Thursday August 3 1972, 11:20 
Business Session 
Chairman: A.J. van der Weele. 
The Chairman opened the session by stating that 12 Resolutions had been submitted. Ten of these referred to 
topics formerly covered by Commission IV, while two were of a more general nature. The Chairman also 
pointed out that the allocation of these Resolutions to the various Commissions would be done by the ISP 
Resolutions Committee. 
The Resolutions were discussed and approved. 
After thanking the delegates for their co-operation, the Chairman closed the session. 
Friday August 4 1972, 15:45 
Urban Mapping Session 
Chairman: AJ. van der Weele 
Panel Chairman: S.G. Móller 
Panel: B. Dubuisson, H.L. van Gent, R. Fórstner, W.F. Roberts. 
The Chairman welcomed the delegates to this last session of Commission IV, and invited R. Forstner to 
summarize his Invited Paper for this session, entitled, **Basic Maps for Urban Regions". 
The panel Chairman then introduced the panel, and announced that each of them would briefly summarize 
their experience in their own country, before proceeding to the discussion of a number of prepared 
questions. 
H.L. van Gent outlined his experience in the Netherlands, where both topographic maps at the scale of 
1:10,000 and cadastral maps at the scale of 1:1000 are employed. Experiments are presently under way to 
photograph the centre of Amsterdam with both 21 and 60 cm. focal length cameras. Photogrammetry is used 
extensively, field surveys being mainly required for the location of street furniture. 
The panel Chairman then outlined the results of a number of tests carried out in Sweden, where, due to the 
correlation between photogrammetric observations, short distances computed photogrammetrically are more 
accurate than those measured by ground methods. This has resulted in the acceptance of photogrammetric 
methods, but limits have been set for the maximum distances that can be measured photogrammetrically with 
various photo scales. 
B. Dubuisson then gave a brief review of the experience in France, where the usefulness of orthophotomaps 
has been accepted. The activities in urban mapping presently involve the establishment of the geodetic 
framework, the recording of the real estate properties and the road networks, the survey of the progress made 
with the establishment of utilities, and finally the survey of the real estate properties. The experience in 
Northern America was then outlined by W.F. Roberts, who emphasized the necessity of establishing ground 
control networks, basic specifications, and even the creation of a national secretariat on urban mapping. 
The panel Chairman then put the first question to the panel, namely, whether checks exist controlling the 
geometric accuracy, the completeness of the information, and its adequate graphical representation. Although 
Sweden has strict rules on these aspects, it was remarked that it is difficult to establish international standards, 
since, for example, the accuracy depends upon the legislation and the need for the particular product in the 
country concerned. It was therefore considered of importance to collect information on difficulties experienced 
in various countries. 
Opinions differed on the second question, concerning the comparison of the establishment of control networks 
by geodetic or photogrammetric means, some countries not using photogrammetric means in urban areas, and 
others relying heavily upon them, particularly to integrate existing ground networks on different datums. 
Questions not put to the panel, due to the shortage of time, included the photogrammetric revision of urban 
maps, the problems involved in field completion surveys, the co-ordination of photogrammetric surveys in 
urban areas and their comparative costs with respect to ground survey methods.