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to the summer field season we acquired aerial photography of the study
site. Digitized aerial photographs were needed to construct the first
input layer in the GIS and serve as a real world back drop for comparison
and updates of field collected data sets. A complete set of 9 inch by
9 inch black and white aerial photographs (91 photographs) were purchased
from the Survey and Mapping Division of the Solomon Islands Ministry
of Agriculture and Lands in Honiara. The photographs were taken in 1984
at an elevation of 12,500 feet, which translates into a ground scale
of 1:24,000. Color aerial photography of about 30% (30 photographs also
at 1:24,000 scale) of the lagoon area, produced by an Australian company
in 1992, was also acquired from the Solomon Island government. In order
to incorporate the aerial photography into our GIS we needed to transform
the analog photographs into digital imagery. We accomplished this by
digitizing or scanning the aerial photographs on an high resolution
flatbed scanner. Each of the 91 photographs was carefully scanned at
600 dots per square inch (dpi) and saved in 8-bit grayscale, TIFF format.
The color photographs were also scanned at 600 dpi, but were scanned
as 24-bit true color images. The images added up to be over 5 gigabytes
worth of data. At 600 dpi our ground resolution is approximately 1 meter
for the 9 inch by 9 inch format aerial photos. In other words each pixel
in the digitized aerial photograph is a 1 meter by 1 meter square on
the earth's surface, which is an adequate resolution for the spatial
analysis that we intend carry out in this project.
Click on the thumbnails below to see some samples of our digitized aerial photographs:
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