Especially, in the proximity of the buildings, this situation
causes interference in the segmentation phase. In the first step,
classes were assigned and the convenient criteria were selected
to include the segment in those classes. Results of the
classification procedure are shown in Fig. 4.
re ) S ^
T E i y
A eM
| cost
road
buildings white rocf
e se:
$9 rubbish, area
Q non dassified
Figure 4. Result of object-oriented classification
Regarding the results gained from the created class hierarchy,
most of the buildings and roads could be identified. However,
manual revision of the classification could not be avoided and
the objects that are misclassified with buildings and roads
should be manually erased from these classes. Classification
quality seems strongly depends on the quality of the initial
segmentation and the DEM information used in the generation
of pan-sharpened image. In this case, the geometrical shift and
noise of DEM data used should be taken into consideration.
Based on the classification results, eCognition software can
produce statistical information for the users. Table has an
emphasis because of it shows the error matrix in addition to the
different accuracy values. Kappa of 0.84 shows the results suits
with the expectation, however, for more reliable results suitable
vector layers can be additionally be used.
5. CONCLUSIONS
Because of its high spatial resolution, Ikonos data is well suited
to extract buildings and roads. To take advantage of its spectral
properties, principal component image enhancement method
can be used. In this case, image with 1m ground pixel size, but
covering four spectral channels can be generated. It was seen
that object-oriented analysis technique can reveal satisfied
result for extracting the main land objects, e.g. roads and
buildings.
6. REFERENCES
Benz, U. C., Hofmann, P., Willhauck, G., Lingenfelder, I. and
Heynen, M. 2003. Multi-resolution, object-oriented fuzzy
analysis of remote sensing data for GIS-ready information,
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B3. Istanbul 2004
ISPRS Journal of Photogrammetry & Remote Sensing, 58
(2004) pp. 239-258
Buyuksalih, G., Kocak, G., Oruc, M., Akcin, H. and Jacopsen,
K. 2003. Handling of Ikonos Images from Orientation Up to
DEM Generation. Proceeding of the Workshop on Mapping
from Space 2003, Hannover, (on CD-ROM)
^
eCognition User Guide 3. 2003. Definiens Imaging, pp.3.2-108
Hofmann, P., 2001a. Detecting buildings and roads from
IKONOS data using additional elevation information. In: GIS
Geo-Information-System, 6/2001.
Hofmann, P., 2001b. Detecting informal settlements from
IKONOS image data using methods of object oriented image
analysis - an example from Cape Town (South Africa). In:
Jürgens, Carsten (Editor): Remote Sensing of Urban Areas
Fernerkundung in urbanen Räumen. (-Regensburger
Geographische Schriften, Heft 35), Regensburg.
Hofmann, P., 2001c, Detecting urban features from IKONOS
data using an object-oriented approach. In: RSPS 2001,
Geomatics, Earth Observation and the Information Society,
2001
7. ACKNOWLEDGEMENTS
Parts of the presented results have been supported by
TUBITAK, Turkey and the Jülich Research Centre, Germany.
The authors wish to thank Serkan KARAKIS for his help during
this study.
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