Requirements for Modern Geographic Information Systems

In this paper we describe some requirements which an ideal geographic information system (GIS) must meet to cope with the challenges of the future. We look at data modelling, the integration of geographic information science and photogrammetry, update and refinement of a geospatial database, and data integration. We claim that data modelling needs to be carried out in 3D based on a topologic data structure with the possibility for incorporating change. Photogrammetric operations such as the generation of digital terrain models or the manual and automatic acquisition of vector data from imagery should be considered as modules of future GIS, which should also have efficient mechanisms for incremental updating and versioning. Finally, the integration of all types of data should be possible, e.g. various vector data sets as well as DTMs and images. We illustrate the requirements with the help of three examples, one describing data acquisition and modelling in an interdisciplinary project, one dealing with quality control and update using imagery, and the last one presenting an algorithm for the integration of a 2D data set and a DTM. While we believe that the discussed requirements are vital for the development of GIS we are aware of the fact that other issues such as database design, visualisation, and geospatial infrastructure not discussed in this paper, are of similar importance for the field.