Automatic reconstruction of single trees from terrestrial laser scanner data

The investigation of single trees in a forest is of ecological and economical interest. One aim is to capture the geometric aspects of a tree: the length and diameter of the trunk and individual branches, the change of the radius along the branch and similar measures. These measures can be determined automatically from terrestrial laser scanner data. The conditions for scanning in the forest, but also the irregular structure and surface of trees aggravate the reconstruction process. The branches of the trees are locally modelled by circular cylinders. With the radius, the axis direction and the axis position the main parameters of interest are captured. We describe a set of algorithms for automatically tting and tracking cylinders along branches and reconstructing the entire tree. Especially for coniferous trees the computation of an outer hull, giving the extent in different directions and at different heights is an alternative, as the dense foliage coverage renders a distinction between branches and needles impossible. Examples for the different reconstructions of trees are presented.