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An efficient management method of moving spatial objects

A spatio-temporal data structure, called the PMD-tree (persistent multi-dimensional tree), has been proposed for managing the live intervals and locations of spatial objects. In the paper, novel concepts of time space bounding box (TSBB) and motion list are introduced to the PMD-tree to manage moving spatial objects efficiently. TSBB is an extended bounding box for a moving object that covers the trajectory of the object. As an object moves, a TSBB corresponding to the object is enlarged to enclose the trajectory of the object. A TSBB is divided when it becomes greater than a limit. An object and corresponding TSBBs are managed by a doubly connected linked list, called a motion list. TSBBs are also managed by the PMD-tree. By introducing the concept of TSBB and motion list to the PMD-tree, moving objects can be efficiently managed and quickly found for spatio-temporal queries. By carrying out a series of simulation tests, the storage requirements and search performances are evaluated for several types of moving objects.