Fig. 5From: Forest in situ observations using unmanned aerial vehicle as an alternative of terrestrial measurementsExamples of trees captured in the ULS point clouds. a) A Scots pine tree standing in an easy plot; the stem is visible for the most of its length. b) A Norway spruce from an easy plot, lower part of the stem is well visible, while the foliage occludes the upper part of the stem. c) A Norway spruce from a difficult plot, the tree’s own crown, surrounding canopies and understory occlude the entire stem. d) A Norway spruce from a medium plot. The upper part of the stem is identifiable, while lower part of the stem is mostly occludedBack to article page