A unified index structure for efficient enforcement of spatiotemporal authorisations

Abstract

Uncontrolled dissemination of geospatial data may have grave implications on national security and personal privacy. Geospatial data can be considered sensitive based on attributes such as the location, resolution and the time of capture, etc. As such, authorisations associated with this data also possess spatial and temporal attributes. The main contribution of this paper is to improve the response time of access requests, by proposing a unified index structure called *-tree that is capable of indexing both spatiotemporal objects and authorisations in a single index structure. *-tree is an extension of R-tree that indexes objects based on their resolutions as well as on their spatial and temporal attributes and overlays spatiotemporal authorisations on the nodes of the tree. We show how the *-tree can be constructed and maintained, provide algorithms to process access requests and present performance evaluation results that demonstrate a significant improvement in performance.