Digital image processing techniques open the opportunity to accelerate the 
architectural photogrammetric process and to relieve the operator from a lot of 
tedious tasks. Therefore he can concentrate on the interpretation of the 
features on the building. Beside this semi-automatic measurement tools another 
field of attention is the development towards an automatic recognition technique 
for selected objects in digital images. The use of special feature extraction 
algorithms and the development of interpretation models for this purpose are 
briefly discussed. Based on advanced image processing techniques, some 
intermediate results for the recognition of stones will be presented.