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L. "Synthetic Stereo" Will be Used to an Ever-Increasing Extent 
as an Aid to the Interpretation of Space Photography. 
The lack of relief displacement in a space photograph is a 
blessing when we wish to have a near-orthophotographic record 
of the landscape. Axiomatically, the lack of relief displacement 
is the very attribute that most limits the interpretability of 
a space photograph when the objective is to identify certain im- 
portant features that are of interest to the managers of natural 
resources. The remedy to this deficiency as applied to terrain 
features that are of sufficient size to be clearly resolvable 
on the space photograph is to be found in a form of "synthetic 
stereo" that can be produced for any area that already has been 
topographically mapped to a suitably small contour interval. The 
technique is fully described in the proceedings of the United 
Nation's Cartographic Conference (1959). 
M. "Shadow Parallax" Also will be Exploited in the Future as a 
Means of Perceiving on Space Photographs the Three-Dimensional 
Characteristics of Features. 
Interest in this technique also stems from the lack of relief dis- 
placement in a space photograph. Depending upon the resolution of 
the space photography the technique can be applied to mountains, 
buildings, or even trees. If two photos are taken of the same 
area, but at different times of day, (e.g., one hour before noon 
and one hour after noon, local sun time) and then viewed through 
a stereoscope the shadows will be seen to have shifted their 
positions. Furthermore, the taller the object the greater the 
shift will have been. As seen through the stereoscope the apparent 
heights of the shadows are indicative of the actual heights of 
the objects casting them. Illustrations of this technique appears 
in the Manual of Photographic Interpretation (American Society 
of Photogrammetry, 1960). 
N. Future Improvements in Sensor Capabilities and Resource 
Classification Schemes will Better Conform to the Requirements 
Imposed by Resource Policy Decisions and Management Objectives. 
In an earlier section of this paper some consideration was given 
as to the kinds of information, both basic and applied, that might 
be desired by those working in various resource-related disciplines. 
In the present section let us build on those considerations by 
acknowledging that either of two approaches might be used as we 
seek to relate remote sensing capabilities to user requirements. 
In the first approach, remote sensing capabilities would be con- 
sidered at the outset and, in the light of these capabilities, an 
exhaustive list would be compiled showing all the kinds of in- 
formation that might be attained through the full exercise of 
these capabilities. Then due consideration would be given to each 
item on the list in order to determine whether that item might 
conceivably satisfy some user's informational requirements. 
In the second approach, a list of economically significant or 
otherwise important user requirements for information would be 
compiled. Once the list had been compiled, consideration would be 
given to the various remote sensing capabilities in an effort to