Neither the goals nor the procedures of 3D mapping are clearly defined yet
(c3) Identification and mapping
of individual map features
For the evaluation of individual map
features like forests, bridges, airports,
power lines, churches etc. the two
cartographic operators used the whole
imaged area of Thun. Some features like
forests, rivers > 2-3 m, fruit orchards,
soccer grounds, a golf course, a camping
ground and a harbor could be identified.
Other features like churches where only
observable in less dense areas or when they had a special, traditional architecture.
Conclusions
We have pointed out that neither
the goals nor the procedures of 3D
mapping are clearly defined yet. The
available new technologies require a
totally fresh approach to mapping.
Satellite images are an interesting source
for 3D mapping. However, they still do
have a number of substantial disadvantages
when compared to aerial images. As
spatial and hopefully also radiometric
resolutions improve in the future their
suitability for landscape model generation
and for medium scale topo-mapping
has to be continuously evaluated.
In our tests with manual mapping from
IKONOS stereo images we found problems
in reproducing small geo-morphological
details in contours, especially in cases of
vegetation covering the bare earth. From
these satellite images less map features
could be interpreted compared to aerial
images, and definitely not with the same
reliability. However, the experienced
topographer, using empirical knowledge,
including also the special characteristics of
the country, found many more features than
we expected. All in all the IKONOS images
were not sufficient for the production of
1:25,000 map data. But even if we consider
that satellite images are already now
available at the same spatial resolution as
aerial images (WorldView-1 with 0.5 m
GSD) we still have to take into account the
lower radiometric quality of satellite data.
Especially digital aerial images provide us
with a hitherto unsurpassed image quality,
which is very crucial when it comes to
the interpretation of map features.
However, these statements refer to the
map specifications of Switzerland. In
other countries these specifications may
not be as stringent.All the previous results
were obtained by manual measurements.
We should clearly understand that we
are currently still very far away from
any reliable procedure of automated
landscape model or map generation. This
remains a key topic for further research.
References • Fraser, C., Dorji, T.,Gruen, A., 2008:
High resolution satellite mapping
for spatial information generation in
Bhutan. Paper accepted for presentation
at the XXIth ISPRS Congress, Beijing,
3-11 July, Commission VI, WG 6.
• Gruen, A., Wolff, K, 2008. 3D mapping
from highresolution satellite images.
Paper accepted for presentation at
the XXIth ISPRS Congress, Beijing,
3-11 July, Commission IV, WG 9.
• Wolff, K, Gruen, A., 2008: Upto-
date DSM generation using
highresolution satellite image data.
Paper accepted for presentation at
the XXIth ISPRS Congress, Beijing,
3-11 July, Theme Session 3.
• Zhang, L., Gruen, A., 2006. Multiimage
matching for DSM generation
from IKONOS imagery. ISPRS Journal
of Photogrammetry and Remote
Sensing, Vol. 60, pp. 195-211.
Prof Dr Armin Gruen
is since 1984 Professor
and Head of the Chair
of Photogrammetry and
Remote Sensing, ETH
Zurich, Switzerland.
He is Member of Editorial Boards of several
scientific journals. He has published more than
350 articles and papers, is Editor and Co-editor
of 20 books and Conference Proceedings and
has organized and co-organized/-chaired
over thirty international conferences.
He is currently Chairman of the ISPRS
International Sientific Advisory Committee
(ISAC). agruen@geod.baug.ethz.ch
Dr Kirsten Wolff is since
2002 a scientific member of
the Chair of Photogrammetry
at the Institute of Geodesy
and Photogrammetry, Federal
Institute of Technology
(ETH) in Zurich, Switzerland. She obtained her
doctorate degree 2007 in Photogrammetry
from the Institute of Photogrammetry and
Remote Sensing, Rheinische-Friedrich-
Wilhelms University Bonn, Germany. wolff@geod.baug.ethz.ch
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