mine step lines.This paper performs curvature analysis on the point cloud data,and extracts potential feature points according to the curvature index,then optimize the normal vector through the Kd-tree index structure and RANSAC algorithm,and calculate the angle step and obtain the refined feature points.Finally,the moving least squares method is used to accurately fit the inner and outer characteristic lines of the steps.2)This paper proposes an oblique truncated triangular prism segmentation method to calculate the stripping volume of open-pit mine.Then,we construct a Delaunay triangulation network for the stripping area of open-pit mine for each period,and project each triangle to the elevation datum to form an oblique truncated triangular prism.This paper uses the segmentation method to find the volume addition,then add the volumes of all oblique truncated triangular prisms,make the difference between the summation results of the two periods to obtain the stripping volume.Finally,this paper compares the experimental results with the calculation results of Cloud Compare and LiDAR360 software.3)This paper uses the Microsoft Visual Studio 2017 compiler to perform secondary development of Cloud Compare under the Qt framework,and designs an open-pit mine step line extraction and stripping calculation based on point cloud data interface.The program code for feature line extraction and oblique truncated triangular prism segmentation method is written,and the functions of automatic extraction of step line and automatic calculation of stripping amount are realized.In order to verify the practicality of the algorithm in this paper,an iron ore mining area in Anshan City is selected as the experimental area.The experimental results show that the method proposed in this paper simplifies the manual operation,and can automatically,efficiently,and accurately extract the fine step line that conforms to the topographical change of the open-pit mine and automatically calculate the stripping amount.It has certain application value for the monitoring of slope step change,mine production and safety management in the open-pit mine.