I believe an approach that is based on Gibson’s idea of affordances is already off to a good start because it places human experiences, namely activities/tasks, as priority. Theoretically, it offers us an opportunity to escape from the daunting task of defining the precise boundaries of a river or the exact place a mountain ends as objects of reality and focus on how features allow activities to be performed. However, more importantly, I think it fits in nicely with Heidegger’s idea that nature is fundamentally revealing. According to him, there are two ways of things come into being, either through “phusis”, where a thing rises from itself and retrieves back into itself (flower blossoming) or through “techne”, where a craftsmen brings a thing comes into being (carpenter makes a bench out of wood). In short, a feature in the world reveals a certain part of itself to us depending on the task we seek to accomplish.
I think the paper could have been improved if the authors first give an overview of existing methods of ontology construction,, whether object-oriented or field-oriented, and discuss their advantages/disadvantages. In particular, which aspects are poorly served by constructing a GIS ontology through an object-oriented approach and how does the approach based in affordances address these issues. This comparison would have helped to demonstrate the strengths of their method more clearly. One questions arose while thinking about ontologies that supported activities. If an activity-oriented ontology is based on certain activities, I wonder then, if an ontology can be constructed for a map designed for general purposes like Google Map or Google Earth?