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L. Eysn, M. Hollaus, M. Vetter, W. Mücke, N. Pfeifer, B. Regner:
"Adapting α-shapes for forest delineation using ALS Data";
Talk: 10th International Conference on LiDAR Applications for Assessing Forest Ecosystems (Silvilaser 2010), Freiburg, Germany; 2010-09-14 - 2010-09-17; in: "Silvilaser 2010", (2010), 10 pages.

The objective of this paper is to evaluate a new approach for the automatic delineation of
forested areas based on airborne laser scanning (ALS) and national forest inventory (NFI)
data. In the Austrian NFI a forest area is mainly defined with four fundamental criteria.
One of these criteria, the so called "crown coverage", is the most complex variable and
therefore the main focus of this paper is on defining and implementing this criterion in an
automatic process to delineate forested areas. Based on Austrian NFI data functions were
determined for two different test sites in Austria, describing the criterion crown coverage
as a relation between tree height and the distance between trees. Based on the ALS data
an automatic method on the basis of adapting α-shapes was developed to link these
functions to the ALS data. The approach was tested for two different test sites in Austria.
For the first test site a tree species independent function was applied. The results of the
delineated forest mask are validated with a reference forest mask which was manually
delineated based on orthophotos. The derived forest mask differ less than 1.6% from the
reference forest mask and shows a very high accuracy. For the second test site tree
species dependent functions were applied for the assessment of the crown coverage. The
presented approach shows promising results and shows the high potential for the
automatic forest area delineation based on ALS data.

http://publik.tuwien.ac.at/files/PubDat_194896.pdf