A Generic Framework for Continuous Motion Pattern Query Evaluation

We introduce a novel query type defined over streaming moving object data, namely, the continuous motion pattern (CMP) queries. A motion pattern is defined as a sequence of distinct spatial predicates, each attached to a temporal constraint. The spatial predicates can be of various types (range, nearest neighbor, etc.) The temporal constraints are relative to the current time instant and are used to specify the order of the spatial predicates on the time axis. A CMP query is continuously reevaluated over streaming spatiotemporal data, producing the moving objects which satisfy the query´s motion pattern. We first introduce an easily maintainable indexing scheme for spatiotemporal streams that facilitates the evaluation of the spatial predicates over their temporal constraints. Using this scheme we propose a generic framework for efficiently answering a wide range of CMP queries. The effectiveness of our algorithms in reducing the query computation cost and I/O operations is revealed through a thorough experimental evaluation.