Publicly available vessel trajectory data is emitted continuously from the global AIS system. Continuous trajectory similarity search on this data has applications in, e.g., maritime navigation and safety. Existing proposals typically assume an offline setting and focus on finding similarities between complete trajectories. Such proposals are less effective when applied to online scenarios, where similarity comparisons must be performed continuously as new trajectory data arrives and trajectories evolve. We therefore propose a real-time continuous trajectory similarity search method for vessels (ACTIVE). We introduce a novel similarity measure, object-trajectory real-time distance, that emphasizes the anticipated future movement trends of vessels, enabling more predictive and forward-looking comparisons. Next, we propose a segment-based vessel trajectory index structure that organizes historical trajectories into smaller and manageable segments, facilitating accelerated similarity computations. Leveraging this index, we propose an efficient continuous similar trajectory search (CSTS) algorithm together with a variety of search space pruning strategies that reduce unnecessary computations during the continuous similarity search, thereby further improving efficiency. Extensive experiments on two large real-world AIS datasets offer evidence that ACTIVE is capable of outperforming state-of-the-art methods considerably. ACTIVE significantly reduces index construction costs and index size while achieving a 70% reduction in terms of query time and a 60% increase in terms of hit rate.

翻译：公开可用的船舶轨迹数据持续从全球AIS系统发出。对此数据进行连续轨迹相似性搜索在海上导航与安全等领域具有应用价值。现有方案通常假设离线场景，并专注于发现完整轨迹之间的相似性。当应用于在线场景时，此类方案效果欠佳，因为相似性比较必须在新轨迹数据不断到达、轨迹持续演化的过程中连续进行。为此，我们提出一种面向船舶的实时连续轨迹相似性搜索方法（ACTIVE）。我们引入了一种新颖的相似性度量——物体轨迹实时距离，该度量强调船舶预期的未来运动趋势，从而实现更具预测性和前瞻性的比较。接着，我们提出一种基于分段的船舶轨迹索引结构，该结构将历史轨迹组织为更小且易于管理的片段，以加速相似性计算。基于此索引，我们提出一种高效的连续相似轨迹搜索（CSTS）算法，并结合多种搜索空间剪枝策略，以减少连续相似性搜索过程中不必要的计算，从而进一步提升效率。在两个大型真实世界AIS数据集上进行的大量实验证明，ACTIVE能够显著优于现有先进方法。ACTIVE显著降低了索引构建成本与索引大小，同时在查询时间上减少70%，并在命中率上提升60%。