## 5 Conclusions  
Based on the UAV-LiDAR system, the method of ground-based flight route planning was adopted in this study to obtain high-resolution images and high-precision LiDAR point-cloud data of the pit rim structural in a mountainous environment. Based on LiDAR point-cloud data processing, a high-precision DEM with a resolution of 0.2 m was built, and a 3D model was built using SfM-MVS technology. The multi-angle, qualitative, and quantitative topography feature identification, measurement, and analysis were achievedthrough visual interpretation, DEM visualization, GIS topographic feature extraction, analysis, and other methods. The aim of this study was to gain insights into and quantify the ability of the UAV-LiDAR method to identify and analyze topographic features in high-altitude and high-drop plateau mountain environments. The main conclusions were drawn as follows:  
(1) The UAV-LiDAR system adopted the ground-based flight route planning method, which was applicable to the complex topography environment. The elevation root mean square error of the 0.2 m high-resolution DEM from LiDAR was determined as 4.4 cm. The horizontal and elevation accuracy of the 3D model reached 4.4 cm and 7.9 cm, respectively. The data acquisition technology process based on UAV-LiDAR can provide a reference for obtaining high-quality data results. (2) The SIM and SVF visualization methods can highlight the topography features, extracting the dividing line between the inside and the outside. In general, the elevation ranged from 1540 m to 1580 m, mostly distributed outside, and the elevation tended to be decreased from north to south. The inside of the elevation reached 1660 m to 1700 m, and the central topography was the lowest. The mean maximum elevation difference of the ten ridges was determined as 161.12 m, and the mean maximum slope was 81.59\({}^{\circ}\). (3) The 0.2 m high-resolution DEM can retain the topographic details and provide basic data for refined section analysis. Most of the topography inside the pit rim structure was lower than the elevation of the dividing line, whereas the topography on both sides was the opposite. No significant difference was identified in the upper ridges. A gentle topography was obtained with the continuous extension of the ridges. The main change was at the end of the right ridge. (4) The mathematical statistics method can effectively analyze the results of the slope, aspect, and TWI topography feature parameters. The slope primarily ranged from 36\({}^{\circ}\) to 45\({}^{\circ}\). The aspects inside and outside were opposite, and the maximum slope value was more likely to occur outside. The aspect was largely east, and significant differences were identified in the distribution of light and heat resources. Moreover, there was abundant surface runoff, and no significant difference was identified in the distribution of TWI values inside and outside. The valleys formed between the outside ridges and on both sides of the ridges were rich in surface runoff, and soil erosion was significant. (5) The UAV-LiDAR system can provide fine basic data for the research on micro-topographic feature identification, measurement, and analysis. It has unparalleled advantages in extracting topographic feature information in the plateau and mountainous environment. The refined measurement and analysis will contribute to the further analysis of the correlation mechanisms of the formation and evolution of the topographical features and provide an important reference for the realization of high-precision 3D reproduction and quantitative analysis of micro-topography. [PERSON] performed the research and methodology, analyzed the data, and wrote the manuscript. [PERSON]. ([PERSON]) designed the framework of the research and mastered the conceptualization. [PERSON]. ([PERSON]) and [PERSON] gave many suggestions for improving and modifying this paper. [PERSON], [PERSON] and [PERSON] participated in data collection and investigation. [PERSON].