cameras. If we realize further that tonal rendition in aerial photographs is 
influenced by many other factors such as film processing, atmospheric factors, 
etc., it appears that the knowledge of absolute reflectance values may not be 
a very significant type of information to have. Considering the great complex 
ity of the system I am inclined to favour the posteriori approach to photo 
analysis at this time, i.e. working from "what we have" rather than from 
"what we should have". This is not to say that we should not go on with the 
investigation and study of the reflectance phenomenon. Apart from the appli 
cation that knowledge of reflected energy may or may not have in remote 
sensing, its relation to absorptance makes it a very useful quantity in energy 
budget studies of vegetation. 
ACKNOWLEDGEMENT 
The above work was financed and assisted in other material and 
intangible ways by the Forest Management Institute, Department of the 
Environment, Ottawa.