TM 5-852-2/AFR 88-19, Vol. 2
(10) Type of prints. For most interpretation
arctic and subarctic terrain features. A more com-
work, semi-matte finished (9- by 9-inch) contact
prehensive treatment of this aspect of photo analysis
prints on RC (resin coated) paper are advisable. The
can be investigated through the references shown in
option to request enlargements from (9- by 9-inch)
the Bibliography. The following will discuss the
aerial negatives is available, if needed for planning.
general analysis process, which is described in
(11) Flight line map or photo indices. It is very
greater detail in these references.
desirable to obtain or create a flight line map or a
(1) The stereoscopic mosaic is used in conjunc-
photo index map of the requested photo coverage.
tion with a stereoscope and the unmounted alternate
c. Assembling the stereoscopic aerial photogra-
(stereo pair) photos of each strip. The exposure
phy data base. Upon receipt of the aerial photogra-
numbers on each print are used to locate the proper
phy, all of the photos must be trimmed to the edge
stereo pair to view a particular area stereo-
of the actual image. In some instances, pertinent
scopically. The entire mosaic can be viewed in the
annotations regarding exposure number, scale, date,
third dimension using this technique.
etc., are contained in these areas, which must be
(2) The process of analyzing and interpreting
trimmed from the prints when the mosaic is
stereoscopic aerial photography draws upon the
prepared. At least the exposure numbers should be
background, experience and knowledge of the ana-
transferred inside the image boundary. An example
lyst or, better yet, a team of analysts with knowl-
of this supplementary annotation can be seen on
edge of several disciplines. It is an application of
some of the strips of photos on the stereomosaic in
logic and reasoning to synthesize data obtained by
figure 3-5.
observation and inference. It is based on a recogni-
(1) To begin creating a stereoscopic airphoto
tion of natural relationships (physical, biological and
mosaic, a suitable base material upon which the
cultural) as expressed by key pattern indications
mosaic can be stapled must be chosen. Celotex,
present in the image.
foam core and "chip board" are all suitable.
(3) A systematic approach to airphoto pattern
(2) Six strips of photography have been used to
analysis embodies three phases: first, a regional
create the example mosaic (fig. 3-5). Note that
study; second, a detailed stereoscopic study of
photos have been positioned end to end, with about
pattern elements; and third, a final interpretation of
a 10% overlap in each of the strips. Also note that
results to answer a posed question or solve a
each strip overlaps the adjacent strip by about 30%.
problem.
(a) A regional study, such as has been con-
The photos not laid down as part of the mosaic are
set aside and labeled to show in which strip they
ducted using the example Landsat image, considers
belong. These are used for stereoscopic analysis in
the broad, overall aspects of an area in terms of
conjunction with the completed mosaic. It is
physical makeup of the landscape; origin, type and
important to lay out the strip of photos in a way that
distribution of materials; broad natural vegetation
allows each print number to show, so that the
assemblages; surface hydrology; and land use
unmounted stereo pair photos that have been set
patterns. The results of a regional study give a team
aside can be used in their proper sequence. Since
an overview and assessment of an area in which
each photo is slightly distorted in scale from the
numerous landscape patterns can be recognized,
center outward, the trick in laying a stereoscopic
delineated and associated. The study also serves to
photomosaic lies in allowing a very small degree of
suggest areas within the region that might be most
offset between every photo and strip, so that large
suitable for potential site selection and where more
offsets are not created toward the periphery of the
detailed study should be undertaken by using larger
entire mosaic. Also, by laying out the center strip or
scale imagery.
(b) A regional study is followed by a de-tailed
two first, with as close a match as possible, any
accumulation of offset is thereby forced to the outer
stereoscopic study of smaller areas selected from the
edges of the mosaic.
regional analysis. Here each pattern element is
(3) All six strips of photos are laid out loosely in
systematically studied and evaluated to accurately
this manner, with weights to hold them in position
determine the character of the physical, biological,
for a final adjustment. This final adjustment is made
and cultural components of the landscape.
by making slight shifts among all the photos to
Landforms, surface drainage, depositional and
obtain a best match. Then the mosaic can then be
erosional aspects, photographic tones, and
stapled fast to the base.
biological and cultural aspects are all observed and
d. Terrain and environmental factor mapping. It
evaluated as elements of the photo pattern. This
is not the intent of this chapter to the teach photo
detailed analysis, coupled with existing information
patterns and corresponding ground conditions for
in the form of published reports, surveys,
3-8
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