1. a Laboratory of Geo-Information Science and Remote Sensing , Wageningen University , Droevendaalsesteeg 3, 6708, PB Wageningen, the Netherlands
2. b ISRIC – World Soil Information , 6708, PB Wageningen, the Netherlands
3. c Remote Sensing Laboratories , University of Zurich , Winterthurerstrasse 190, CH-8057, Zurich, Switzerland