Type Raster Dataset
To show the elevation of terrain on Yap.
This dataset shows the elevation of Yap and its lagoon islands. The Digital Elevation Model (DEM) with a resolution of 1/3 arc-second (approximately 10 meters) was created by U.S. Geological Survey based on topography compiled in 1969. It is part of the National Elevation Dataset (NED) and also shown on the 2001 topographic map. The NED serves the elevation layer of The National Map, and provides basic elevation information for earth science studies and mapping applications in the United States. Scientists and resource managers use NED data for global change research, hydrologic modeling, resource monitoring, mapping and visualization, and many other applications. The NED is an elevation dataset that consists of seamless layers and a high resolution layer. Each of these layers are composed of the best available raster elevation data of the conterminous United States, Alaska, Hawaii, territorial islands, Mexico and Canada. The NED is updated continually as new data become available. All NED data are in the public domain. The NED are derived from diverse source data that are processed to a common coordinate system and unit of vertical measure.
U.S. Geological Survey (USGS), EROS Data Center U.S. Department of Agriculture (USDA) Natural Resources Conservation Services, National Cartography & Geospatial Center Island Research & Education Initiative (iREi)
There are no expressed warranties associated with the release of these databases. Specifically, no warranty is made that the GIS data or any subsequent updates will be error free and no warranty is made regarding the positional or thematic accuracy of the GIS data. The GIS data and any features it depicts do not represent or confer any legal rights, privileges, benefits, boundaries or claims of any kind.
There is no extent for this item.
There is no scale range for this item.
The dataset is included in the Digital Atlas of Micronesia, module Yap, by Island Research & Education Initiative (iREi) in collaboration with Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam and funding from United States Geological Survey (USGS) under WRRI 104-B Program and FSM Department of Environment, Climate Change & Emergency Management (DECEM).
U.S. Geological Survey (USGS), EROS Data Center U.S. Department of Agriculture (USDA) Natural Resources Conservation Services, National Cartography & Geospatial Center Island Research & Education Initiative (iREi)
Year topography was compiled
There are no expressed warranties associated with the release of these databases. Specifically, no warranty is made that the GIS data or any subsequent updates will be error free and no warranty is made regarding the positional or thematic accuracy of the GIS data. The GIS data and any features it depicts do not represent or confer any legal rights, privileges, benefits, boundaries or claims of any kind.
The data is acquired from USGS as Oracle Transportable Tablespaces. It is loaded to NCGC SDE servers and extracted in a UTM projection by gateway ArcObjects services.
The U.S. Geological Survey has developed a National Elevation Database (NED).The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to a consistent datum, edge-match, fill slivers of missing data at quadrangle seams, recast the data to a consistent geographic projection and convert all elevation values to decimal meters as a consistent unit of measure. NED has a resolution of one-third arc-second (approximately 10 meters) for much of the conterminous United States, Hawaii and Puerto Rico in a NAD83 datum. There is a resolution of two arc-seconds for Alaska and the datum is NAD27. NED at 10 meters is created using the same methods outlined above with the source data being mostly the 10m DEMs. DEMs at 5 meters, 1/3 arc-second, and 1/9 arc-second maps are also used where available. In some cases, the 10m NED is resampled from LIDAR or created using aerial photography. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives. Artifact removal greatly improves the quality of the slope, shaded-relief, and synthetic drainage information that can be derived from the elevation data. Geospatial elevation data are used by the scientific and resource management communities for global change research, hydrologic modeling, resource monitoring, mapping, and visualization applications. NRCS has elected to ONLY serve NED 10 which is 10 meter or better and not NED 10 which was resampled from 30 meter. NRCS also serves the maps in a UTM projection. These two facts differentiate the maps from those served at http://seamless.usgs.gov/.
The U.S. Geological Survey has developed a National Elevation Dataset (NED). The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation data for the conterminous United States are the primary initial source data. In addition to the availability of complete 7.5-minute data, efficient processing methods were developed to filter production artifacts in the existing data, convert to the NAD83 datum, edge-match, and fill slivers of missing data at quadrangle seams. One of the effects of the NED processing steps is a much-improved base of elevation data for calculating slope and hydrologic derivatives.
1. Merged separate .tif files into single file; 2. Clipped data; 3. Created metadata based on original metadata information supplied as html document.
To create a seamless DEM that covers the main island and its lagoon islands (Note that the data available from the National Map website does not cover all the lagoon islands)
ArcInfo Grid - Cell Size: one arc-second Data type: floating point Number of Rows: varies Number of Lines: varies Projection: UTM Datum: NAD83 Horizontal Units: meters Zunits: meters ArcView Shapefile - Three File Types: .dbf. shp. shx, prj Enhanced Shaded Relief - tif and tfw files as geotiff ned30m_metadata.xml ned30m_metadata.html ned30m_readme.txt USGS_NED10m_factsheet.pdf
U.S. Department of the Interior, U.S. Geological Survey, 1998, Standards for Digital Elevation Models: Reston, VA. Softcopy in Adobe Acrobat Portable Document File (PDF) format: <http://rockyweb.cr.usgs.gov/nmpstds/demstds.html>