- 670 = 
Hand-held radiometers, as referred to in this report, are some light-weight 
device with various bands configured spectrally by a custom-made interference 
filter for each band (see Pearson, et al., 1976). 
A logical extension of hand-held devices to more sophisticated 6 to 15 band 
instruments could easily be undertaken. This would make available for the 
first time the possibility of a standard ground-based remote sensing device 
which would be easy to operate, accurate, inexpensive, and could be used as 
a 3-band device or as a 6 -15 band truck mounted instrument. Such work is 
currently underway at NASA/GSFC. 
Conclusions 
1. Additional and numerous ground-based remote sensing studies are needed 
immediately to expand our understanding of spectral reflectance from 
vegetation targets. This will not happen quickly if only field spectro- 
meters are used. 
2. Discrete band radiometers, configured by custom-made interference 
filters, have proven tó overcome the limitations of spectrometers. 
Spectrometers are needed, however, to define those wavelength regions 
to be used in the discrete band radiometers. A previous effort in 
these respects is reviewed and documented. 
3. Discrete band radiometers, whether they are hand-held ( £ 6 bands) or 
boom supported (8-15 bands) offer a logical means of expanded remote 
sensing data collection. They are inexpensive and could be standardized 
to facilitate inter-comparisons between different investigators. 
4. The value to any life science discipline when instrumentation becomes 
available that does not require extensive knowledge of physics or 
electronics for operation is great. An example would be the tremendous 
biological advances made possible by the electron microscope when 
biologists (cytologists, anatomists, physiologists, etc.) could operate 
these instruments vis-a-vis the use of them in biological research by 
only physicists. Remote sensing instruments are needed for plant 
Scientists. In this fashion, the potential of remote sensing of 
vegetation will be realized. 
Addendum 
I have attempted to document the development and applications of discrete 
band hand-held radiometers by reviewing the work which led up to this new 
approach. As such, I have only reviewed my/our own work. This was not 
done for egotistical reasons but simply because that was the course of 
events. It should be mentioned that workers at LARS/Purdue have reached 
the same conclusion from their more recent efforts in the collection of 
field spectrometer data (Robinson et al., 1978). I feel any group who takes 
this approach for monitoring vegetation and is successful quickly realizes 
the limitations of field spectrometer data collection. Discrete band