can pictures from 1952— 53, as well as a railroad line, staked in the 
same way, between Lower Buchanan and the Bassa Mine Area, à 
distance of about 50 km. In addition to this band-shaped photography, 
1. €. a single strip, some areas had to be taken of which the Buchanan, 
the Bassa and the Nimba areas were the most important. It may be 
mentioned that the program had to be extended also when the photo- 
graphy was going on. Thus, for instance, some areas had to be taken in 
connection to the railroad line where the staking passed some critical 
sections. 
Due to the accuracy required, the aerial photography has been carried 
out from flying heights between 1 200—4 000 m. 
2.32 Organization of the Photographic Service 
In November 1957, the photographic group started from Sweden in 
a twin-engined aircraft of the type of Aero-Commander, especially 
equipped for aerial photography, with the international Liberian air- 
port Roberts Field as destination.1) 
The camera installation was a Wild Aviogon RC 8. Due to the cli- 
matic problems the need of infra-red material was an obvious fact, so 
an infra-camera of the type of Infragon was desirable. At that time, 
however, it proved to be impossible to get such a camera and the only 
way was to adapt an infra-filter to the Aviogon camera. It has to be 
pointed out that the Wild Company had already mentioned that this fil- 
ter is especially designed for interpretation purpose. Of course, the 
intention was to use it for such purpose first of all, but this infra-filter 
represented a possibility, too, if an extremely hazy weather would make 
the use of pancro-film impossible. This supposition was going to turn 
out to be more than true — the infra-film had to be used much more 
than expected because of the haze (harmattan) but also of the fog in 
the mountains. Consequently, the group had procured an outfit of re- 
gular panchromatic film as well as of infra-film. 
As decided, the film had to be developed in Liberia, since it was 
considered necessary to get information as soon as possible after the 
flying. l'or that purpose, a laboratory including a dark-room was estab- 
lished at Roberts Field. For safety, all the film was developed in the 
night.2) 
1) The camera and the laboratory equipment were placed at the group's disposal 
by courtesy of The Geographical Survey Office (Rikets Allminna Kartverk) 
Stockholm, and Airborne Mapping Ltd. Stockholm. 
2) The group under ‘the auther’s managemant, consisted of Messrs. Adolfsson 
and von Wachenfeldt, the Geographical Survey Office, being the technical staff, 
and Messr. Isacsson and Strindberg, Aero-Nord AB, as the crew. The Aero- 
Commander was chartered from this company. 
In view of the positive experiences of the infra-filter in question The Geo- 
graphical Survey Office has taken into consideration to manufacture a compensat- 
ing plate adapted to the stereo-instrument resulting in a model free from lens dis- 
tortion. 
7 
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