1. Computer-readable storage media, having computer-executable instructions stored thereon, that when executed, cause a computer processor to initiate: collecting locational data for multiple objects over a duration; grouping the locational data according to a plurality of sliding time intervals of variable length, the time intervals comprising portions of the duration; converting the locational data into polygons representing the locational data per time interval per object, wherein a size and/or a shape of the polygons represent object movement during a time interval; storing a size of the polygons in fields of a three-dimensional data structure, each field of the data structure corresponding to an object, a start time for a time interval, and a length of the time interval; and determining movement patterns of the objects based on the size and/or the shape of the polygons.