Ground Validation Data Used to Map Benthic Habitats of the Republic of Palau

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 incorporate previously developed mapping methods to produce benthic habitat maps generated by photo interpreting georeferenced IKONOS satellite imagery. These point data were generated to conduct ground validation during map preparation.

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 purpose of this survey was to investigate areas of imagery where uncertainties exist on the photo interpreter's behalf during the decision making process of benthic habitat type for Palau.

616

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.

Contact NOAA for distribution options (see Distributor).;

None

Not for navigation

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 9.0.0.535

The points in this thematic data layer were acquired by GPS data using a Trimble GeoExplorer 3 with a customized data dictionary designed to reflect the NOAA Classification Scheme for Benthic Habitats of the Pacific 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. Attributes are all expected to be correct.

Point accuracy was determined by three tests producing circular RMS statistic. Point GPS data were acquired by repeated occupation of a fixed point yielding a 95% sigma RMS of 5 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 ground validation data are at least 95% sigma of 5 meters.

1140 field positions were occupied and habitat characterization conducted for ground validation during this work. These data were included in the dataset as a GIS layer and the first draft map was edited based on this ground truth. All areas where uncertainty existed on the part of the photo interpreter during habitat delineation were investigated in the field. All data were collected and integrated into the mapped products as planned.

The sites for ground validation were selected to specifically investigate habitat types and gradients of spectral signatures. All areas where uncertainty existed on the part of the photo interpreter during habitat delineation were investigated in the field. Waypoints in these areas were generated on the georeferenced imagery. The waypoints were navigated to and occupied. The habitat was observed and GPS data collected. One hundred GPS positions were collected at one-second intervals for each survey site. The positions were averaged to obtain a single survey point. The data were post processed for differential correction. The general area was explored and, as needed, additional GPS positions were collected to mark transitions between habitat types of areas mapped at the level of the minimum mapping unit (MMU). These data are believed to be consistent.