Air-FAR: Fast and Adaptable Routing for Aerial Navigation in Large-scale Complex Unknown Environments

This paper presents a novel approach for realtime 3D navigation in large-scale complex environments by introducing a hierarchical 3D visibility graph (V-graph) and an efficient path search method. The proposed algorithm addresses the computational challenges of V-graph construction and shortest path search on the graph simultaneously. By introducing hierarchical 3D V-graph construction with heuristic visibility update, the 3D V-graph is constructed in $O\left(K \cdot n^{2} \log n\right)$ time, which guarantees real-time performance. The proposed iterative divide-and-conquer path search method can achieve near-optimal path solutions within the constraints of realtime operations. The algorithm ensures efficient 3D V-graph construction and path search. Extensive simulated and realworld environments validated that our algorithm reduces the travel time by 42%, achieves up to 24.8% higher trajectory efficiency, and runs faster than most benchmarks by orders of magnitude in complex environments. The code and developed simulator have been open-sourced to facilitate future research.