Dorffner, Lionel 
  
  
  
  
  
  
Figure 3. measured breaklines and Arabian strokes 
Next, the different stereo-models were fitted together resulting in a 3D data set consisting of points and line 
information. This data set was then triangulated to build the 3D model consisting of about 12000 surface patches. Based 
on this model a photo-model and digital orthophotos of the dome were produced. Therefore the P31 photographs were 
scanned at the Zeiss PhotoScan PS1. The photographs taken from the floor were scanned with a resolution of 15 
microns and the photographs taken from the scaffold with a resolution of 30 microns, which in both cases corresponds 
approximately to 0.5 cm on the surface of the dome. 
Whereas the interior orientations had of course to be re-measured for the scanned images the exterior orientations were 
taken from the stereo models of the analytical plotter. The 3D model was then projected back into the digital images 
using a rough model of the scaffold to estimate image areas occluded by the scaffold (Figure 4). Nevertheless some 
interactive rework had to be done to eliminate points in fact not visible. Back projection and interactive rework was 
done using the photogrammetric plotting software ORPHEUS [Kager H., Rottensteiner F., 2000], developed at the 
Institute of Photogrammetry and Remote Sensing in Vienna. 
iii Photo 124 
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Figure 4. left: photograph taken from the floor with scaffold as viewing obstacle 
right: part of the dome hidden by one pillar of the scaffold 
  
176 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part BS. Amsterdam 2000. 
      
  
  
  
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