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AeroMap U.S. is a division of Aero-Metric Inc., one of the
largest photogrammetric companies in the United States. AeroMap
is based in Anchorage, Alaska, and is a full-service Geographic
Information and Mapping Sciences firm, with expertise in all
areas of aerial survey, airborne remote sensing, and satellite
image processing. AeroMap's clients include government agencies,
and private sector organizations which use airborne imagery
for various applications, from environmental monitoring to
engineering design work.
Faced with limited good flying weather and the rugged Alaskan
environment, AeroMap was tasked with capturing color aerial
photography for the Federal Bureau of Indian Affairs. The
Class II Orthophotography project involved generating images
for approximately 500 native allotments in the Calista Native
Lands area of western Alaska. The allotments were scattered
throughout the region, and could be as far apart as 200 miles
or share a common boundary, and vary in size between 20 and
150 acres. "It was a difficult assignment in which to
capture the images efficiently, so precise coordination was
required," Dean Cimmiyotti explained. "As the orthophotos
would be used to assess the timber stands in each allotment,
positional accuracy was an important consideration, particularly
as vector data was to be overlaid to show the individual property
limits."
Film Camera Survey
"The POS AV system enabled us to complete
this project very cost effectively because we
could georeference our aerial imagery without
surveying multiple ground control points."
With accessibility and logistical concerns associated with
carrying out a complete ground control survey in this area
of Kuskokwim, AeroMap decided to use their POS AV system to
generate direct georeferenced imagery, eliminate the need
for aerotriangulation, and easily meet the Class II requirement
of 5' horizontal positioning. "Using the POS AV allowed
us to fly single lines with as few as 3 or 4 images per allotment.
To verify the accuracy of the georeferenced data we used a
minimum amount of ground control as a QC check," said
Cimmiyotti, "and it exceeded our expectations."
The final georeferenced imagery was used to generate a Digital
Elevation Model, which allowed the orthophotos to be produced
quickly. Digital vector data, provided by the Bureau of Land
Management, was then accurately overlaid to illustrate the
individual allotment boundaries. Since incorporating the POS
AV system into its workflow, AeroMap has found that increased
productivity and additional accuracy are readily attainable
under the difficult conditions encountered in Alaska, streamlining
their airborne surveys into a precise and efficient operation.
