1. Department of Forest Sciences, University of Helsinki, 00014 Helsinki, Finland
2. Department of Geographical and Historical Studies, University of Eastern Finland, 80101 Joensuu, Finland
3. Department of Remote Sensing and Photogrammetry, Finnish Geospatial Research Institute, 02150 Espoo, Finland
4. Department of Built Environment, School of Engineering, Aalto University, P.O. Box 11000, 00076 Aalto, Finland