2000 Photo Mosaics and Hyperspectral Imagery for the Main Eight Hawaiian Islands Utilized to Map Shallow Water Benthic Habitats

This project is a cooperative effort among the National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Monitoring and Assessment; the University of Hawaii; and Analytical Laboratories of Hawaii, LLC. The goal of the work was to develop coral reef mapping methods and compare benthic habitat maps generated by photointerpreting georeferenced color aerial photography and hyperspectral imagery. Aerial photographs were acquired for the Main Eight Hawaiian Islands Benthic Mapping Project in 2000 by NOAA Aircraft Operation Centers aircraft and National Geodetic Survey cameras and personnel. Approximately 1,500, color, 9 by 9 inch photos were taken of the coastal waters of the Main Eight Hawaiian Islands at 1:24,000 scale. Specific sun angle and maximum percent cloud cover restrictions were adhered to when possible during photography missions to ensure collection of high quality imagery for the purpose of benthic mapping. In addition, consecutive photos were taken at 60 percent overlap on individual flight lines and 30 percent overlap on adjacent flight lines to allow for orthorectification and elimination of sun glint. The enhanced spectral resolution of hyperspectral and control of bandwidths of multispectral data yield an advantage over color aerial photography particularly when coral health and time series analysis of coral reef community structure are of interest. The AURORA hyperspectral imaging system collected 72 ten nm bands in visible and near infrared spectral range with a 3 meter pixel resolution. The data was processed to select band widths, which optimized feature detection in shallow and deep water. The digital scans of aerial photos and hyperspectral imagery were orthorectified to eliminate sources of spatial distortion. With these orthorectified images photointerpreters can accurately and reliably delineate boundaries of features in the imagery as they appear on the computer monitor using a software interface such as the Habitat Digitizer.

The National Ocean Service is conducting research to digitally map biotic resources and coordinate a long-term monitoring program that can detect and predict change in U.S. coral reefs and their associated habitats and biological communities.

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Spatial Reference Information Planar_Coordinate_Information: Abscissa_Resolution: 1.0 m (photomosaics) 3.0 m (hyperspectral imagery); Ordinate_Resolution: 1.0 (photomosaics) 3.0 (hyperspectral imagery)

The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) produced this data CD-ROM. NCCOS Biogeography Program does not guarantee the accuracy of the geographic features or attributes.

Project information is available online or on CD-ROM through the NCCOS Biogeography Program.;

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PHOTOMOSAICS Average spatial accuracy of individual photomosaics is reported in Chapter 3 of Benthic Habitats of the Main Hawaiian Islands. Positional accuracy was determined by solution of Softplotter generated model (RMS less than 1) and by comparison to independent ground control data. The georegistration of these photographs is at least 95% sigma RMS of 5 meters. HYPERSPECTRAL IMAGERY Hyperspectral imagery was obtained at 3 meter pixel resolution.

PHOTOMOSAICS No color balancing was attempted since this alters color and textural signatures in the original imagery and interferes with the photointerpreter's ability to delineate habitats. As a results mosaics have visible seams between adjacent photos. This provides the photointerpreter with "true color" imagery for maximum ability to identify and delineate benthic features. HYPERSPECTRAL IMAGERY Habitat delineations could be made accurately in water depths up to 30 meters. Band combinations were selected which optimized benthic habitat information in shallow and deep water and the scenes were converted into RGB composites

PHOTOMOSAICS Once all of the photographs were orthorectified, the best segments of each photograph were selected for creation of the final mosaic. Segments of each photograph were selected to minimize sun glint, cloud interference, and turbidity in the final mosaic. Whenever possible, parts of images obscured by sun glint or clouds were replaced with cloud/glint free parts of overlapping images. As a result, most mosaics have few or no clouds or sun glint obscuring bottom features. HYPERSPECTRAL IMAGERY All habitat delineations were completed by a photointerpreter on data that had been processed only to maximize specific band widths for viewing data at varying depths.