provide baseline spatial information about benthic habitat types and extent. The
second set of studies use several years of aerial photographs to track changes over
time. The third study incorporates astronaut-acquired photographs as a secondary,
complementary data source when mapping tropical atolls with satellite imagery.
The final case study uses the spectral information from digital aerial images,
combined with bathymetric and field data, to quantitatively measure suspended
sediment in the water column of a reef-flat environment.
2.4.1 Baseline Spatial Mapping
In order to document change in any ecosystem, one must first have a baseline
inventory of resources. Benthic habitat maps, which allow spatial documentation of
the location of coral, other biologic and geologic zones, percentage of live coral
cover, and potentially the overall health of a system, are important tools used by
coral reef managers to assess change. In 1998, while recognizing the lack of such
baseline information for many United States coral reefs, the President of the U.S.
issued Executive Order 13089 establishing the U.S. Coral Reef Task Force, whose
primary duty is to preserve and protect coral reefs in the U.S. and U.S. Trust
Territories. In response to this mandate, the National Oceanic and Atmospheric
Administration (NOAA) National Ocean Service (NOS) implemented a program to
provide digital maps of United States coral reefs for use in a geographic information
system (GIS). The first benthic habitat maps completed for this program were of
Puerto Rico and the U.S. Virgin Islands (Kendall et al. 2001), followed by the Main
Hawaiian Islands (Coyne et al. 2003), the Northwestern Hawaiian Islands (National
Oceanic and Atmospheric Administration 2003), American Samoa, Guam, and the
Northern Mariana Islands (NOAA National Center for Coastal Ocean Science
2005), and the Republic of Palau (Battista et al. 2007). Mapping of other U.S. coral
reefs is ongoing. The earliest of these mapping projects were based only on aerial
photography, while more recent benthic habitat mapping projects utilized satellite
imagery in addition to aerial photography. The benthic habitat mapping of the Main
Hawaiian Islands (Coyne et al. 2003) is presented here.
Approximately 1,500 aerial photographs of the Main Eight Hawaiian Islands
were collected by NOAA in 2000 at a scale of 1:24,000. Adjacent flight lines were
flown with a 30 % overlap, and consecutive photos on each flight line were taken
with a 60 % overlap to minimize distortion and spectral variations from sunglint.
Diapositives (color transparencies) created from the original negatives were
scanned at 500 dpi to create images with a spatial resolution of 1 m per pixel.
Orthomosaics were created for each island by first applying lens parameter corrections to each image, and using airborne GPS, along with aerial triangulation
software, to provide preliminary georegistration of the images.
To provide continuity to the coral reef scientific community, a hierarchical
classification scheme was developed through a series of workshops incorporating
input from coral reef scientists, resource managers, local experts, and others.
2 Photography Application
37
second set of studies use several years of aerial photographs to track changes over
time. The third study incorporates astronaut-acquired photographs as a secondary,
complementary data source when mapping tropical atolls with satellite imagery.
The final case study uses the spectral information from digital aerial images,
combined with bathymetric and field data, to quantitatively measure suspended
sediment in the water column of a reef-flat environment.
2.4.1 Baseline Spatial Mapping
In order to document change in any ecosystem, one must first have a baseline
inventory of resources. Benthic habitat maps, which allow spatial documentation of
the location of coral, other biologic and geologic zones, percentage of live coral
cover, and potentially the overall health of a system, are important tools used by
coral reef managers to assess change. In 1998, while recognizing the lack of such
baseline information for many United States coral reefs, the President of the U.S.
issued Executive Order 13089 establishing the U.S. Coral Reef Task Force, whose
primary duty is to preserve and protect coral reefs in the U.S. and U.S. Trust
Territories. In response to this mandate, the National Oceanic and Atmospheric
Administration (NOAA) National Ocean Service (NOS) implemented a program to
provide digital maps of United States coral reefs for use in a geographic information
system (GIS). The first benthic habitat maps completed for this program were of
Puerto Rico and the U.S. Virgin Islands (Kendall et al. 2001), followed by the Main
Hawaiian Islands (Coyne et al. 2003), the Northwestern Hawaiian Islands (National
Oceanic and Atmospheric Administration 2003), American Samoa, Guam, and the
Northern Mariana Islands (NOAA National Center for Coastal Ocean Science
2005), and the Republic of Palau (Battista et al. 2007). Mapping of other U.S. coral
reefs is ongoing. The earliest of these mapping projects were based only on aerial
photography, while more recent benthic habitat mapping projects utilized satellite
imagery in addition to aerial photography. The benthic habitat mapping of the Main
Hawaiian Islands (Coyne et al. 2003) is presented here.
Approximately 1,500 aerial photographs of the Main Eight Hawaiian Islands
were collected by NOAA in 2000 at a scale of 1:24,000. Adjacent flight lines were
flown with a 30 % overlap, and consecutive photos on each flight line were taken
with a 60 % overlap to minimize distortion and spectral variations from sunglint.
Diapositives (color transparencies) created from the original negatives were
scanned at 500 dpi to create images with a spatial resolution of 1 m per pixel.
Orthomosaics were created for each island by first applying lens parameter corrections to each image, and using airborne GPS, along with aerial triangulation
software, to provide preliminary georegistration of the images.
To provide continuity to the coral reef scientific community, a hierarchical
classification scheme was developed through a series of workshops incorporating
input from coral reef scientists, resource managers, local experts, and others.
2 Photography Application
37