Directional relations and frames of reference.

As an intermediate category between metric and topology, directional relations are as much varied as 'right of', 'before', 'between', 'in front of', 'back', 'north of', 'east of', and so on. Directional relations are ambiguous if taken alone without the contextual information described by frames of reference. In this paper, we identify a unifying framework for directional relations and frames of reference, which shows how a directional relation with its associated frame of reference can be mapped to a projective relation of the 5-intersection model. We discuss how this knowledge can be integrated in spatial query languages. [ABSTRACT FROM AUTHOR]