might need two, three, or four pictures to show the
different sides of a building; or you might make a near
and a distant view of the pinpoint target--one to show
detail and the other to show location. You can also make
more than one shot to produce one large, detailed
picture of a pinpoint target. In this case, three or four
shots having a 60-percent overlap are made. For
example, you may need three overlapping exposures to
give a large, detailed view of both ends and the middle
of a bridge. When the number of overlapped exposures
is small, say four or less, either vertical or oblique
photographs, the total composition may be called a
pinpoint aerial photograph, but technically, it would be
either a strip or a mosaic.
A strip is a series of overlapping exposures matched
together to form one long picture. A strip is used when
your assignment calls for photographing long, narrow
targets, such as railroads, highways, coastlines, rivers,
and mountain ridges. You may hold the camera at any
angle to make a strip; however, exposures made with
the camera pointing straight down from the aircraft join
together better and have the most consistent scale. A
strip comprised of oblique views is called a
One long, continuous picture, made from a number
of photographs, requires the images to be matched
carefully so one picture ends where the next begins.
Because the camera is in a different position for each
exposure, a perfect match is impossible. But, by
overlapping exposures and using only the central area
of each picture, you can obtain a near-perfect result.
Once a strip is started, photographing it is a
mechanical job because the aircraft flies at a constant
speed and at a constant altitude. You should not alter
the camera angle while exposing a strip, and you should
make the exposures at regular intervals. Thus the
longer the strip, the more an automatic camera system
is preferred. The camera-to-scene distance must remain
constant while you are making the strip. The smallest
change in distance changes the image size and makes
matching adjacent exposures extremely difficult, if not
Large land areas are photographed in strips that
overlap sideways. The strips are pieced together to
form one large composite picture, called a MOSAIC.
When photographing for mosaic purposes, you should
keep the camera the same distance from the scene
throughout the photographing evolution. Mosaics are
usually produced from vertical photographs made by
aircraft with an automatic camera system.
Two pictures of the same subject, photographed
properly, can provide a stereoscopic or three-
dimensional effect. The two pictures are called a
word STEREOGRAM indicates that the two pictures are
mounted and ready for stereo viewing.
The primary purpose of stereo aerial photography
is to provide measurements, such as height and depth,
and detect features that are not visible in a regular
photograph. Photo interpreters (Intelligence
Specialists) are trained in stereo techniques to detect
these fine points. Stereo photographs are produced by
making two pictures of the same subject from slightly
different positions. When the pictures are made from
the same position, the two are identical and there is not
a stereo effect. A very small shift in the camera
position, between exposures, produces a very shallow
stereoscopic depth. As you increase the shift in camera
position between exposures, the apparent depth of the
stereoscopic view increases. When the stereo effect is
exaggerated--so hills appear steeper and depressions
appear deeper than they really are--the effect is called
HYPERSTEREOSCOPY. The terms inverted stereo,
pseudo stereo, and reverse stereo refer to the effect of
interchanging the position of the pictures, causing hills
to appear as valleys and valleys to appear as hills.
Another aspect of aerial photography that you
should be concerned with is reconnaissance
p h o t o g r a p h y . T h e N a v y p e r f o r m s a e r i a l
reconnaissance photography of enemy territory to
observe enemy defenses, troop concentrations, troop
movements, enemy strength, and so on. Aerial
reconnaissance photography may also include taking
images over friendly territory, both ours and our Allies.
This is discussed further in the TARPS section of this
Cartographic photography is accomplished for the
purpose of making charts and maps. Usually several
strips are flown over known landmarks that are used as
reference points or ground-control points.
Cartographic photography always has vertical views

Advanced Photography Course

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