The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
91 
Figure 2. The reference block and control points distribution 
The availability of good control points is a crucial requirement 
for in-situ calibration. The control points were derived from the 
LiDAR point cloud using LiDAR intensity as a tool for point 
identification, since no conventional control points were 
available in this project. An example for derived control point 
in the CIR image and in LiDAR intensity image can be seen in 
Figure 3. The expected root means square error of LiDAR 
points is abouti 10 cm all component (Csanyi and Toth, 2007). 
(a) (b) 
Figure 3. The derived control points from the LiDAR point 
cloud in CIR image (a) and intensity image (b) 
The block was flown in approximately 650 m above ground, 
corresponding to an image scale 25300 and the height to base 
relation is about 10 for an average endlap of 68%. In other 
words, the 17.5° view angle in the flight direction with is very 
small comparing to the normal analog camera, which is 73.9° at 
the 153 mm focal length. The small view angle in the flight 
direction requires more images in the flight lines, but more 
importantly, it significantly reduces the Z accuracy of the 
determined object points. 
The different sets of the system calibration parameters were 
computed to analyze the estimated system calibration 
parameters using the BLUH bundle block adjustment software 
from the University of Hannover. The various combinations of 
the adjustment runs with different parameters and results are 
given in Table 1. The focal length f = 25.966 from the 
USGS/EROS calibration report was used as initial value in 
Fable 1 for first two approaches. The twelve additional 
parameters were introduced to block adjustment in the second 
approach (Jacobsen, 2006). The radial symmetric lens 
distortions and systematic image errors are determined with 
additional parameters introduced into the block adjustment. The 
radial systematic lens distortions from both the USGS/EROS 
calibration report and the bundle block adjustment are shown in 
Figure 4 and Figure 5. The systematic image errors of the 
Redlake MS 4100 digital camera were also determined with 
introduced additional parameters as shown in Figure 6. 
Approach 
[pm] 
RMS at 
Control Points 
[m] 
X 
Y 
z 
1 
Bundle block adjustment 
5.5 
0.3 
3 
0.3 
3 
1.2 
8 
2 
Bundle block adjustment 
with 12 add parameters 
4.3 
0.3 
1 
0.2 
3 
0.2 
5 
3 
GPS supported bundle 
block adjustment with 13 
additional parameters 
5.2 
0.3 
3 
0.2 
3 
0.5 
1 
4 
Bundle block adjustment 
with improved image 
coordinate and focal length 
4.3 
0.3 
1 
0.2 
3 
0.2 
4 
5 
GPS supported bundle 
block adjustment with improved 
image coordinate and focal length 
5.4 
0.3 
4 
0.2 
3 
0.5 
5 
Table 1. Reference bundle block adjustment results in UTM 
The correction for the focal length was 123 pm with introduced 
additional parameter to the bundle block adjustment in third 
approach. The affine model deformation of UTM system in this 
test area was causing a 10 pm correction for the focal length 
(Yastikli et al., 2005). The remaining part of the correction for 
the focal length could be explained by the effect of actual flight 
condition such as air pressure and temperature. The additional 
parameters for the location of principle point were not 
introduced to the adjustment because the strips, which were 
flown in twice in opposite directions, were not available in the 
reference block. The corrected focal length, however, resulted 
in improved image coordinates, including new radial symmetric 
lens distortions and symmetric image errors. The traditional 
bundle block adjustment and GPS supported bundle block 
adjustments were repeated with the improved image coordinates 
and corrected focal length in approaches 4 and 5. 
R [mm] 
RedLake MS4100-RGB USGS 
ReaLake MS4100 CIR IN-SITU 
Figure 4. The radial systematic lens distortion from calibration 
report and reference block adjustment