2 REPORT OF THE INSTITUTE OF INDUSTRIAL SCIENCE, UNIVERSITY OF TOKYO
These will be helpful as a practical guide to the interpretation of aerial photos taken
for purposes of civil engineering projects.
1. PREFACE
If one soars in the sky he can take the fields and mountains in one view and there is
nothing that obstructs the view. If we take photographs of such scenery and minutely analyze
various terrains and natural features on the earth mirrored in the photos, we would surely be
able to discover great many things which might not be detected by simple reconnaissance we
make while walking on the ground. In fact, if the persons who see photos have a rudimen-
tary knowledge, they will be able not only to comprehend natural features on the earth and
terrains but also trace the history centuries ago. They can even interpret the geological struc-
ture and the distribution of subterranean soil.
Photogrammetry has recently made rapid strides in Japan but its mission was primarily
limited to chart maps by using aerial photos. On many occasions aerial photos used for mapping
are either turned into mosaic photos and are exhibited in a drawing room or are tucked away
in the closet.
Although aerial photos are restricted in the details to be reproduced by the performance
of lenses and films or by reduction of photos, they are a miniature copy of the actual place
as it is and any artificial intension would not be involved in it at all. Moreover, conditions
on the site are reproduced intact in tones having limitless shades from white to black.
It needs no explanation how valuable and effective the factual records with no trace of
artificiality are for all scientific investigations.
Ways must be devised to fully utilize aerial photos in various surveys and researches,
without limiting their uses for tracing maps.
Recently a new science aimed at analyzing geological sturucture by using aerial photos
has been advocated. It is called photogeology and a considerable literature already exists on
the subject. In fact, to rove over hill and dale and scan the rock by conducting numerous
boring operations are a Herculean task from the standpoint of both labor and expense. If
we can grasp the outline of geological structure through aerial photos and select the location
suitable for boring—— which will result in the reduction in the number of boring sites——
and if we can conduct an on-the-spot survey on the basis of the results which had been thor-
oughly screened from aerial photos beforehand, it will more than offset the expense needed
for taking aerial photos.
This thesis isa part of the results of our study of photogeology. We keep our study of
photogeology itself for another occasion and here we will exemplify how useful infrared photos
are in the study of stratigraphy or underground water as compared with formerly used pan-
chromatic photos.
What we call geology here is geology relevant to public works- that is, civil engi-
neering geology and not geology which professional geologists expound.
Infrared photos had so far been utilized for specific purposes. Considered from the
phase of utilization, it is an extremely interesting problem how the objects come out if we
take infrared photos from a high altitude. However, even the most fundamental problem——
under what conditions should we take infrared aerial photo if we are to obtain the most ideal
photo
has not yet been cleared up. So we had to start from scratch.
This report describes the state of our fundamental study, recent examples of infrared
photos applied to civil engineering and the results thereof.
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