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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