This Elevation Grid is a raster representation of land elevation of Wisconsin, derived from the US Geological Survey's 10-meter National Elevation Dataset (NED). The NED is a seamless mosaic of best-available elevation data. In addition to the availability of complete 7.5-minute data, USGS developed processing methods 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. The specifications for the NED 1 arc second (30 meter) and 1/3 arc second (10 meter) data are: Geographic coordinate system Horizontal datum of NAD83, except for AK which is NAD27; Vertical datum of NAVD88, except for AK which is NAVD29 Z units of meters
Geospatial elevation data are utilized by the scientific and resource management communities for global change research, hydrologic modeling, resource monitoring, mapping, and visualization applications.
WDNR obtained these USGS-produced NED 10-meter resolution data from MapMart, a division of Intrasearch, Inc., in July 2009. No spatial metadata from USGS was provided, so the data source, processing method, and resolution at the time MapMart obtained the data from USGS are not available. USGS continues to improve the NED 10m product, and provides shapefiles of spatial metadata when downloading the data. The NED data were mosaicked to cover Wisconsin, projected to WTM83(91), and clipped using a 5000 meter buffer of the state perimeter. Separate data sets of hillshading, percent slope, and slope aspect were derived. Additional terrain derivatives for hydrologic modelling or cartographic purposes may be produced in the future. After USGS completes the updates of the NED 10m product, it may be advisable to replace all of these layers. For information about the source USGS NED, see "The National Map - Elevation, Fact Sheet 2009-3053": http://pubs.usgs.gov/fs/2009/3053/ .
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None. Acknowlegement of the originating agencies (USGS, WDNR) would be appreciated in products derived from these data.
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The data exisits within a consistent data structure as an ESRI raster.
The NED10m Elevation data is visually inspected for completeness for the purpose of performing a final quality control and identifying any edits which may be needed.
see: http://ned.usgs.gov/downloads/documents/NED_Accuracy.pdf
Spatial Metadata was not provided by the vendor, MapMart. Refer to USGS NED site for spatial metadata to be included in the future. See: http://ned.usgs.gov/downloads/documents/NED_DataDictionary.pdf and current NED Release Notes. http://ned.usgs.gov/downloads.asp "Multi-resolution NED In addition to the standard 1-arc-second resolution, NED data for all of the continental United States are available in 1/3-arc-second resolution (approximately 10 meters).These higher resolution data have been produced where 10-meter DEMs and other higher-resolution DEMs are available as NED source data. The current release of 1/3-arc-second NED (April 5, 2010) includes all USGS 10-meter and 1/3-arc-second DEMs produced as of March 8, 2010. Figure 6 shows the current coverage of 1/3-arc-second NED over CONUS. In addition, 1/3-arc-second NED is available over Hawaii and the Pacific basin islands. As with 1-arc-second NED, some of the 1/3-arc-second NED is derived from ?non-standard? source data (data other than standard USGS 7.5-minute DEMs). As new source data (either higher resolution data or USGS 10-meter DEMs) become available, production of 1/3-arc-second NED will continue, and additional areas will be made available as they are completed. The data are available for download through the Seamless Data Distribution System (SDDS) (http://seamless.usgs.gov) or may be ordered for bulk data delivery via hard drive through USGS EROS Customer Service custserv@usgs.gov (605-594-6151) ." "The 1/3-arc-second NED shown in Figure 6 currently covers 100% of the United States (excluding Alaska). However, source data with a resolution of 10 meters or higher currently exists for only 91% of the United States (excluding Alaska); the other 9% of the current 1/3-arc-second NED coverage is derived from oversampling of 30-meter DEM source data. The oversampling of 30-meter data occurs where no high resolution (10-meter or better) data exist. Figure 7 shows the distribution of source data resolution within the current 1/3-arc-second NED coverage. The NED spatial metadata delivered with each order can be queried to determine the source data used to produce the 1/3-arc-second NED over any given area. As new high resolution source data become available, either from 10-meter DEMs or other sources, the data derived from 30-meter DEMs will be replaced. Oversampled 30-meter data has been assembled into the 1/3-arc-second NED as a convenience to the user community. If the data were not available from the SDDS download site, users would have to complete the oversampling themselves for many study areas."
see: http://ned.usgs.gov/Ned/methodology.asp "Processing Procedures: Development of the NED required the merging of over 50,000 different DEM data files. A processing system was designed to assemble a seamless dataset from multiple data sources, resolutions, and production methods. Procedures were developed to maintain the database with periodic updates and to insure the integration of higher resolution elevation data as they become available. A raster data model referenced to a geographic grid was used for NED. The data model is logically seamless but uses an internal tile structure initially selected as a 1- by 1-degree area. The NED dataset currently achieves complete national coverage by integrating the "best" available data in the USGS Sales Database database. Even with the "best" available, there could be a wide range of source dates and some artifacts in the source DEM. The NED assemble process identifies all existing DEM's available from data producers. The system filters production artifacts, and performs any necessary datum conversions and coordinate transformations. The NED data is only as good as the orginal source DEM. Individual DEM files are appended together into the larger tile structure specified for the database. Edge matching and metadata generation are applied lastly in assembling each NED tile. The specific procedures adopted and the issues addressed in building the NED are discussed in the following steps: Identification of Existing DEM's Datum and Elevation Conversions Projection Transformation and Resampling Artifact Corrections Merge of Multiple Data Sources Edge Matching" "Specifications: Technical Specifications Operational Specifications Business Specifications" WDNR mosaiced, projected, and clipped the data. A variety of .LYR files are available for rendering.
Metadata imported.
Internal feature number.
ESRI
No entities are represented; elevation is the only attribute information included in the NED 10m Elevation data. Elevations are expressed in feet relative to the North American Vertical Datum of 1988 (NAVD88). Since the file is referenced to WTM83(91) in meters, ArcView Spatial Analyst users should be conscious of this difference in units when deriving analytical themes such as Percent Slope.
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