关键词: 时空数据库, 轨迹距离, 兴趣点（POI）, 轨迹聚类

Abstract: Trajectories play an important role in analyzing the behavior of moving objects.Many researches have been conducted that retrieve similar trajectories of moving objects in Euclidean space rather than in road network space.However，in real applications，most moving objects are located in road network space.In this paper，the properties of similar trajectories are investigated in road network space and a spatio-temporal representation scheme is proposed for modeling the trajectories of moving objects.This spatio-temporal representation scheme effectively converts trajectory from the road network space to the Euclidean space.For measuring similarity between two trajectories，a new POI-distance algorithm is proposed which enhances the existing distance algorithm by reducing the insignificant nodes of a trajectory.Theory and experimental results show that this method provides not only a practical method for searching for similar trajectories but also a clustering method for trajectories.

Key words: spatio-temporal database, trajectories distance, Points Of Interesting（POI）, trajectories clustering