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Continuous Motion Pattern Query. Petko Bakalov, Vassilis J. Tsotras University of California, Riverside. Motivation. The need to locate spatio-temporal objects that follow specific patterns in streaming environment. Example:
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Continuous Motion Pattern Query Petko Bakalov, Vassilis J. Tsotras University of California, Riverside
Motivation • The need to locate spatio-temporal objects that follow specific patterns in streaming environment. • Example: Tracking the movement of law offenders and alerts the correctional officers for any suspicious or illegal behavior.
Definition • A Continuous Motion Pattern query Q is expressed as a sequence of n spatiotemporal predicates: • Qiis a spatial predicate, Tiis a relative time constraint, Ψiis a logical quantifier
Indexing • We need an appropriate spatiotemporal indexing structure that can accommodate positive and negative updates. • Such structure should answer efficiently questions of the type • Given area A, provide all objects that are not in A at the previous time instant but appear in A at the current instant (a + update) • Provide all objects that do not appear in A in the current time instant but were in A at the previous one(a - update)
Time T2 T1 1 2 3 Grid Cells One dimensional example Time To ……..… T2 Data Pages ………… T1 Time From T1 T2 1 2 3
One dimensional example • For any time period ( for example (3;6)) this space can be divided on 4 regions 3 2 Time to Region 1 7 6 Region 2 5 1 4 4 Region 3 3 2 Region 4 1 1 2 3 4 5 6 7 Time from