Trajectory databases: data models, uncertainty and complete query languages

Abstract

Moving ob jects produce tra jectories. We describe a data model for tra jectories and tra jectory samples and an efficient way of modeling uncertainty via beads for tra jec- tory samples. We study transformations of the ambient space for which important physical properties of tra jectories, such as speed, are invariant. We also determine which transformations preserve beads. We give conceptually easy first-order com- plete query languages and computationally complete query languages for tra jectory databases, which allow to talk directly about speed and uncertainty in terms of beads. The queries expressible in these languages are invariant under speed- and bead-preserving transformations.