Environmental processes often vary in space and time and act over several scales. Current software applications dealing with aspects of these processes emphasize properties specific to their domain and tend to neglect other issues. For example, GIS prefers a static view and generally lacks the representation of dynamics, temporal simulation systems emphasize the temporal component but ignore space to a great extent, and virtual reality tends to "forget" the underlying data and models. In order to remedy this situation we present an approach that aims to bring together the three domains; temporal simulation systems, GIS, and virtual reality, and to foster the integration of particular functionalities. This paper concentrates on concepts and requirements for the development of a suitable software architecture using case studies and use cases seen from a GIS-based perspective. (C) 2005 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved.