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3.2. 
Since the introduction of automatic contrast control, better diapositives can be made, hence more 
details can be plotted from each stereo pair. Automation in the measuring and in the processing 
of photo coordinates (Stereomat) increases the productivity and may even, to a certain extent, 
improve the accuracy. The detailed analysis of how these developments in equipment and mate- 
rial are achieved pertains to Commissions I, IT and III. But the study of their influence on the 
methods, on the quality of results and on the efficiency of photogrammetry constitutes the task 
of Commission IV. 
The following examples should give an idea of the kind of developments, informations and trends 
analysed by Commission IV.—The latest increase in accuracy in the measurements and in plotting 
is only considered as necessarily wise for detailed surveys where the expense is justified. The 
magnitude of the tasks ahead requires the development of simple methods and instruments, just 
adequate as to accuracy, but enabling the delivery of coordinates, maps and plans within a time 
and at a cost fitting the purpose.—Automation has not only influence on the photogrammetric 
techniques as such, but bears also on the procedures of those who use the results of photogram- 
metric work. Furthermore, automation as applied to photogrammetry entails new requirements 
for data processing systems. The cooperation of the photogrammetrists with the users of the 
results (for instance civil engineers, land surveyors), or with the mathematicians who do the 
programming, has to be studied and improved. The goal to be attained with such team work is 
to make the most complete and rational use of the relevant informations contained in the aerial 
photographs. The results will serve as building-stones for providing a sensitive and searching 
humanity with sound economics. Potentialities and limitations of automation will have to be 
determined according to this ultimate purpose. 
More specifically, the developments which should be worth discussion when the interested parties 
are brought together in London will be the ones sketched hereunder. It is to the particular pro- 
blems within these main themes that the introductive talks, publications and discussions should 
deliver concrete solutions. 
High accuracy photogrammetry for large scale maps, cadastral survey, engineering design 
(A/C/IV/1) 
Inquiries and supervised tests show that the accuracies requested by the users of coordinates and 
maps can be actually reached. The accuracies obtained in mountainous terrain (for example in 
the *Monti di Revóira" survey) are practically as good as the ones reached in flat terrain (for 
instance in **Oberriet"). The supervised tests show however that the risk of coarse errors is still 
too large. Further tests will have to show how better methods of marking points on the ground 
and identifying them on the photographs can help avoiding these errors. The high cost of such 
tests should bring about a cooperation with other organizations (for instance OEEPE). It would 
increase their reliability if the temporary test field would become a permanent one (a step which 
is within the competence of the supervising authority). One would then also be able to extend the 
scope of the investigations, and to get broader statistical data. 
Cadastral photogrammetry has reached a point where surveying of valuable agricultural land can 
be done with acceptable accuracy and reasonable cost under due consideration of exacting legal 
and economic requirements. This results from the possibility of recording automatically the 
machine coordinates, and from the automatic execution of coordinate transformations and area 
computations. Such procedures are however not rational for solving the rather formidable cadas- 
tral tasks pending in the whole world. Simpler methods have to be designed, taking into account 
the large size of the regions to be surveyed, the time available, the acceptable costs, and the degree 
of interest of the people in land ownership. Aerial photography and photogrammetry are offering 
the most adequate solutions to these problems. Cadastral surveying should be considered in the 
following phases of evolution: 1. enlargement of aerial photographs with identification of the 
cadastral objects, 2. photogrammetry without marking of terrain points, 3. graphical plotting of