Efficient spatial data acquisition in temporal geographic information systems

The large potential of Geographic Information Systems (GIS) still contrasts with the enormous cost of spatial data acquisition and update. With the advent of temporal GIS and the huge volume of spatio-temporal data, the need for efficient spatio-temporal data acquisition methods becomes urgent. The research project described here addresses these issues: a joint luso-german research group set out to create DIGIT, a prototype system for the efficient acquisition of spatio-temporal data. In the DIGIT environment, a collection of scanned maps describing the spatial development of a region over a period of time is kept in a temporal raster map archive. These maps serve as data sources for an integrated automatic vectorization system and as a backdrop for interactive manual digitization. A partial implementation of DIGIT has been integrated into a temporal GIS for historic research and evaluated in an application in the structural development of a part of Coimbra. A summary of DIGIT's innova tive aspects includes a temporal, configurable model for spatial object data, a spatio-temporal object database on top of ORACLE and an interactive environment for the manual digitization of temporal raster data