4. THE ISPRS TEST AREAS 
  
3 
Drivdalen, Norway. 
Profiles from the test area Drivdalen have been measured by 4 groups: A,B, 
D and E. In figure 3, spectra estimated from profiles measured by A and D 
are shown. The profiles from A were sampled with a point distance of 30 
meters, while the profiles from D were sampled with a spacing of 5 meters. 
The profiles from A,B and D were measured in photos of scale 1:17.000, while 
the profiles from E were measured at scale 1:10.000. 
Lac? (M9 
LaC? (M3) act On 
N 
10? 
10° 2 
10* 
  
  
  
  
  
  
103 
  
  
102 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
WRVELENGTH (M) WAVELENGTH (MD 
Measured by D Measured by A 
Fig. 3. Spectra of Drivdalen, Norway. 
The spectrum of Drivdalen has a rather steep slope between wavelengtn 
100 meters and 1000 meters. This feature can Clearly be seen in Fig. 1. 
Between 100 meters and 10 meters the inclination is somewhat less. From 
A, only the longwave part of the spectrum can be calculated, and because 
this part has a steep inclination, a straight line fit on to the spectrum 
will yield a higher value of a than a line fit on to the lower part of the 
spectrum from D. 
In table 3, the coefficients for the straight line approximations of the 
spectra measured by the 4 participants are listed. The inclination angles 
are smaller for the two spectra calculated from dense profiles, and the 
value of E is greater. This is consistent with the form of the spectra 
discussed in connection with figure 3.