Paolo Gamba 
  
  
Figure 5. Data over a residential area in Parma, before and after object extraction. 
4 CONCLUSIONS 
The above presented results show that natural and artificial structures are differently treated by the proposed algorithm. 
In fact, even if not based on particular assumptions about object shapes, the similarity concept provides a powerful 
mean to discriminate between buildings and vegetation. This possibility, clearly susceptible of further refinements, may 
be useful for many different applications, like some kind of support to classification algorithms and to the procedures 
for Digital Terrain Models (DTMs) generation. Indeed, DTM characterization starting from range data is one of the 
more interesting open research topics, and this algorithm may provide some hints on how to define adaptive filtering 
techniques suitable for discarding equally well buildings and trees. 
More in general, the aim of this work was to prove that even when no additional information on a site is available, and 
only range data could be considered, model-independent algorithms may provide useful (and, sometimes, enough) 
information to understand the environment. 
We do not pretend that this and similar algorithms are able to analyze completely this kind of data sets, and believe that 
data fusion, i. e. the use of many different sources of data, is the right way to characterize complex environments like 
towns and cities. However, the effort to extract as much as possible from any single sensor's data may be helpful to this 
wider process. 
ACKNOWLEDGMENTS 
We are grateful to the Italian National Research Project entitled Digital surface modelling by laser scanning and GPS 
for 3D city models and digital ortophoto, financed by the Italian Ministry of the University for the 1998 year, and 
chaired by the prof. Galetto of the University of Pavia for providing the data over Parma and Pavia. The research 
presented in this paper was funded by the University of Pavia under the "Progetti d' Ateneo" project. 
REFERENCES 
Gamba P., Houshmand B., 1999, Three-dimensional urban characterization by means of IFSAR measurements, Proc. of 
the 1999 IEEE International Geoscience and Remote Sensing Symposium (IGARSS’99), Vol. V, pp. 2401-2403, 
Hamburg, Germany. 
Gamba P., Houshmand B., Saccani M., 2000. Detection and extraction of buildings from interferometric SAR data, 
IEEE Transactions on Geoscience and Remote Sensing, Vol. 38, n. 1, pp. 611-618. 
  
318 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000.