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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
The differences between the two solutions are well within the 
a'ccuracy specifications of the AEROcontrol system. 
Figure 6 shows the differences between solution A and solution 
C (base station vs. PPP). For the application of the trajectory for 
direct georeferencing, the position differences would have to be 
considered. The most relevant difference is the height 
difference of up to 0.2m. 
297.000 298.000 299.000 300.000 301.000 
[sec] 
f- roll - pitch - yaw [ 
Figure 6: Comparison between solution A and solution C (base 
station vs. PPP). 
The effect of the difference in the GPS solutions to the attitude 
determination is relatively small. The effect in the resulting 
orientation angles would be insignificant for the most direct 
sensor orientation tasks. 
For the introduction of the trajectory information as additional 
measurement into an extended aerial triangulation (Integrated 
Sensor Orientation “ISO”), the effect of the difference between 
the different GPS processing methods would not be significant. 
Max. [mm] / RMS [min| 
ANorth 
AEast 
AUp 
Base vs. VBS 
6.3/1.1 
7.0/2.2 
19.4/4.2 
Base vs. PPP 
37.1 / 12.1 
66.4/38.1 
214.1 / 139.7 
Table 1: Position differences between the different solutions. 
Max. 
mdeg] / RMS [mdeg] 
ARoll 
APitch 
A Yaw 
Base vs. VBS 
<0.1 /<0.1 
<0.1 /<0.1 
0.1 /<0.1 
Base vs. PPP 
0.5/0.1 
0.4/0.1 
1.3/0.6 
Table 2: Attitude differences between the different solutions. 
5. INVESTIGATION OF THE SYSTEM ACCURACY 
The empirical accuracy for the three different flight blocks was 
obtained from comparison at independent check points in object 
space. Their coordinates were re-determined through bundle 
adjustment or direct georeferencing and then compared to their 
a priori known reference coordinates. 
5.1 Quality of reference points test site Vaihingen/Enz 
The reference coordinates have been determined through static 
GPS base line surveys in summer 2007. The whole 
measurement campaign consisted of 7 measurement days within 
a three weeks period of time. Two independent survey groups, 
each using a geodetic GPS receiver, did the base line 
measurements. The GPS reference station observations were 
obtained through SAPOS. A virtual reference station was used 
to keep the base line length as short as possible. To control the 
overall accuracy of base line observations each GPS group has 
done repeated measurements of the same distinct point twice 
each measurement day, in the morning and after finishing their 
daily measurement. Thus overall 28 repeated measurements of 
the same point were delivered from the seven measurement 
days necessary. Their statistical variation is given in Table 3 
and reflects the absolute accuracy of the analysed base line. 
Since the other base lines are of comparable length, the 
obtained accuracy of about 1cm (std.dev.) for horizontal and 
2cm (std.dev.) for vertical coordinates can be transferred to the 
remaining control points. Note that these accuracy numbers also 
include the repeatability (i.e. re-identification of object point for 
each new measurement), besides the pure accuracy from GPS 
survey. For later processing (during the AT runs) the accuracy 
(std.dev.) for control points was assumed to be 0.02m for all 
three coordinates. 
AEast 
ANorth 
AUp 
[m] 
[m] 
fm] 
Std.Dev. 
0.008 
0.009 
0.018 
Max.Diff. 
0.019 
0.018 
0.037 
Min.Diff. 
-0.018 
-0.018 
-0.034 
Table 3: Accuracy of ground control points in Vaihingen/Enz 
test site from static GPS survey. 
5.2 Determination of boresight misalignment 
Direct GPS/IMU exterior orientation (EO) measurements have 
been done by the AEROcontrol-IId integrated system. The 
trajectory solution A (based on the station “0384 Stuttgart”) has 
been used for the later bundle adjustments and direct 
georeferencing. Before those EO parameters can be used for 
direct georeferencing, they have to be related to the two 
individual camera heads of the dual head constellation. 
The boresight angles for both camera heads have been 
determined by comparing the measured GPS/IMU angles with 
the angles of a bundle block adjustment done from the available 
image blocks. In the bundle block adjustment the images from 
both cameras together with the uncalibrated GPS/IMU results 
have been used simultaneously.