use the same interior and exterior orientation as related 
cameras. The necessary values are obtained from bundle 
adjustment. This step can be performed using any rendering 
or raytracing software that offers "spotlights" (directed light 
source) for image projection. The result of this step is a 
textured 3D computer model of the object ("photomodel") 
from which all requested results can be derived later on. 
4. RESULTS 
The overall photogrammetric restitution took 4 years until 
now and included analytical methods (analytical plotter) as 
well as digital photogrammetric systems. The combination of 
and comparison between can be very well shown in this large 
project. 
Until now over 200.000 single points have been measured 
and calculated to give a very high detailed 3D representation 
of this very complex landmark. Figure 4 shows the level of 
details that have been reconstructed. To give an idea about 
the regional situation also the rock on which the fortress is 
situated and its network of paths has been reconstructed with 
close range photogrammetric means. 
Figure 5 shows the whole model and the still existing gaps 
that are still under reconstruction. 
The work is still in progress and deals at the moment with 
photo texturing of the facades as described in chapter 3. 
The 3D data will be administered in structured information 
systems that do not prescribe or restrict their further use. 
Plans and maps, perspective views or profiles and even 
virtual reality animations are examples of derivative products 
of a coherent database of the object surveyed. The way of 
using the derived data is not limited by this database. The 
kind of presentation will depend on the end user requirements 
and the specific application at hand 
The problems of data fusion, the restitution of such a big 
amount of data, the complex data structure as well as the 
different methods used for restitution and representation 
could be demonstrated. Fly-overs and walk-throughs show 
the detailed reconstruction and the usefulness of 3D 
representation and modelling of monuments and sites of our 
heritage. 
The specific 3D model will be used for interactive navigation 
on the Website of the fortress as well as a stand alone project 
for tourists within the fortress area. So not only it is possible 
to visit the site using the internet but also to give older and 
handicapped people the opportunity to walk around the hilly 
fortress area without having problems. 
  
Fig. 4: Level of detail of the reconstruction (without texture) 
  
Figure 5: Overall view of the 3D model (without texture) 
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