Representing and reasoning about changing spatial extensions of geographic features

摘要

This thesis presents a novel approach to representing and reasoning about geographic\udphenomena which can be interpreted based on changes affecting spatial extensions of\udgeographic features. Of particular interest in this work are geographic features whose\udextensions can be described as 2-dimensional regions corresponding to portions of the\udearth surface under a specified projection, such as deserts, forests and oceans.\udThe work resulted in the development of a logical framework for representing geographic\udevents and processes. In developing such a framework, issues have been addressed\udregarding the relationship between these concepts and also between them and\udgeographic features. Other crucial issues are how to define the relation between event\udand process types and their particular instances, and how to handle different kinds of\udvagueness to associate specific spatial and temporal boundaries with those instances.\udOf particular interest in this work is the development of a method of explicitly linking\udthe formalism to spatio-temporal data. This requires work at multiple levels, both in\udconsideration of how the data can be represented and in regards of how primitive elements\udof the logical framework can be defined.\udAlthough data can be regarded as a faithful reproduction of physical elements of the\udworld, some conceptual elements are not always explicitly represented within data. For\udthat reason, a logic-based approach to representing spatio-temporal geographic data was\udalso developed and is presented in this thesis. Representing the data in a logical fashion\udallows implicit data to be derived by means of logical inferences, and provides a natural\udway of explicitly connecting the data to a semantic-based formalism. Derived data\udmay include spatial extensions of geographic features at different times, based on existing\uddata describing, for example, portions of the earth’s surface associated with different\udobservable properties.\udFurthermore, a system has been implemented to evaluate the applicability of the proposed\udtheory. The system takes time-stamped topographic data as an input and allows\udlogical queries to be formulated about the data, returning textual and graphical information\udon geographic events, processes, and features which participate in them.