can do it justice at all. We could say that terrain analysis like many other things
are products of photo interpretation and is a matter of convergence of evidence.
This requires work of several scientists of different disciplines; many of the
techniques we discussed this morning would bear on the subject for example, the
papers on tonal lineaments by Mr. Olive, regional analysis by Mr. Heath, in
struments and techniques by Mr. Ray are heading in this direction. Terrain
analysis is therefore not a single field in itself. To make best use of photos we
have to call on soil scientist, geologist, geographers and vegetation specialists.
In order to improve trafficability analyses methods, we should also be de
veloping photographic interpretation aids, keys and devices specifically aimed
at this work. We should also examine and reexamine the uses that we can put
plotting instruments that have been developed for precise plotting work. We
have touched on their application to geology and forestry but I believe we can
gain much by applying these instruments in many other fields related to
trafficability.
L’emploi de l’appareil de restitution Kelsh est discuté. Il est indiqué que cet instrument s’est
montré utile pour les levés de côtes dans les travaux géologiques et forestiers. La précision des
résultats dépend des possibilités de contrôle terrestre. Dans les travaux de reconnaissance géologique
aux Etats-Unis et en Alaska, une précision suffisante est obtenue par l’usage de cartes à l’échelle
de 1/250 000 pour le contrôle horizontal et de lacs et de fleuves ou du baromètre anéroide pour le
contrôle vertical.
L’interprétation de la traficabilité est également discutée.
Minutes of the Proceedings of July 23, 1956, Session c,
military photographic interpretation
Captain R. Thor en, Sweden, acted as chairman and opened the session, with L. Reed: The Role of
a few remarks. Mr. L. Reed, of U.S.A. read his paper, on The Role of Photo- Photo-Interpretation m
^ ^ Air Torce Charting.
Interpretation in Air Force Charting: (Publ. VIIR 2)
Several years ago the advent of the aerial photograph provided the carto
grapher with a picture from which he could make accurate measurements and
identify ground features without actually visiting the area; the photograph
made our cartographer embrace the field of photo-interpretation. This was
especially true of the Air Force cartographer and it is because of his position
today that the title is selected »The Role of Photo-Interpretation in Air Force
Charting». Explanation is given of some of the general requirements for photo
graphy and some of the problems that are solved by applying photo-interpreta
tion techniques at the Aeronautical Chart and Information Center, St. Louis,
Missouri.
Generally, Air Force photography should provide the maximum possible co
verage per photograph and yet retain the detail necessary to meet charting
requirements; a certain amount of detail must be sacrificed. The measure of
success lies in the resolution attained, that minimum resolution which will give
us the percentage of image characteristics which must be captured before photo
interpretation can fill in that detail expression which is lost. How much image
characteristics can be lost, and just what the happy-medium might be between
flying altitude and image resolution, is discussed in terms of requirements. This
constitutes a main concern of air force charting that affects our cartographer in
his photo-interpretation task.
Many types of photography are used in charting operations today, but when
expansive coverage is the problem, the higher altitude photographs are desired,
including high obliques. For this reason, and because aeronautical charting has
certain special characteristics, the compilation task calls for various degrees of
photo-interpretation ability. Examples are: Interpretation for general area
portrayal, including geological features, photo control selection and feature
delineation when using oblique photographs, determination of height and con-
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