laser points around buildings, often discarded by re- 
searchers, are actually very useful in the process of veri- 
fying hypotheses of objects. For example, points that do 
not seem to belong to a roof nor a ground surface may 
have been reflected from the side of a building. Clearly, 
this would be very useful evidence when we hypothesize 
about buildings and try to reconstruct its shape. We will 
intensify our research effort to detect these “problem- 
atic" points and to take advantage of them in the ob- 
ject recognition process. This will include an attempt to 
better understand the relationship of the laser's return 
signal and the surface it was reflected from. 
5 Acknowledgement 
The laser data sets used in the experiments was made 
available by NASA Goddard Space Flight Center, Wallops 
Flight Facility. We acknowledge the support of William 
Krabill and Serdar Manizade who helped us to process 
the data. The aerial photography was made available by 
the National Geodetic Survey (NGS). We are greateful to 
the generous support by James Lukas and Grady Tuell. 
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