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projects. The Independent Model Triangulation is nearly always used as a standard 
procedure using precision plotters or stereocomparators provided with automatic coor- 
dinate registration for the measurements and the *Anblock" procedure for planimetric 
adjustment. 
111.2. Research 
At the Sub-department of Geodesy of the Delft University of Technology special attention 
is given tot the determination and checking of the weight-matrix of coordinates of points 
measured in a model (112). 
In the context of IMT a method for the determination of the projection centre by means 
of intersection of rays has been studied (110). 
In the period under discussion the main activity of the I'TC was related to an investiga- 
tion into the accuracy of practical photogrammetric triangulations, entrusted to the 
Institute in accordance with a resolution adopted at the Lausanne Congress. The main 
aim of this investigation was to bridge the gap between photogrammetric theory and prac- 
tice by supplying data obtained from daily routine adjustments executed by independent 
agencies, which could be used to calibrate the theoretical investigations. 
In addition to the distribution of questionnaires to mapping agencies throughout the 
world, project data was also collected from reports in scientific journals etc. The pre- 
liminary results of the investigation were presented by Kubik and Kure in a report to the 
Commission III Symposium, held in London in 1971 (101); the final report is being 
prepared for presentation in Ottawa. 
At the same London Symposium, Kubik (100) presented a report on an investigation 
into the effects of various types of simulated systematic image errors on the results of bundle 
strip and block adjustments. This subject is being continued and results will be published 
as they come available. 
A study on the adjustment of APR and statoscope data in the form of a network without 
ground data has been concluded (I'TC publ. A52). 
CHAPTER IV. MAP PRODUCTION 
IV.l. Applications 
The practice of photogrammetric mapping in the Netherlands, as described in foregoing 
national reports, has been continued in the period 1968-1972. In addition several develop- 
ments can be reported. 
IV.1.1. Survey department of Rijkswaterstaat 
Since 1969 a method of digital planimetric mapping has been developed which at present 
is being used for about 10% of the total production. For details of the method we may 
refer to the publications (62,2). A short characteristic is that after a relative orientation of 
a model in a plotter the coordinates of all relevant points are measured and registered on 
tape. These points include ground-control points, connection points with adjacent models 
as well as all detail points forming the map contents. The first mentioned groups of points 
are used for the computation and adjustment of the aerial triangulation (if included in the 
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