Accuracy Assessment Field Data for American Samoa

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; BAE Systems Spectral Solutions; and Analytical Laboratories of Hawaii, LLC. The goal of the work was to incorporate previously developed mapping methods to produce coral reef habitat maps for American Samoa, Guam and the Commonwealth of the Northern Mariana Islands. GPS field observations were used to establish the thematic accuracy of this thematic product. 651 benthic habitat characterizations were completed for this work.

The National Ocean Service is preparing digital map products of these biotic resources and coordinates a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities. The goal of the work was to implement previously developed coral reef mapping methods to produce GIS map products of benthic habitats by photo interpreting georeferenced remotely sensed imagery. These Accuracy Assessment point data were generated to assess the accuracy of the individual maps created from IKONOS satellite imagery.

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The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) produced this data CD-ROM. NCCOS Biogeography Branch does not guarantee the accuracy of the geographic features or attributes. Please see the metadata records for each data set for complete information on the source, limitations, and proper use.

Contact NOAA for distribution options (see Distributor).;

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The points in this thematic data were acquired by GPS using a Trimble GeoExplorer 3 with a customized data dictionary designed to reflect the NOAA Classification Scheme for Benthic Habitats of the Pacific. All habitat determinations were made in the field, recorded in the GPS data logger and seamlessly transferred to ArcView GIS using Trimble Path Finder Office Software.

Point accuracy was determined by three tests producing circular RMS statistic. Point GPS data were acquired by repeated occupation a fixed point yielding a 95% sigma RMS of 2 meters compared to the position mean. Replicate GPS positions were collected after navigating to a way point by boat yielding RMS value of 5 meters. Registered monuments were occupied and replicate positions collected yielding an RMS value of 3 meters. Thus, all point features in these accuracy assessment data are at least 95% sigma of 5 meters.

Data are complete. Habitat attributes are determined by direct observation in the field. These data are considered truth at the time of collection. Habitat types are subject to change over time due to population dynamics of the dominant biological communities.

To maintain objectivity in the analysis of accuracy, all field observations were withheld from the photointerpreter. Furthermore, Coral Reef Assessment and Monitoring Program (CRAMP) of the Hawaii Institute of Marine Biology (HIMB) conducted the determination of the extent to which the photointerpretation met the field assessment determinations. These data were then used to prepare the statistical report of the accuracy of the maps.Transfer of the habitat assessment data is seamless from the field determination to the final GIS product. The data is not transcribed or rewritten by hand. Errors in processing are not expected.