Representing and reasoning about changing spatial extensions of geographic features

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