offset results for the 
1e combined method 
strip overlap; offset 
d matching over the 
n Table 4. Success 
types of terrain. In 
able. The benefit is 
nediately obvious in 
from both methods 
metric matching de- 
itter example, which 
ion as described in 
' conclusions in the 
Y CONTROL 
the combined geo- 
clouds, is currently 
n workflow. For the 
1ed along the center 
F 1000-5000 pixels. 
ed statistics for all 
ive report. Based on 
rent kind, in parti- 
'ameters that enable 
of reliable offsets 
e overlap as well as 
. of patch footprints 
which allows for an 
are such as Global 
? primary tool used 
The large number of valid patches provided from the automatic 
computation allows for more detailed investigations, e.g. the 
evaluation of individual strip overlaps. This is expected to assist 
not only in the very QC process but also in the general analysis 
of image orientation parameters and aerial triangulation be- 
havior. These new possibilities are discussed and illustrated for 
the Lansing block in Gehrke et al. (2012). 
5. CONCLUSION 
This paper proposed and evaluated an automated approach for 
Shear Analysis of ADS blocks, based on dense image matching 
and combined geometric/radiometric point cloud matching. The 
utilization of the radiometric information from the info clouds 
was demonstrated to be crucial for the purpose of computing 
reliable offsets in-between overlapping ADS image strips for 
two reasons: First, the combined approach is more robust and 
delivers a larger number of offsets for various types of terrain, 
resulting in an approximately even coverage throughout large 
blocks. Second and most important, it delivers more reliable 
results compared to the solely geometric approach, which is 
prone to some errors that cannot be automatically detected. 
With the goal of replacing the current manual QC measure- 
ments of strip-to-strip offsets it is noteworthy that the automated 
approach delivers very similar results with similar or better ac- 
curacy; it improves especially the height component. 
In conclusion, it is shown that the combination of geometric and 
radiometric information is not only beneficial but crucial to pro- 
vide both sufficient and correct input for a meaningful analysis 
of ADS data. Looking beyond current QC requirements, the 
automated Shear Analysis has already shown to be a very useful 
tool for the evaluation of image orientation parameters and their 
impact on geometric product accuracy. 
The combined geometric/radiometric point cloud matching and 
the entire Shear Analysis procedure were implemented for ADS 
but are not limited to it. They can be applied to any type of 
(stereo) imagery. The very point cloud matching should be 
applicable to LiDAR data as well, but this possibility would 
have to be explored. 
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