3D GIS-Based Sustainable Spatial Planning of Low-Altitude Facilities Under a “Routine-Emergency Collaborative” Mode: A Case Study of Longji Terraces, China

Traditional 2D location models for unmanned aerial vehicles (UAVs) often lead to spatial distortions in complex mountainous environments, while single-purpose emergency facilities incur prohibitively high sunk costs. To address these issues, this study proposes a 3D GIS-based framework for optimizing low-altitude facility layouts under a “Routine-Emergency Collaborative Mode,” using the Longji Terraces in China as a case study. First, a high-fidelity 3D flight network is constructed by integrating oblique photogrammetry (OSGB) 3D models and DEM data, incorporating terrain-following and obstacle-avoidance strategies. Second, following the restructuring of demand nodes via hierarchical proximity clustering, P-Median and Maximum Coverage Location Problem (MCLP) models—coupled with sensitivity analyses—are applied for multi-scenario spatial allocation. The results demonstrate that: (1) the 3D topology accurately quantifies vertical impedance, effectively mitigating the physical conflict risks inherent in 2D modeling; (2) when balancing logistics efficiency with life-saving priorities, the optimal hubs exhibit a 75% spatial overlap, successfully enabling “routine-emergency” synergy; and (3) this collaborative mechanism reduces emergency response times in blind spots by 88.59%, securing the critical 15 min rescue window. Ultimately, this study provides a “true-3D” planning paradigm for resilient spatial governance in mountainous regions. By maximizing infrastructure economic efficiency through commercial logistics while ensuring public safety via rapid emergency responses, this methodology aligns with the Sustainable Development Goals (SDGs) and promotes the sustainable development of mountain tourism.