The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B3b. Beijing 2008 
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Figure 15: Buildings do not have a common border anymore. 
5. CONCLUSION 
The research shows that by using the Hough Transformation for 
building extraction we have many advantages, such as the good 
handling of noisy data, the easy adjustment of level of detail of 
the output data, the ability to force certain geometric properties 
into the extracted buildings and the possibility to bridge gaps, 
meaning that building comers that might not be visible in the 
imagery can be determined accurately. The proposed 
methodology proves to have certain weaknesses when dealing 
with radiometrically heterogeneous roofs, when big shadows 
partly cover roofs of the buildings to be extracted, when the 
building geometry becomes very complex, or when the input 
data set comprises many compound building. 
Summing it up, one can conclude that the Hough 
Transformation is a very powerful tool for automated building 
extraction and creation of digital city models, but the degree of 
automation is still highly correlated to the quality of the input 
data. 
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