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Data from the Landsat Thematic Mapper (TM) satellite were merged with
SPOT satellite data to create a composite image of the entire state of
Louisiana. The merged image acquires the advantageous features of each
satellite. TM imagery are multispectral - detecting energy in seven
bands of the visible and infrared wavelengths of the electromagnetic
spectrum. The SPOT imagery utilized for this merger is panchromatic - a
black and white single band primarily spanning the full visible range
of the spectrum. TM imagery has a resolution of 30 meters while SPOT
panchromatic imagery is 10 meters. When the two data sets are
mathematically merged, the resulting imagery has the characteristics of
the original data - that is, it appears as a color 10 meter image,
acquiring the multispectral feature of the TM and the higher resolution
of the SPOT.
The final image is a result of using the RGB (red, green, blue)
composite of band 4 (near-infrared), band 5 (mid-infrared), and band 3
(red visible) from the TM fused with the SPOT panchromatic data. Global
and local histogram functions were applied to the data prior to
merging. After merging, the images were reduced from 3 band, 24 bit
files to single band 8 bit files that retain the true color fidelity of
the composite color image. The 4, 5, 3 combination provides the
greatest degree of vegetative discrimination and accounts for the
various hues of red, orange and green seen in vegetated areas. The
merged images are paneled in 30x30 minute tiles equivalent to 16
U.S.G.S 7.5 minute quadrangles, 100k U.S.G.S quadrangles, and parishes.
The TM data were aquired during the 1992-93 winter, and the SPOT data
were aquired during the 1990-95 time period. The data are projected to
UTM Zone 15, Clarke 1866 ellipsoid, NAD 27 datum
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