International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
s 1st degree 2nd degree QuickBird Ikonos
# of GCP RMS(m) RMS(m) 2 of 1° 3nd 1° 2nd
10 8.69 degree | degree | degree | degree
Ik 2 2
ones 24 8.16 4.28 Gc? trans. | trans. | trans. | trans.
: 10 7.65 GPS 9 13.04 - 17.603
kBi
QuickBira 24 741 5.18 I8 | 13.778 | 14.137 | 16.216 | 7.682
Hand-GPS 9 11.114 - 16.685 -
Table 4. RMS errors calculated by orthophotos 18 11.873 | 29.744 | 20.597 | 2.128
Orthophoto 10 18.002 - 20.288 -
After the rectification process, geometric accuracy of images 24 21.531 |. 64.460 1.27.29] | 32.119
was tested with ground truth measurements as areal extent and
length. Manually digitized area and length measurements in two
images were compared with the ones measured in field. As a
length, a refuge in the middle of the road was selected; as an
areal extent, a triangle established in the map of Tepekent
residence site and its areal extent was calculated by AutoCAD
software (Figure 4). The actual values of lenth and areal extent
are 502.49 m and 932.343 m.
Figure 4. Selected test areas in QuickBird image (left side) and
Ikonos image (right side).
The comparison was carried out according to the number of
GCPs and order of transformation and outlined in Table 5, 6.
QuickBird Ikonos
1° 3nd 1% nd
# of
degree | degree | degree | degree
GCP "
trans. trans. trans. trans.
GPS 9 0.51 - -6.26 -
18 1,35 -0.48 -6.58 -4.08
Hand-GPS 9 -6.73 - -4.71 -
18 0.47 0.10 -5.29 2.66
Orthophoto 10 1.19 - -2.00 -
24 2.7] -1.78 -4.82 -0.94
Table 5. The errors (meter) from the measured lengths in the
images rectified using GPS, Orthophoto and Hand-GPS.
Table 6. The errors (square meter) from the measured areas in
the images rectified using GPS, Orthophoto and Hand-GPS.
In the results of investigations, it was clearly seen in tables, the
most correct result of length measurements was determined in
the QuickBird image, which was rectified using 1/5000 scaled
orthophotos with 24 GCPs and 2" transformation degree. In the
comparisons of areal extent, the most correct result was found
from the Ikonos image, which was rectified using orthophotos
with 24 GCPs and 2™ transformation degree. From the results
obtained that best accuracy was found applying 2" degree
transformation to these high-resolution images.
3. CONCLUSION
[n recent years Remote Sensing of Urban areas is getting more
realistic and promising application field driven by the
emergence of VHR images for general use (Ulubay et.al, 2003).
The accuracy and interpretability of VHR data such as Ikonos
and QuickBird image make it ideal data for planning and
management efforts and help city managers in planning new
development and developing urban growth studies (Maktav
et.al, 2002).
In this study, the geometric accuracy of VHR images has been
tested with 2D transformation by using GCPs collected in
different ways and comparisons between ground truth data and
the measured length and areal extent in the rectified images
were performed. From the comparison results, it was seen that
the 2D polynomial nonparametric models gave reasonable
results and the geometric accuracy of high-resolution satellite
images is very satisfactory and this leads to conclusion that they
can be used in land use mapping efficiently. It also shows that
VHR images continue to provide more valuable and cost-
effective spatial information that could help planning
development in urban areas.
REFERENCES
Dial, G.; Grodecki, J., 2003. Applications Of Ikonos Imagery,
ASPRS Annual Conference, Anchorage, Alaska, May 2003.
Fritz, L. W., 1999. High resolution commercial remote sensing
satellites and spatial information
http://www.isprs.org/publications/highlights/highlights0402/frit
z.html (Last accessed 15 April, 2004)
Kritzschmar, E. Heinrich, D., Kiihnen, A.Bóhm, C., 2004.
Application of EO Data for Urban Planning in Mega Cities,
http://earth.esa.int/pub/ESA_DOC/gothenburg/] 405boeh.pdf
(Last accessed 15 April, 2004)
Maktav, D.; Erbek, S. F.; Akgün, H., 2002. Use Of HR Satellite
Data For Monitoring Urban Growth, Third International
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