6 
AN OPERATIONAL CONCEPT FOR MAP DATA ACQUISITION 
The new U. S. aerial mapping and survey system will be one of the 
most complete and sophisticated systems ever developed. It will be able 
to acquire data at great speed which can be used to translate into accurate 
maps and charts. Its work, however, must be planned to take full advantage 
of its mammoth capacity. 
Trilateration networks can be accomplished with our regard to the 
weather. Control Point Photography to satisfy the needs for horizontal 
control, can be acquired with as much as 507, cloud coverage in the area. 
The airborne or terrain profile recorder for elevation profiles are not 
dependent upon the electronic ground stations so this phase of the mission 
can be accomplished when the visual photography is taken. 
This new system will eliminate much of the drudgery and time required 
for acquisition of map control data. However, there is still a huge 
obstacle confronting the aerial mapper. Visual mapping requires cloud free 
areas to complete this phase of the mission. To complicate the problem for 
the aerial mapper, weather reporting is practically non-existent in many 
parts of the world today. 
Needless to say, the business of map making is largely dependent upon 
the acquisition of aerial photography. I would, therefore, like to direct 
your thoughts to the aerial mapper and see how he goes about the business 
of fulfilling this task. 
You may well know that the aerial mapping organizations do not welcome 
jobs in an area where clouds would make it a highly speculative venture. 
Just how does the aerial mapper go about his business of betting on 
enough clear cloudless days to make his profession pay? 
Meteorological records in developed nations have been officially kept 
since 1664. These records provide statistical data of selected areas and 
reports are obtainable which indicate the average number of days per month 
that completely clear skies should prevail. 
For example, in the U. S., Phoenix, Arizona, lists 210 possible photo 
days a year. If all photo projects were in areas such as Arizona, the 
aerial mapper's job would be simple. 
The usual report of expected weather for a certain month indicates that 
in the best photo season you can expect a few clear days suitable for 
aerial photography. These figures are a statistical average and the current 
or succeeding years may or may not repeat the normal average.