1. a Claudia Kuenzer , Institute of Photogrammetry and Remote Sensing (IPF) , Vienna University of Technology , Gusshausstr. 27‐29, A‐1040 Vienna, Austria
2. b Beijing Normal University, BNU , Beijing 100856, China
3. c German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) , Oberpfaffenhofen, D‐82234 Wessling, Germany