Measuring space-time prism similarity through temporal profile curves

Abstract

Space-time paths and prisms based on the time geographic framework model actual (empirical or simulated) and potential mobility, respectively. There are well-established methods for quantitatively measuring similarity between space-time paths, including dynamic time warping and edit-distance functions. However, there are no corresponding measures for comparing space-time prisms. Analogous to path similarity, space-time prism similarity measures can support comparison of individual accessibility, prism clustering methods and retrieving prisms similar to a reference prism from a mobility database. In this paper, we introduce a method to calculate space-time prism similarity through temporal sweeping. The sweeping method generates temporal profile curves summarizing dynamic prism geometry or semantic content over the time span of the prism’s existence. Given these profile curves, we can apply existing path similarity methods to compare space-time prisms based on a specified geometric or semantic prism. This method can also be scaled to multiple prisms, and can be applied to prisms and paths simultaneously. We discuss the general approach and demonstrate the method for classic planar space-time prisms.