The Editors Michael Goodchild is Professor of Geography and Director of the National Center for Geographic Information and Analysis at the University of California, Santa Barbara, California USA. Louis Steyaert is a Remote Sensing Scientist at the Science Applications Branch, EROS Data Center of the US Geological Survey. Bradley O Parks is an Environmental Scientist with the University of Colorado, Boulder, Cooperative Institute for Research and Environmental Sciences, USA. Carol O Johnston is a Senior Research Associate at the Natural Resources Research Institute of the University of Minnesota, Duluth, USA. David R Maidment is Professor of Civil Engineering at the University of Texas at Austin, USA. Michael P Crane is Director of the Central Region Geographic Information Systems Laboratory of the US Geological Survey. Sandi Glendinning is a Visitor and Program Coordinator for the National Center for Geographic Information and Analysis at the University of California, Santa Barbara, California, USA.