## 1 Introduction  
Yunnan lies within a transitional zone between the southeastern margin of the Qinghai-Tibet Plateau and the southern Yunnan-Guizhou Plateau. Shaped by multiple tectonic events and west-to-east descending terrain, the region is characterized by deeply incised gorges in the Hengduan Mountains, fault escarpments in central Yunnan, and karst cliffs in the east. These geological features collectively result in fractured rock masses highly prone to instability. Under gravitational loading or external triggers such as earthquakes and intense rainfall, unstable rock blocks may rapidly move via toppling, rolling, or free fall, resulting in typical rockfall hazards [1; 2; 3]. These events are abrupt, short-lived, and difficult to predict. High-velocity rockfalls can cause severe damage to infrastructure such as roads and bridges. Their cascading impacts are often more destructive than those of landslides or debris flows [4; 5]. In 2024, the Lujiawan resettlement site was impacted by a series of compound disasters, including debris flows and deformations triggered by rainfall. On 24 June, a debris flow carrying large boulders blocked the drainage culvert, resulting in a deposit of approximately 3500 m\({}^{3}\). The event destroyed 30 m of steel pipe guardrails, damaged around 2 acres of farmland and 50 m of drinking water pipelines, and caused direct economic losses of approximately 300,000 yuan. On 5 September, intense rainfall triggered large-scale slope deformation, prompting the emergency relocation of two households. Therefore, developing a refined system for assessing rock mass stability and predicting three-dimensional rockfall trajectories has become a central task for disaster mitigation in Yunnan's mountainous gorge regions. This system also provides essential technical support for the long-term safety management of transportation, energy, and urban infrastructure in mountainous areas. Rock slope stability is primarily governed by the orientation and configuration of structural planes. Stereographic projection methods allow intuitive identification of instability modes such as planar sliding, wedge sliding, and toppling failures [6; 7], serving as effective tools for qualitative screening. Subsequently, the limit equilibrium method is used to calculate safety factors, enabling a coupled diagnostic approach that combines qualitative identification with quantitative analysis. In recent years, high-precision point cloud technologies--such as 3D laser scanning and UAV (unmanned aerial vehicle) photogrammetry--have developed rapidly, offering rich datasets for structural analysis. High-density point clouds enable detailed representation of rock surface geometries and joint distributions, greatly improving the efficiency of structural plane information extraction [8]. Intelligent structural plane recognition based on 3D laser scanning enables high-precision extraction of geometric features such as faults and fractures in rock slopes, offering critical parameters for quantitative stability assessment [9]. Early studies have confirmed its feasibility in steep rock slopes [10], which has led to the development of various automated structural plane recognition algorithms. These algorithms have been integrated with discrete fracture network (DFN) models to quantitatively assess the stability of potential rock blocks [11]. Additionally, non-contact 3D scanning has been applied to monitor deformations of tunnel surrounding rocks and to measure structural planes, demonstrating strong adaptability in engineering practice [12]. The 3D point cloud technology enables high-resolution reconstruction of real-world environments, allowing safe and efficient acquisition of complete and accurate structural information for hazardous rock masses in complex terrains such as steep slopes. This provides reliable 3D model support for subsequent stability assessments [13]. Recent studies suggest that 3D laser scanning LiDAR has become an essential tool for high-precision modeling and stability assessment of hazardous rock masses.