Juha Hyyppä
The proposed method is useful especially in sparse mature stands. Difficulties were found especially in dense forests,
where single trees were not easily identified. In dense parts the crown area is usually underestimated, because trees grow
partly interlocked, and in such cases the segmented areas should be corrected, for example, with the calibration model. It
is also obvious that only crowns in the top layer can be detected and the smaller trees underneath remain invisible.
ACKNOWLEDGMENT
The authors are grateful to the European Commission and the Academy of Finland for financing of this study, to Mikko
Lehikoinen and Olavi Kelle from University of Joensuu/Arboreal Oy for providing the initial segmentation software for
the study. The authors want to acknowledge the HIGH-SCAN project partners: Helsinki University of Technology
(Finland), Joanneum Research (Austria), University of Freiburg (Germany), TopoSys GmbH (Germany), Scherrer
Ingenieurbüro AG (Switzerland) and Forestry Development Centre Tapio (Finland).
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