382
CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
3. CAMERA CALIBRATION
The Camedia has been calibrated in ETH-Ziirich using the
BAAP-software. Because of being a zoom-camera, its
calibration has been done both for maximum wide and
maximum narrow angles.
For the calibration of the camera, 9 images of the test field from
different positions have been used. For wide-angle status of the
camera, 30 of 106 control points and for the narrow-angle status
4 of 90 control points have been selected as tie points.
Narrow-angle
Wide-angle
Number of images
9
9
Number of total points
90
106
Number of tie points
4
30
Number of control points
86
76
Number of Measurements
1432
1806
UNKNOWNS
Exterior Orientation parameters
54 (6*9)
54 (6*9)
Tie point coordinates
12(3*4)
90 (3*30)
Additional parameters
10(1*10)
10(1*10)
Total
76
154
Degree of freedom
1356
1652
Table 1. Characteristics of the adjustment for the wide-angle
status of Olympus Camedia C-4040
At the end of the adjustment, following additional parameters
about calibration has been reached.
llfärawl
♦261 9
♦131 0
0.0
-131 0
-261.9-
close I dR = K1‘R*3 -K2*R-6 -K3*R A 7
MikroMeter(dR)
MiJiMeter(R)
1 .10“—
2.64
3.52 4.40
Figure 6. Radial distortion curve of wide-angle status
SIEJlAl ÏÏSS , s
i close I V| F 5300n T'
♦216.8
♦ 108 4
00
-108 4
-216 8
MikroMeter
vtex-y
tfax-x
x-oxis
MiltMeter(R)
“1
2.64
3 52 4 40
Narrow-angle
Wide-angle
Focal Length
20.700859 mm
7.231573 mm.
Principal Point (xO)
0.135214 mm
0.024380 mm.
Principal Point (yO)
0.163940 mm
-0.053714
mm.
Radial Distortion (Kl)
0.000210
-0.004906
Radial Distortion (K2)
0.000006
0.000080
Radial Distortion (K3)
0.000000
0.000001
Decentric Distortion (PI)
0.000116
0.000051
Decentric Distortion (P2)
0.000109
-0.000069
Affinity (Bl)
0.000041
0.000160
Shear (B2)
0.000028
0.000031
Table 2. Camera parameters after adjustment
Figure 5, 6 and 7 illustrate the distortions in different
visualisation types.
Figure 7. Total distortion curves along predefined directions
(red: x-axis; green: y-axis)
4. CONCLUSION
The shown technology has benefits especially in areas, where
restrictions in aerial flights exist. The fast availability of the
data is also a good advantage. The construction of the platform
is modified to get a better stabilization of the rotation but there
will be still a big sensitivity for wind. The result is really fine
but the big number of photos force big work in the data
processing. On the other hand the price for the system, the
balloon and the running costs are relatively small. This
technology has a specific focus, which opens an interesting
market.
Acknowledgements
Authors wish to thank to Mr. Devrim AKCA from ETH-Ziirich
for his support on the camera calibration.
5. REFERENCES
Kemper, G., Celikoyan, T.M., Altan, M.O. and Toz, G. 2003,
Balloon-photogrammetry for cultural heritage, in: 4 th
International Symposium Remote Sensing of Urban Areas, 27-
29 June 2003, Regensburg, Germany
Leloglu, U.M., Tunali, E.and Algun, O., Aerial Photos,
http://vega.bilten.metu.edu.tr/aerialphoto/, (accessed on 12 June
2003)
Figure 5. Distortion of wide-angle status (red: current distorted
image, blue: ideal undistorted image)
