ind 
"a, 
TM 
  
     
BRTID RRNEE/MEDIRN ) 8.4 - 8 IF REJECTED 
RADIODKETER UNITS 
  
  
1 . WAVELENGTH (NN) 
i i 
uaa, SHA. EH. 788. ama. 
DHTE: 758783 RRER: IS 
Fig. 2. Example of irradiance and radiance raw data. Pasture at Ultuna. 
reflectance is based on a set of measurements. This set usually consists 
of measurements of irradiance before and after measurements of radiance. 
Irradiance at the time of each radiance measurement is the estimated by 
linear interpolation between the mean values of the two measurement series 
of the incident light. Measurements have also been made from a helicopter. 
In fig. 2 examples of raw data is shown. The curves include some systematic 
errors which are compensated by calibration. Due to the dynamic range of 
the instrument the diagram has a logaritmic ordinata. Resulting spectral 
reflectance curve is shown in fig. 3. In this case the logaritmic ordinata 
will facilitate the understanding of the visible impression of the object 
and the photographic rendition. 
Processing of the data has been made on a desk top mini-computer (Hewlett 
Packard 9830), which is able to read the Hp 9810 data tape cassetts. 
Calibration of the instrument 
The transmitting diffusing disc have been calibrated in open air 
a Lambertian surface with known directional reflectance. The measurement