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81 
The models are to be measured beyond the limits of the quadrilateral of pass points, 
up to a distance of 1 cm from the respective borders of the picture. The plotting of 
every stereoscopic pair involves: 
a. Determination of machine-coordinates and elevations of signalized points in two 
runs; in the second run the points shall be determined in reverse order with 
respect to the first run. 
b. One lecture of machine-coordinates and elevations of unsignalized points. 
In the plotting records the signalized points are to be marked according to the 
quality of focussing possibility in the plotting instrument, namely: A = excellent, 
B = good, C = bad, D = impossible to focus. 
Based upon the 5 pass points of each model the machine-coordinates are to be trans- 
formed into national coordinates by linear transformation. 
At least one stereoscopic pair of each group is to be evaluated by drafting. The map 
plotting involves the representation of signalized points, of non-signalized points 
especially marked on the enlarged aerial photograph, as well as the ground lines 
indieated therein. For map plotting a stable drafting base has to be used. 
a) One certain stereoscopic pair of each group is to be oriented once with internal 
base and subsequently with external base. In both cases the machine-coordinates 
and elevations of signalized points are to be determined in two runs. 
b) This same stereoscopic pair is to be oriented twice separately by two different 
observers and subsequently plotted as menioned in par. 5a) above. 
The Centres have to make an observation report indicating the method of orienta- 
tion, the residual parallaxes after orientation, and the time required. Copies of the 
plotting records shall be forwarded weekly to the Executive Bureau and the Presi- 
dent of the Commission. 
The plotting operations executed by means of the well known plotting instruments 
manufactured by Wild, Zeiss, and Officine Galileo (Santoni) are distributed among the 
different nations according to Table 1. 
The following Centres are participating in the plotting operations: 
In Switzerland: the Eidgenössische Technische Hochschule, Zürich. 
In Germany: the Technische Hochschule, Stuttgart; 
the Institut für Angewandte Geodäsie, Frankfurt/Main; 
the Zeiss-Aerotopograph Company, Munich. 
In Austria: the Bundesamt für Eich- und Vermessungswesen, Vienna. 
In Italy: the Ente Italiano Rilievi Aerofotogrammetrici (E.I.R.A.), Florence. 
In the Netherlands: the International Training Centre for Aerial Survey. 
In order to solve the problems undertaken in the first working period the Commis- 
sion at their second meeting on May 11 and 12, 1955 in Frankfurt/Main agreed upon 
computation of the following errors: 
A. 
Planimetric accuracy. 
L Mean errors of coordinates resulting from residual errors due to transformation. 
IL. Mean errors of x and y resulting from the differences between terrestrial and 
transformed machine-coordinates of the control points: 
a) for signalized points, separately for 
a) points located within the quadrilateral of pass points, 
f) points located outside the quadrilateral of pass points, 
b) for non-signalized points, separately for the same groups as mentioned under 
2a) above and additionally separated according to 
1) points to be identified clearly, 
2) points to be identified with difficulty.