Molokai Accuracy Assessment Point Data for Benthic Habitats of the Main Hawaiian Islands Prepared by Visual Interpretation from Remote Sensing Imagery Collected by NOAA Year 200...

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, hyperspectral and IKONOS satellite imagery. The cost effectiveness of acquisition and processing of remotely sensed imagery varies significantly between types of platforms deployed and imaging systems used to acquire the data. As a result, it is important to identify the strengths and weaknesses of the map products prepared from each of the types of digital imagery. These Accuracy Assessment point data were generated to assess the accuracy of the individual maps created from the three types of source information.Testing showed that the ability to generate benthic habitat maps with an overall accuracy of 90% to 95% confidence interval is reaching a threshold using imagery with three meter pixel size allowing for spectral enhancement of the imagery with reduced resolution. Increasing the intensity of field observation can partially compensate for this decrease in accuracy of the maps generated from the largest pixels. Habitat maps prepared from IKONOS satellite imagery should be accompanied by field observation wherever possible.

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. The goal of the work was to develop coral reef mapping methods and compare benthic habitat maps generated by photointerpreting georeferenced color aerial photography, hyperspectral and IKONOS satellite imagery. These Accuracy Assessment point data were generated to assess the accuracy of the individual maps created from the three types of source information.

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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 Program 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.

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Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 3; ESRI ArcCatalog 8.2.0.700

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 Main Eight Hawaiian Islands. 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, an independent team conducted the field assessments. The Coral Reef Assessment and Monitoring Program (CRAMP) team made all benthic habitat decisions independent of the Analytical Laboratories of Hawaii (ALH) contractor. Furthermore, the CRAMP team independently conducted the assessment of the extent to which the photointerpretation met the field assessment determinations. These data were then used to prepare the statistical contrasts of the accuracy of the maps for each of the test areas for each of the image types.Due to an unusually stormy winter in the Central Pacific during the 2001 to 2002 season, multiple attempts to acquire accuracy assessment data for the Molokai test area were required. Two field missions were planned to collect these data. Due to failed field missions resulting from poor weather; eight field missions were executed to complete this work.During the month of November 2002, an unusually powerful storm occurred in the Hawaiian Islands. Extensive flooding, road closures and power outages were experienced. The intense rain fall, after 15 years of near drought conditions in the Hawaiian Islands, resulted in unprecedented mud inundation on the east end on the study area in Molokai. The influx of sediment from the November storm and the series of storms that followed over the next six months made this area inaccessible for the entire project period.As the types of habitats on the east end of the Molokai test area are very similar to those on the west end of the test area, the density of accuracy assessment points was increased on the west end to compensate for the reduced density of the east end. With the exception of the mud inundation on the reef at Molokai, the remainder of the acquisition of field accuracy assessment data proceeded flawlessly.