Viewer-based directional querying for mobile applications

With the steady and fast advancements in the integration of geographic information systems and mobile location-based services, interest in exploiting this technology for cultural heritage (CH) data sharing has become apparent. In this area there has been an increasing need to integrate positional information with non-positional data and add a spatial dimension to the definition of a users "context". In this paper, we describe an implementation of a viewer-based directional query processor that operates on an Oracle spatial database. The spatial position and orientation are taken from the viewer's perspective. Using this frame of reference a view-port is defined in real time as the viewer progresses through the space and used as the primary filter to query an R-tree spatial index. Finally, an experimental implementation shows how the query processor performs within a VRML model of Dublin linked to a spatially enabled CH dataset.