Querying Moving Objects with Uncertainty in Spatio-Temporal Databases

Abstract

Spatio-temporal uncertainty is a special feature of moving objects due to the inability of precisely capturing or predicting their continuously changing locations. Indeterminate locations of moving objects at time instants add uncertainty to their topological relationships. Spatio-temporal uncertainty is important in many applications, for example, to determine whether two moving objects could possibly meet. Previous approaches, such as the 3D cylinder model and the space-time prism model have been proposed to study the spatio-temporal uncertainty. However, topological relationships between uncertain moving objects have been rarely studied and defined formally. In this paper, we propose a model called pendant model, which captures the uncertainty of moving objects and represents it in a databases context. As an important part of this model, we define a concept called spatio-temporal uncertainty predicate (STUP) which expresses the development of topological relationships between moving objects with uncertainty as a binary predicate. The benefit of this approach is that the predicates can be used as selection conditions in query languages and integrated into databases. We show their use by query examples. We also give an efficient algorithm to compute an important STUP.