In Marke Keane, Padraig Cunningham, Mike Brady, and Ruth Byrne (editors), AI and Cognitive Science '94, Proceedings of the Seventh Annual Conference, September 8-9, 1994, Trinity College Dublin, pages 103-113. Dublin University Press, 1994.
Abstract
We develop a calculus of line-of-sight relations, that is, the different qualitative relations in which one object in a person's visual field can be positioned relative to another. Examples of such relations are 'partially hides' and 'just hidden by'. We treat the system of such relations in a way that is analogous to the treatment of temporal intervals by Allen (1984) and Freksa (1992), and of spatial regions by Randell, Cui and Cohn (1992). We give the conceptual neighbourhood diagram for line-of-sight relations and show how to generate the composition table from the composition tables for two independent simpler relations whose direct product gives rise to the complete set of line-of-sight relations. The line-of-sight calculus is presented as a testing ground for qualitative reasoning techniques developed in the temporal and spatial domains, and is also proposed as having potential application to the field of computer vision.
Read the paper (Postscript file, 11 pages)
Note: An earlier version of this paper was presented at the AISB Workshop on Spatial and Temporal Reasoning held at Leeds University in April 1994.