Ordered polyline trees for efficient search of objects moving on a graph

  • Authors:
  • Thuy Thi Thu Le;Bradford G. Nickerson

  • Affiliations:
  • Faculty of Computer Science, University of New Brunswick, Fredericton, N.B., Canada;Faculty of Computer Science, University of New Brunswick, Fredericton, N.B., Canada

  • Venue:
  • ICCSA'10 Proceedings of the 2010 international conference on Computational Science and Its Applications - Volume Part I
  • Year:
  • 2010

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Abstract

We discuss a spatio-temporal data structure to index objects moving on a graph. It is designed to efficiently answer rectangle R plus time instance and time interval queries about the past positions of moving objects. Such data structures are useful, for example, when searching which vehicles moving on a road network in specific areas at specific times. Unlike other data structures that use R-trees to index bounding boxes of moving object trajectories, our data structure indexes oriented line segments representing positions of moving objects at different times. For n moving object instances (unique entries of moving objects) on a graph with E edges, we show that $O(log_2 E + |L| log_2^2(n/E) + k)$ time is required to answer a rectangle R plus time interval query, for |L| the number of edges intersected by R and k the number of line segments containing moving object instances in range. Space O(n2/E+E) is required in the worst case to store n moving object instances in E ordered polyline trees. Space Ω(n+E) is required to store the history of all n moving object instances.