3. Basic plotting scales and the corresponding scales of aerial photograph and accuracy 
specifications. 
In the questionnaire prepared by Commission IV one of the questions referred to the 
“tolerance in planimetry” and “tolerance in altimetry”. National reporters interpreted 
the meaning of the word “tolerance” in various ways and in some cases it is difficult to 
say whether answers to these points are to be interpreted as the maximum or mean 
square errors. To avoid misinterpretation on our side, the accuracy specifications are listed 
in the form obtained. 
In addition, the table below gives a review of the scales of aerial photographs used in 
small scale mapping operations in different countries. It is obvious from this table, that 
planimetric content is distinctly the limiting factor as far as the flying height is con 
cerned. With todays facilities it would be possible to fly higher to satisfy accuracy require 
ments. However, the proper photographic definition of small but cartographically im 
portant details requires that the flying height not exeed a certain limit. This is especially 
the case in highly developed countries. 
4. Average time and cost of mapping. 
Time and cost of mapping depends upon so many varying factors that it may appear 
pointless to present statistical figures without explaining all circumstances and general 
conditions. It was felt, however, that the value of such a summary of information lies in 
the relatively large amount of statistical data available and in a certain reliability pos 
sessed by the average quantities derived.