Research Of Querying Moving Object Trajectories In Spatio-Temporal Databases

Spatio-Temporal Database is a new field in computer science. It is stimulated by kinds of applications(e.g. mobile communication systems, traffic control systems, transportation systems, digital battle field, geographical information systems and global positioning systems and so on).Recently, people have paid close attention to research of spatio-temporal database query methods commonly. Conventional query methods focus on searching static objects mainly. With the rapid advancement in wireless communications and positioning techniques, more and more application fields request database management systems to query moving object trajectories, including past trajectories, current and future trajectories of moving objects. The difficulty in such a case is that both the query and the objects change positions continuously, and therefore we can not rely on a given fixed reference position to determine the answer. Existing technique are either based on sampling, or on repetitive application of time-parameterized queries in order to provide the answer.On the basis of analyzing some spatio-temporal database query methods, this paper proposed an nearest neighbor query algorithm for answering dynamic querying moving object trajectories, based on which we proposed an reverse nearest neighbor query algorithm, and analyzed their cost. The proposed algorithms focus on querying current and future trajectories of moving objects, the dataset consists of moving point objects, which are organized by means of a time-parameterized R-tree (TPR-tree). The advantage of the proposed nearest neighbor query algorithm is that only one query is issued per time interval, overcoming the problem of repetitive queries, and improving query efficiency. Performance evaluation indicates that the cost of CPU and I/O achieves significant improvements compared to existing techniques. The proposed reverse nearest neighbor query algorithm is able to solve reverse nearest neighbor queries for continuously moving point trajectories in the plane. This research is important to development of spatio-temporal database query technology.