1. GIScience Center, Department of Geography, University of Zurich, Zurich, Switzerland
2. Research Group Cartography, Department of Geodesy and Geoinformation, TU Wien, Vienna, Austria
3. Research Group Applied Geoinformatics, University of Augsburg, Augsburg, Germany
4. Institute of Cartography and Geoinformation, ETH Zurich, Zurich, Switzerland
5. Department of Geography, Ghent University, Ghent, Belgium