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Fig. 2 Mapscale vs. contour interval 
T "1:31 Vv1T1 T 
— 
Fig. 3 Mapscale vs. production rates 
— 
A number of explanations can be offered for the large spreads evident in all 
three graphs. In the first instance, these ratios are also influenced by other 
parameters. As an example, the ratio between mapscale and contour interval is 
obviously also a function of the terrain slope. It is therefore clear that a 
much larger sample is required if the effects of the various influencing para- 
meters are to be isolated. Furthermore, and this applies particularly to the 
production rates, a number of the figures extracted from the enquiry are 
questionable and require further verification. 
In conclusion, these large spreads are certainly indicative of the urgent 
necessity to develop and implement systematic procedures for planning photo- 
grammetric projects since, to give an example, the variation in photo scales 
for a given map scale by more than a factor 4 cannot only be justified by the 
various uses of a particular map scale. 
Acknowledgement 
I am greatly indebted to Mr. J. Kure who collected and ordered the material 
included in this report and who also had a considerable role in preparing the 
final draft. 
A.J. van der Weele 
T scale 
NTI sc