Unsupervised trajectory sampling

  • Authors:
  • Nikos Pelekis;Ioannis Kopanakis;Costas Panagiotakis;Yannis Theodoridis

  • Affiliations:
  • Dept. of Statistics and Insurance Science, Univ. of Piraeus, Greece;Tech. Educational Inst. of Crete, Greece;Dept. of Computer Science, Univ. of Crete, Greece;Dept. of Informatics, Univ. of Piraeus, Greece

  • Venue:
  • ECML PKDD'10 Proceedings of the 2010 European conference on Machine learning and knowledge discovery in databases: Part III
  • Year:
  • 2010

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Abstract

A novel methodology for efficiently sampling Trajectory Databases (TD) for mobility data mining purposes is presented. In particular, a three-step unsupervised trajectory sampling methodology is proposed, that initially adopts a symbolic vector representation of a trajectory which, using a similarity-based voting technique, is transformed to a continuous function that describes the representativeness of the trajectory in the TD. This vector representation is then relaxed by a merging algorithm, which identifies the maximal representative portions of each trajectory, at the same time preserving the space-time mobility pattern of the trajectory. Finally, a novel sampling algorithm operating on the previous representation is proposed, allowing us to select a subset of a TD in an unsupervised way encapsulating the behavior (in terms of mobility patterns) of the original TD. An experimental evaluation over synthetic and real TD demonstrates the efficiency and effectiveness of our approach.