Reconstructing tree crowns from laser scanner data in forest inventory


Ulla Pyysalo, Petri Rönnholm, Hannu Hyyppä, Henrik Haggrén



In this study, an attempt is to reconstruct ground surface, tree crowns and to use the obtained tree crown vector model for feature extraction. Evaluation of the reconstruction is utilized taking side view photographs from test trees. Photographs are rectified to surface and canopy dimensions are measured for reference data.

   

Reconstruction is carried out in several steps:

1.    Digital surface and terrain models are created from laser scanner data.
2.    Points from single trees are separated from the data set.
3.    Lower limit of the crown is examined.
4.    Ground points are classified.
5.    Vector polygons are formed around tree crown.
6.    Estimation for the location of the trunk is calculated.

Features extracted were: tree height, crown height and location of the trunk.