This dissertation investigates three topics related to movement and events associated with geospatial barriers. This research makes a unique contribution to geographic information science (GIScience), by examining how boundaries influence the interactions of other geographic features and to location-based services by bringing a GIScience perspective to geofence services. Chapters 2, 3, and 4 can be considered independently as journal articles. Each of these chapters builds on the previous. Chapter 2 serves as the base by examining geospatial barriers and impedance events associated with these barriers. The relationships between barriers, the features they protect and the features that they hinder are formalized in an ontology design pattern (ODP) that also includes events associated with these features. Algorithms are written to demonstrate the ODP can be used to answer queries about the presence or absence of barrier events.
Chapter 3 transitions from physical boundaries to digital boundaries by examining geofences, a location-based notification service. Interaction between users and multiple geofences are investigated when the configuration of geofences differs (i.e. disconnected, partially overlapping, and completely overlapping) and when geofences are independent or dependent (a rule states that the activation of geofence Y depends on users having visited geofence X). A geofence system is prototyped in an iOS environment and used to further evaluate user-geofence interactions. Chapter 4 expands on the topic of location- based notification regions by investigating what is required for a geofence system to handle events. How changes in conditions (e.g. the spreading of a flood or movement of a fire) interact with geofences and users and what new categories of interactions are required to handle these changes are discussed. The proposed system is applied to a scenario of flooding on multiple rivers interrupting the transportation network.