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produced by private or government undertakings. By 
this alteration of methods the identification of the 
details in the field, which previously was no problem, 
has been a selfdependent working-phase. To a greater 
extent PI has been used to settle the map content. In 
some cases the map content has definitely been settled 
with this method, but in the case that no errors can be 
permitted it is necessary to use a field controlling 
method. For such a control the Geographical Survey 
Office has taken helicopters in service. 
Certain efforts were directed towards the study of 
the topography below water surfaces. The Swedish Board 
of Skipping and Navigation has a practical interest in 
the localization of shoals as well as in the exact 
knowledge of shorelines. For one or both of these pur- 
poses the use of colour film was tried but with only 
limited success. In order to extend the depth range 
below the water surface the use of ortochromatic film 
in connection with green filters was tested, but proved 
not yet to be successful. The infrared photographs 
however, which were made in order to obtain a sharp 
definition of the coastline, proved to be a clear suc- 
cess. 
Finland: 
Mr. Osmo Niemel&, Commission VII reporter for Finland, 
reportes the following use of photographic interpreta- 
tion in topographic mapping in Finland (Information 
supplied by Mr. H. E. Lyytik&inen): 
Photographic interpretation has been used in topo- 
graphic mapping in scale 1:10 000 mainly to locate the 
ground figures on aerial photographs in connection of 
field survey. Only a small part of ground features 
have been drawn in advance. Yet the final classifica- 
tion of these features has been done in the field. The 
ground figures as well as the contour lines for topo- 
graphic maps in scale 1:100 000 are now being drawn in 
advance as office work using stereotop-plotters. These 
drawings will be controlled and completed in the field. 
A special mounting of stereopairs using fixed strips of 
photographs in & width of eyebase has been developed in 
orden to ease stereoscopic interpretation by the aid of 
simple stereoglasses. 
The following is a report by Mr. Seppo Penttila 
on the use of aerial photographs in the Institute of 
Geology, Finland. During the last 15 years aerial 
photographs have been generally used as a substitute 
for base maps where adequate map coverage has not been 
available. The photographs and mosaics have been 
specially useful in carrying out aeroprospecting. 
Photographic interpretation has been applied to geolo- 
gic purposes only for about ten years. At first the 
photoanalysis has been used to speed up soil surveys. 
This method has been most useful in Lapland, where soil 
surveying in connection with water power projects have 
been carried out mainly by photointerpretation. In map- 
ping of bedrocks photointerpretation has been used as a 
tool for comparison of tectoric conditions of the bed- 
rock. 
Topographic maps have also been drawn in some extent 
with two Stereotop instruments in the Institute and 
comparisons have been made to find out the most suit- 
able camera, emulsion and picture scale for different 
branches of research work. 
Germany: 
From Germany we have the following summary of in- 
vestigations along the coast of El Salvador by 
Von H. G. Gierloff-Emden. (4) 
In 1954-55, the author traveled along the coast of 
Salvador. With the aid of his own field work and by 
exploiting several air photographs, he plotted maps of 
the two large lagoons of Salvador and of the western 
part of the Gulf of Fonseca. These maps are based on 
the preliminary print of an auxiliary rectified air 
plan from which the outlines of the represented area 
were taken for reference to the new geodetic grid of 
longitudes and letitudes of Salvador. 
The maps of the two lagoons, i.e. that of the Estero 
de Jaltepeque and that of the Estero de Jiquilisco, pub- 
lished in the annex, are the first exact large scale maps 
that have until now been plotted of these two coastal re- 
gions. In accordance with their state of survey of 1955, 
they make clear that all former representations on small 
Scale maps in atlasses and on charts require to be care- 
fully rectified. This is, before all, due (4) Deutsche 
Hydrographische Zeitschrift, Band 12, Heft 1, 1959, to 
the high variability of the mangrove bordered lagoons and 
to the never ceasing process of building up and destroy- 
ing beach ridges under the action of current and sand 
transport. The map of the Gulf of Fonseca shows the 
correct positions of the coastal line and of the islands. 
From the new air photographs it can be seen that the 
positions of the coast and of the islands as they have 
been represented on the charts now in use are not in ac- 
cordance with the actual state. The configuration of 
the submarine sea floor in the Gulf of Fonseca was de- 
rived from contour lines and by exploiting the author's 
and other soundings. 
The names of the localities have been in detail as- 
certained by travelling about and are inserted on the 
maps together with the designation of the morphology of 
small forms. 
Canada : 
Mr. S. T. B. Losee, Chief Fhotogranmetrist for the 
Abitibi Power and Paper Co. LTD. sent in the following 
Canadian national report: 
The Prairie Farm Rehabilitation branch of the Dominion 
Department of Agriculture uses photographic interpreta- 
tion extensively in their work. They list the following 
types of projects during 1956-60. 
Dam site analysis 
Canal routes 
Irrigable and reclamation areas 
Watershed studies (topography, soils, vegeta- 
tion, and storage possibilities) 
Potential water supplies 
Construction material searches 
Potential land use surveys (in relation to 
grazing) 
The photographs used are summer panchromatics at scales 
of 1:15,840 and 1:31,680. 
J. D. Mollard and Associates, consulting engineers, 
prepared the following compilation of their projects 
during 1956-59: 
TYPE OF PHOTO INTERPRETATION STUDY NUMBER OF PROJECTS 
A. Construction-Material Searches  ....... 169 
(Note--Since 1956 this company has 
searched 82,000 square miles and 
mapped 4,350 prospects from aerial 
photos.) 
B. Site-Investigation Studies bes 65 
(Note--Included above are damsites 
and reservoirs, bridge sites, land 
slides, new townsites, industrial 
sites, steam and hydro plant sites.) 
M 
+= 
C. Municipal-Engineering Studies ....... 
D. Route Studies 2... 54 
(Note--Included here are highway, 
railway, powerline, canal, and pipe- 
line studies carried out by photo- 
interpretation. The lines studied in 
photos vary in length from less than a 
mile to over 500 miles. And the total 
miles studied runs in to several 1000s 
of miles. 
  
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14 77124-60