Continuous within query in road networks

In recent years, the research community introduced various methods for processing spatio-temporal queries. Continuous Within query (and CWQ) is an important type of spatio-temporal queries with many real applications. A CWQ can be used to find the moving objects whose distances to the moving query object are less than or equal to a user-given distance d_ε at each time instant. In this paper, we study how to efficiently process the CWQ in road networks, where the criterion for determining the CWQ result is the road distance between objects. We propose an efficient algorithm, namely the continuous within query (CWQ) algorithm, combined with a road distance model to answer the CWQ. Extensive experiments using real road network dataset demonstrate the effectiveness and the efficiency of the proposed algorithm.