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Targets
| In vastly wooded areas, man-made features such as
buildings, roads, and telephone poles are not available or are incorrectly
situated to be suitable control points. This problem usually occurs in
mountainous, heavily wooded areas and necessitates use of pre-flight panels
(targets) placed in optional positions within or near the area to be mapped.
These artificial targets are then tied into control surveys. These targets
will be used for precise measurements and to orient the entire mapping
correctly and therefore, care must be used in producing and placing them.
(Click here for more info on target
materials and placement) |
Target sizes vary depending on the photo scale. Use the menu above
to find
out how big your
targets should be. (Round to the closest photo scale)
| "+" Target 
|
Use photo scale menu above to find out dimensions of targets. |
| "T" Target
 |
 Click
on thumbnails for larger version.
PANELS (TARGETS): The panels
should be of weatherproof material and should stand out against the
background surface. An easy and economical target can be made up with
tarpaper and painted white or made of bleached cotton sheeting, white
mercerized cotton bunting or white muslin. Caution should be exercised so
sun reflection does not render the target useless. For this reason, plastic
sheeting or high gloss material should not be used. If the target is to be
placed on an asphalt road or paved parking lot, white waterproof paint can
be used directly on the hard surface. On any concrete roadway black paint
can be used.
When placing the targets, one should refer to the general areas marked by us
on the figure accompanying the proposal. Since the aerial photography will occur between
the hours of 9:30 a.m. – 3:30 p.m. for Spring flights, and 10:30 a.m – 1:30
p.m. for Fall/Winter flights, be certain that the targets are sunlit and
shadow free during these hours. Placement should occur within the red cross
and blue squared area on the map just prior to flight time in order to
minimize the possibility of damage or loss. The target should be placed on a
flat, but not necessarily level spot that is not obscured by evergreen trees
or dark shadows. It is best to position the targets anywhere within the
marked area that is open and free from deep shadows (i.e. we have asked for
a target on the property corner, but that corner is obscured by evergreen
trees - it would then be necessary to move the target to an open area such
as a swamp or hardwood stand). If it is necessary to move a target more than
three hundred feet (300’), please contact us for advice. |
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