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15. 
The systems for the automation of the photogrammetric data re- 
gistration has been further developed during the period. The 
speed of the registration has been increased so that continuous 
registration of the model coordinates is possible today, pro- 
vided that the data are registered on a magnetic tape. The re- 
gistering interval at continuous registration may consist of 
distance - or time interval. As an example of such registering 
devices may be mentioned Wild Ek 8 see fig 8, Zeiss Ecomat 11, 
Cradicon, Ferranti, Wanq and S.F.O.M. This development is also 
important for the introduction of digital terrain model and of 
the automated mapping technique. 
In different countries where the application of photogrammetry 
to Highway Design has been introduced, attention has been paid 
to forming specifications for the photogrammetric accuracy. 
Existing specifications for conventional photogrammetric mapping 
are generally used but as the specifications should be fitted 
to the different stages of design, Separate specifications for 
the photogrammetric quality are required for the application 
in Highway Design. An interesting summary of the U.S. specifi- 
cations for measuring and mapping photogrammetrically was pre- 
sented by William T Pryor, Washington, at the Eleventh Annual 
Photogrammetry short course of the University of Illinois, May- 
June 1971. See (23). Reference is also made to Austin (5) and 
Parkes (20). 
Ternryd, Sweden, has in a thesis (26): "Some Theoretical and 
Practical Aspects Concerning the Problems of Geometrical Quali- 
ty in the Application of Photogrammetry to Highway Design", 
made an attempt to analyse the real needs of geometrical quali- 
ty in the data for the different stages of the Highway Design 
instead of discussing the quality that is attainable. 
It is, however, somewhat difficult getting the designer and 
constructor to present their real requirements. It should be 
observed that specifications requiring a quality that is higher 
than needed always leads into a bad economy.