PHOTOGRAMMETRIC ENGINEERING
details seen in aerial photographs that are too
small or so subtle that they are not noted in
general mapping practice. Micro-features em-
brace more than micro-relief. They also in-
clude color tones, drainage, and vegetative
patterns, all present in a degree of subtlety
that falls below the usual concept of signifi-
cance. Micro-features are important because
they are the means by which refined identifi-
cation can be made when mapping various
types of bedrock, soil materials, and struc-
tural relationships.
Micro-relief can be defined as those relief
characteristics that are not reflected on con-
tour maps. But they do not necessarily fall
of ability and experience. The necessary oper-
ations to perform are seeing and recognizing.
One may see an object and not recognize it.
Or one may know of the possibility of the ex-
istence of an object but not see it. Micro-fea-
tures then fall into the class of things not
within normal experience and not knowing
they occur, how does one know what to look
for? The answer is experience, experience,
experience; in the laboratory, in the field, and
in research.
The optical-nerve system that makes up
the eye and brain linkage is highly complex,
and the fact that one depends upon the other
for its complete functioning is important in
ABSTRACT: Micro-features are described as minor details of the earth’s surface,
seen in aerial photographs, which are either too small or too subtle to be noted in
normal mapping practice. They include micro-relief (changes in elevation of
less than contour interval), as well as changes in tones, drainage and vegetative
patterns. Micro-features, properly analyzed, provide a wealth of information
as to the identification of bedrock, the determination of soil materials and geo-
logic structural relationships. The use of color photography raises the level of
visibility of many micro-features, and brings them into the realm of recognition
for use in many types of analytical studies.
( Mikro-Gestaltungen werden bezeichnet als geringere Einselheiten der Ober-
Jlaeche der Erde, die aus Lufibildern ersichtlich sind, und die entweder zu klein
oder zu fein angelegt sind, um in normalen Landkarten Verzeichnungen beo-
bachtet werden zu koennen. Darin eingeschlossen sind Mikro-Relief (Veraen-
derungen in Erhoehungen in geringerem Grade denn Schichtlinien Abstaende) |
sowie auch Veraenderungen in Schattierungen, Entwaesserung und Pflanzen- | |
wuchs Muster. Mikro-Gestaltungen, richtig zergliedert, ergeben einen Ueberfluss
von Information betreffend Kennzeichnung festen Gebirges, die Bestimmung der
Boden Grundstoffe und geologisch organische Verbindungen. Die Verwendung |
farbiger Luftbilder erhebt das Niveau der Sichbarkeit von vielen Mikro-Gestalt- |
ungen, und bringt sie in das Gebiet hoechster Anerkennung fuer Gebrauch in |
vielen Typen analytischer Erforschungen.)
below one specific contour differential such
as two or five or ten feet. In general they are
related to the texture of the terrain so that a
detail of micro-relief in mountainous terrain
may be more massive than that occurring on
an alluvial plain, and yet neither appear on
contour maps appropriate to the respective
terrain types. And it is not purely a matter of
elevation but also one of mass, because these
subtle features are of relatively small areal ex-
tent.
Micro-features can be said to occupy a po-
sition at or on the threshold of identification,
sometimes above and sometimes below.
Whether or not they can be identified is not
necessarily a matter of photography. Assum-
ing an average scale of 1:20,000 and average
quality, then identification becomes a matter
this problem. This is borne out by the oft-
repeated statement, "Now that you show it to
me, I can see it." The eye passes over the
micro-feature but the brain doesn't record it.
If the eyes and brain have experienced this be-
fore, then the eyes will 'see" and the brain
"record." Papers have been written and pre-
sented to serious audiences that have cate-
gorically stated, for example, that gabbros
cannot be identified in aerial photography.
This is typical of a mind that knows that
something cannot be done. With this influ-
ence predominating, then the eyes will not see
and the brain, of course, will not record.
The term micro-feature, rather than mi-
cro-relief, is often more descriptive because
these identifying features are combinations of
relief, drainage condition, tone, and vegeta-
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