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AGREEMENTS FOR THE SPECTRAL MEASUREMENTS IN JAPAN 
In Japan, the spectral radiance factor is measured standing upon 
the standard white, where the radiance factor as the reflection 
quantity of the object recomended by CIE, is used. 
At present, the spectral radiometer is under construction and 
the way of the measurement is under way, and the reflectance factor 
will be demonstrated in the future. 
Now, the following items should be written in addition when 
measuring the radiance factor: 
Sun's altitude 
thé azimuth of tbe observation 
the degree and the type of the cloudness 
the instantaneous field of view of the measuring instrument 
the type of the used reflection standard 
the observation time and date 
the degree of the haze (slant visual range) 
the number of the measurements. 
[e WN 
° 
The standard white: Kodak white reflectance paint, which is 
calibrated to a smoked Mgo, will be in 
general use. 
*The accuracy of the measured spectral signature of the certain 
object. 
The measured value of the certain objects in the open-air will 
be greatly influenced with the observation direction, sun altitude, 
and the weather in addition to the accuracy of the spectroradio 
meter. So the accuracy of the measurement will be more high when 
the high accurate instruments are applied, in a short observation 
time(e.g. in a few second or so), and when the measurements are 
repeated. For this purpose, the experiments should be repeated with 
the new high accurate instruments.