一种基于固定网络的移动对象运动轨迹索引模型

Indexing Moving Objects Trajectories on Fixed Networks

实际应用中移动对象通常运动在城市固定道路上,针对此特征研究人员已提出一些相关索引模型,但都存在一定的局限性,表现为索引模型只管理对象的历史位置信息或实时位置信息以及只对窗口查询或轨迹查询进行优化.IMTFN是一种基于固定网络的移动对象运动轨迹索引模型,管理移动对象的实时位置信息和历史轨迹信息,并且有效优化窗口查询及轨迹查询操作.IMTFN由一个管理固定网络的2DR-Tree、一组管理移动对象运动轨迹的1DR-Tree以及记录移动对象实时位置信息的Hash结构组成.最后通过实验IMTFN分别与STR-Tree与FNR-Tree进行性能比较,证明IMTFN模型提供速度更快的查询操作.

In a kind of spatiotemporal database applications, objects move on the road networks. To process the position information for such kind of moving objects, people have proposed some index models, but they all have their limitations. These models are unable to index both the present and past positions of moving objects. Meanwhile, they only support window query or trajectory query. A new indexing technique which is called indexing moving objects trajectories on fixed networks （IMTFN） is proposed in this paper. IMTFN consists of a 2-dimensional （2D） R^＊-Tree for managing the fixed networks, a forest of 1- dimensional （1 D） R^＊ -Trees indexing the time interval for managing the position of moving objects, and a hash structure for the newest location of moving objects. IMTFN supports the efficient query of the present and past positions of moving objects, optimizes operations of windows query and trajectory query. Extensive experiments are conducted to evaluate the performance of the proposed indexing mechanism and show that IMTFN performs considerably better than STR Tree and FNR-Tree.