Digital Outcrop Construction Of Karst Fracture Caves Based On Unmanned Aerial Vehicle And Lidar

As the goal of geological research tends to be refined and complicated,it is difficult to obtain the characteristic parameters of geological outcrop refinement through traditional methods.The multi-rotor UAV has good maneuverability and adaptability,and can provide multi-view geological outcrop images.The real-time 3D model constructed by tilt photogrammetry technology can provide accurate 3D coordinates.The ground lidar can quickly collect point cloud data,and the point cloud data can be used to quickly obtain a threedimensional model of the target to obtain accurate measurement data.In this paper,multi-rotor unmanned aerial vehicles and ground-based laser radars are used to extract data according to different outcrop parameter extraction needs and different outcrop environments.The highest resolution of the three-dimensional digital outcrop can reach millimeter level,which can restore the real scene in the field and realize Refinement and quantification of interpretation of geological phenomena.The main work and conclusions of the thesis are as follows:(1)Three-dimensional model construction of karst fracture cavern based on tilt imaging measurement of UAV.The non-measurement type camera on the drone is checked,and the image data of the experimental area is collected by the camera after the inspection,and the model is constructed by using two schemes: POS control point and POS no control point.Select some common features to measure the distance in the experimental area,the control point model and the controlless point model,and select two points of control points on the control point model and the non-control point model to obtain the corresponding coordinates.The azimuth of the point,through the accuracy analysis,obtains the length and azimuth accuracy measured on the model with POS uncontrolled points to meet the geological requirements.Then based on the geological survey,different multi-view image acquisition methods are proposed for different requirements of outcrop parameter extraction and different investigation environments.Finally,the oblique image measurement technology is used to process the acquired image data to obtain digital outcrops that meet geological requirements,and simple geological phenomena analysis and statistics are performed.(2)Three-dimensional model construction of karst fracture cavern based on ground lidar.In order to improve the efficiency of geological survey work,consider the environment of the survey area,and use the target as the splicing work of point cloud data.In order to get better splicing effect,analyze and obtain the optimal placement of target and ground lidar equipment shape.The control measurement of the point cloud data utilizes the coordinate frame provided by the image data of the drone and performs coordinate control.Finally,the point cloud data of the karst fracture hole is collected by the ground lidar equipment and the model is established.The obtained model is used to analyze and count the simple geological phenomenon.(3)The construction method of integrated digital outcrops inside and outside the karst fracture cave.In order to obtain the integrated model outside the hole in the digital outcrop cave of the karst fracture hole,the point cloud data generated by the multi-view image and the ground lidar point cloud data are merged.According to different fusion methods,it can be divided into location-based fusion and feature-based fusion.Based on the location and feature-based fusion case of the measured data,the integrated model of the karst fracture hole outside the hole is obtained.