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Qualitative Representation of Planar Outlines

Richard Meathrel, Antony Galton

A new boundary-based scheme for qualitatively representing planar outlines is described, consisting of a set of seventeen ``atomic'' tokens, and based on a combined discretisation of tangent bearing, curvature, and the rate of change of curvature. By grouping together strings of atomic tokens, higher-level primitive curve tokens can be specified (PCTs), that correspond to localised curve features of greater abstraction. We show how the primitives of existing boundary-based schemes may be defined as PCTs, and how associated token ordering graphs can be constructed that visually encode token-string syntax, based on the ordering constraints implicit in a set of PCT specifications. Because of the atomic nature of its building blocks, we propose that the scheme can be developed into a general framework for constructing sets of task-specific primitives, for use in application areas such as computer vision and qualitative spatial reasoning.

Keywords: Knowledge Representation, Spatial Reasoning, Qualitative Reasoning

Citation: Richard Meathrel, Antony Galton: Qualitative Representation of Planar Outlines. In W.Horn (ed.): ECAI2000, Proceedings of the 14th European Conference on Artificial Intelligence, IOS Press, Amsterdam, 2000, pp.224-228.

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ECAI-2000 is organised by the European Coordinating Committee for Artificial Intelligence (ECCAI) and hosted by the Humboldt University on behalf of Gesellschaft für Informatik.