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UBC Theses and Dissertations

Approximate spatial reasoning using vague objects Kennedy, Kevin


A method is proposed for implementing spatial reasoning and spatial knowledge representation on a computer which utilizes a new concept named vague objects. Vague objects are an approximate representation system both for solid objects and for spatial relationships between two or more solid objects. A vague object is a simplified solid ob ject where sharp surfaces are replaced with smooth transitions from the solid to its sur roundings. A vague object can be compared to a cloud with a smoothly varying density that resembles a real solid object. Vague objects can be used to represent spatial concepts as well. A spatial concept is defined as a relation between objects, either solid or vague. Many spatial concepts can be visualized as vague objects, and for simple spatial reasoning, they can be implemented as such. Spatial reasoning with vague objects can be performed using a spatial logic that re sembles Venn diagrams in three dimensions. Spatial reasoning by means of vague objects can be executed sequentially in chains allowing complex spatial descriptions to be evalu ated in a visually understandable fashion. The reasoning system used is reminiscent of fuzzy logic, except that its domain of operation is in three dimensional space. Vague objects simulate some aspects of human spatial reasoning using methods in tended for implementation on a computer. This human-centred approach makes vague objects useful not only for emulating humans but, more importantly, for interacting with them.

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