natural resource surveys and large scale photos constitute the last level 
of remote sensing data before ground examinations, an accurate method to 
determine scale is required. | 
Westby and others (1968) developed and used operationally a radar 
altimeter in Canada and Surinam. The altimeter penetrates foliage and 
records altitude above ground directly on each exposure. The main draw- 
back to the equipment is the size and bulkiness of the dish antenna (about 
one m) suspended below the aircraft. There is a need for an altimeter 
(radar, laser or sonic) which can be mounted in small aircraft which has 
the capabilities outlined above. 
Declassification of military sensors and systems 
About 1964, thermal and multispectral scanners were declassified by eo e 
the U.S. Department of Defense to allow civilian use, provided that fairly 
coarse resolution requirements (3 milliradians and 19C) were met. In 
1971, some SLAR systems were also declassified.  Considerable impetus to 
the advancement of remote sensing technology resulted when these systems 
were released to the civilian community. 
There are many natural resource users who would benefit if additional 
relaxations were made of sensor and computer processing technology by the 
military. Automatic map making, such as auto-correlative orthophoto ma- 
chines, improved scanners, improved SLAR and laser technology are examples 
of sensors and equipment that would help the user community. Access to 
advanced computer technology and availability of network computer services 
could reduce the cost and improve efficiency of computer assisted clas- 
sification of MSS data. 
The high quality panoramic camera systems being used from satellites 
by both the U.S. and Russian military intelligence agencies could provide 
natural resource managers with inexpensive high quality photography (Green- 
wood, 1973). Some provisions would have to be made to allow release of 
photos to resource managers only within the boundaries of their own country. 
Interpretation o f data 
Low-cost plotting equipment 
There is a great need for flexible, low cost equipment which will 
allow rapid plotting of interpretation results from vertical aerial photo- 
graphs to a planimetric map base. Such equipment should be capable of 
plotting from both paper prints and transparencies, and should accept a 
variety of formats (from 70mm to 23 to 23cm) and a wide range of focal 
lengths. 
Many interpreters produce delineations directly on photos or on 
photo overlays as the result of their interpretations. Particularly in 
mountainous regions, where considerable scale differences and relief dis- 
placements are encountered, those delineations are not true planimetric 
map representations of ground conditions. Therefore plotting must be 
performed before areas can be measured or true ground positions deter- 
mined. There are numerous plotting instruments currently on the market, 
Spanning a wide range of cost and sophistication, however, none possess E 
the flexibility described above at a cost low enough to make them readily v 
available to the majority of persons who could make good use of them.