arXiv:2410.15715cs.DScs.AI2024-10被引 3

用计算几何优化公交网络路径搜索,提速显著。

Timetable Nodes for Public Transport Network

  • 引入时刻表节点(TTN)预处理,改进图模型搜索效率。
  • 将节点扩展复杂度从O(k×log|C|)降至O(k+logk+log|C|),提升明显。
  • 适用于高密度公交网络,可集成至其他路径算法中。

在依赖时间的交通网络中实现快速路径规划是导航系统中的重要且具有挑战性的问题。交通网络主要分为道路网络与公共交通线路网络两类。针对道路网络表现良好的方法(如时间依赖的收缩层次结构)通常不适用于公共交通网络。在公共交通网络中,非图方法(如CSA和RAPTOR)相比图方法表现出更优性能。本文提出一种新方法,通过引入计算几何中的优化技术,提升图方法在公共交通网络中的搜索速度。我们设计了一种新的预处理步骤,称为时刻表节点(Timetable Nodes, TTN)。该方法灵感来自计算几何中的迭代搜索问题。实现两种版本:使用合并搜索树(TTN-CST)和分数级联(TTN-FC)。两者均将到达新节点的时间复杂度从O(k×log|C|)降低至O(k + log(k) + log(|C|)),其中k为节点的出边数,|C|为时刻表信息总规模(即总出边数)。本方法适用于任意时间依赖网络,可与其他路径规划算法集成。实验表明,该预处理在高密度图上显著提升性能。研究展示了如何利用计算几何改进交通网络路径规划,使大规模出边场景下的路径搜索更快。

原文摘要 · Abstract (English)

Faster pathfinding in time-dependent transport networks is an important and challenging problem in navigation systems. There are two main types of transport networks: road networks for car driving and public transport route network. The solutions that work well in road networks, such as Time-dependent Contraction Hierarchies and other graph-based approaches, do not usually apply in transport networks. In transport networks, non-graph solutions such as CSA and RAPTOR show the best results compared to graph-based techniques. In our work, we propose a method that advances graph-based approaches by using different optimization techniques from computational geometry to speed up the search process in transport networks. We apply a new pre-computation step, which we call timetable nodes (TTN). Our inspiration comes from an iterative search problem in computational geometry. We implement two versions of the TTN: one uses a Combined Search Tree (TTN-CST), and the second uses Fractional Cascading (TTN-FC). Both of these approaches decrease the asymptotic complexity of reaching new nodes from $O(k\times \log|C|)$ to $O(k + \log(k) + \log(|C|))$, where $k$ is the number of outgoing edges from a node and $|C|$ is the size of the timetable information (total outgoing edges). Our solution suits any other time-dependent networks and can be integrated into other pathfinding algorithms. Our experiments indicate that this pre-computation significantly enhances the performance on high-density graphs. This study showcases how leveraging computational geometry can enhance pathfinding in transport networks, enabling faster pathfinding in scenarios involving large numbers of outgoing edges.

路径规划公交网络计算几何图算法

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