You are using an outdated browser that does not fully support the intranda viewer.
As a result, some pages may not be displayed correctly.

We recommend you use one of the following browsers:

Full text

International cooperation and technology transfer
Mussio, Luigi

Acquisition of Topographic Data by Laser Scanning and Digital Photogrammetry
Karl Kraus
Institute of Photogrammetry and Remote Sensing
Vienna University of Technology
Vienna, Austria
e-mail: kk@ipf.tuwien.ac.at
Extended Abstract
Data from air-borne laser scanners provide the chance of accurate digital terrain modelling (DTM) in
forested areas. With the use of airborne laser scanners dense point sets can be provided with a vertical
accuracy of about ±0.25cm in flat terrain. Depending on the system used, the horizontal linear point
distances vary from 0.3m to 2.5m. In wooded areas a large portion of the points is not on the ground
surface. These points lie much higher, as the laser beam can be reflected in the tree tops. These are the
so-called vegetation points. To find the real ground surface an interpolation technique for this
asymmetrical error distribution is required.
For this task we proposed to use the well-known linear prediction combined with robust estimation.
With this special filtering and interpolation method an automatic classification of the laser points into
terrain and vegetation points is possible. The experiences made up to now show, that this method can
be used even for a penetration rate of about 25%, if the vegetation and terrain points are mixed
In the future we will concentrate on the modelling of the surface through the tree tops. This surface
can be brought into relation with the terrain surface. The volume between these two surfaces is of
importance in forestry. For this aim laser scanner data recorded with first and last impulse are of
special interest.
The derived contours of a laser scanner DTM are poor in geomorphological detail. Further research
and developments are necessary to find the right combination of laser scanner data and other data
sources, especially digital photogrammetry. The result will be a high quality DTM for large scale
K. Kraus, N.Pfeifer: Determination of Terrain Models in Wooded Areas with Airborne Laser Scanner
Data. Photogrammetry and Remote Sensing, 53 (1998), pp. 193-203.
N. Pfeifer, K. Kraus: Restitution of Airborne Laser Scanner Data in Wooded Area. Geo-Information-
Systems, 2 (1999), pp. 18-21.