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Analysis of
imagery of Belize, Central America, recently acquired by the National
Aeronautics and Space Administration (NASA) Earth Observing-1 (EO-1)
satellite, shows that this experimental imagery can be used effectively
to classify a diverse set of land cover/land use types. The Bureau
of Economic Geology and Center for Space Research are investigating
the new imagery as part of a NASA-sponsored program to evaluate
the capabilities of technologically advanced sensors onboard the
EO-1 satellite to image the Earth's surface. Classification of land
cover/land use using the multispectral Advanced Land Imager (ALI)
on the satellite indicates that classifications were similar but
superior to those of Landsat 7 Enhanced Thematic Mapper (ETM+) for
several difficult classes in test data, such as thicket, regrowth,
orchards, and cleared land. In addition, ALI data appear to be superior
to Landsat TM data in delineating some coastal land-cover classes,
such as mangrove and marshes. New statistical classification methods
developed during the study yielded improved discrimination between
difficult classes in both ALI and Landsat TM data. ALI data were
also effectively used to determine impacts of Category Four Hurricane
Iris, which made landfall in southern Belize on October 8, 2001.
Comparison of post-hurricane ALI data with pre-hurricane Landsat
7 data indicated that broadleaf forest had been extensively damaged
in the Monkey River area approximately 130 km south of Belize City.
On ALI imagery acquired after the hurricane, more than 98 percent
of areas previously classified as broadleaf forest using Landsat
TM data were classified primarily as savannah and other grasslands,
indicating extensive broadleaf destruction and defoliation. A similar
analysis in inland mountainous areas that were affected by the hurricane
also showed large areas of downed and defoliated broadleaf trees.
The ALI data clearly delineated changes in spectral signatures and
textures as a result of Hurricane Iris.
Spectral data
are being classified using both existing statistical methods and
new contextual and multisensor algorithms currently being developed
at The University of Texas at Austin for multispectral and hyperspectral
data. Classification results are entered into a geographic information
system (GIS) for analysis of land-cover and land-use distribution
and change. Classified areas are checked for accuracy and consistency
using existing maps and previously collected land cover/land use
data at Global Positioning System (GPS)-located field survey sites
and overflights, supported by additional field verification sites
using GPS coordinates. Results include an evaluation and validation
of the capabilities of EO-1 and Landsat 7 ETM+ data for classifying
a diverse set of land cover/land use types and analyzing trends
such as rates of deforestation and regrowth.
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