Reflectance 6. 
% 
20 + 
15 + yu 
0 + Pe 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
400 áo e Foo eoo Jo am 
Fig. 5. 
the reference panels show systematic deviations. Neither boarder effects 
due to great contrast differences in the picture have been noticed, nor 
spectral deviations in the grey wedge used to set up the transfer functions. 
A possible explanation is small differences in look angles between the 
radiometer and the location on the film, which may be significant if there 
are differences in specular reflection. The reference panels were 10 m x 
10 m painted tarpaulins. Due to the huge size of each reference panel it 
was not suitable to use more than three. 
In practise, we are interested in deviations of spectral signatures bet- 
ween areas with the same plant community or trees of the same specie, age 
etc. Hence, it is possible to normalize the spectral signature to an 
arbitrary object.