High Spatial Resolution Digital Imagery
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proximately 44 km2 (~11,000 acres). Using an average of the total estimated
costs for the two missions, including acquisition and processing (given above)
gives a price per square km of roughly 0. This converts to approximately
.00 per acre.
The CAMIS images have a much higher cost per unit area relative to high
spatial resolution satellite imagery. The vendors of high resolution satellite im-
agery require a minimum area for purchase. Using IKONOS imagery as an ex-
ample, Space Imaging (Thornton, Colorado) has set the minimum area at 10 10
km. The price for this minimum window, assuming only basic geometric regis-
tration (i.e., not ortho-rectified), is roughly /km2 or 00. This price includes
both 1-m panchromatic and 4-m multispectral data. A rectangle measuring 20 km
wide (east/west) by 25 km long (north/south) is required to cover the Sny levee.
Therefore, cost for acquiring high resolution IKONOS imagery for this 500-km2
area would be approximately ,500. The price tag for acquiring and post-
processing the same 500-km2 area using 1-m CAMIS imagery would exceed
5,000. The satellite data are much cheaper and generally do not require sig-
nificant radiometric or geometric corrections. The IKONOS imagery must be run
through a "pan-sharpening routine." The process, available as built-in routine in
both ENVI and Imagine software packages, merges higher resolution (e.g., 1-m
pixels) panchromatic imagery with slightly lower resolution (e.g., 4-m pixels)
multispectral data to produce a simulated 1-m multispectral product. These im-
ages are excellent for manual interpretation but, with questionable radiometric
fidelity, may not always be suitable for classification with quantitative image
processing routines.
Compared with traditional aerial photography, digital imaging systems have
several cost effective advantages. The primary benefit of CAMIS-like systems is
that the raw data are provided in a digital format. Aerial photos must be trans-
formed, through scanning, from an analogue format (either paper or transpar-
ency) to a digital format. The scanned aerial frames can then be post-processed as
digital files, requiring similar radiometric and geometric post-processing steps as
with CAMIS frames. The second benefit of multi-camera digital systems is their
ability to acquire more than three spectral bands. The aerial photo mission would
have to be flown twice, with appropriate film and camera lens, to provide both
true-color and false-color images. A third benefit is total time needed to provide a
completed digital mosaic. Assuming that the appropriate hardware and software
tools are available, the multispectral imaging system could produce a radiometri-
cally balanced, geometrically corrected mosaic within 2 weeks. The analogue
photos require film developing and digital scanning just to prepare the imagery
for the digital post-processing steps. These steps are completed twice to produce
mosaics with more than three spectral bands. Assuming that the film developing
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