USGS NED 1/3 arc-second Contours for Quincy W, Illinois 20150424 1 x 1 degree Shapefile

Resource lineage description

source

source description  Source Contribution: ContoursSource Type digital data

representative resolution scale:

Scale denominator: 24000

source citation

Title Hypsography

publication  Date   2015-04-24

presentationForm  mapDigital

other Citation Details  This contour featureclass was generated from the 1/3 arc-second version of the 3D Elevation Program. The intended viewing scale for these features is 1:24,000. The contours are derived from a filtered elevation raster to achieve smoother arcs. In some areas, the 3DEP data may be modified by the National Hydrography Dataset (NHD) flow lines and water bodies to facilitate improved integration between the hypsography and hydrography on USGS map products. These contours were generated primarily for use as a layer in GeoPDFs created in the digital mapping program. The raster data source of contours is the 3D Elevation Program 1/3 arc-second layer. Secondary datasets include the high resolution flow lines, water bodies, and areas from the National Hydrography Dataset (NHD). The NHD layers are used in hydro-enforcement of the DEM prior to contour generation. The goals of the hydro-enforcement are to prevent contour lines from extending over the surface of water bodies and to align the contour reentrants with the NHD single- line streams. The 3DEP raster cells are converted to points. Those points, along with the NHD flow lines are input into an interpolation tool to create a new surface. The NHD water bodies and areas are preprocessed to attach the minimum and maximum elevation to each polygon. From these precalculated values, an appropriate value is calculated by which to raise the elevation cells under the NHD polygons. The NHD polygons are then converted into rasters, which in turn will be used to generate a mosaic that includes the new raster surface. The mosaic is filtered to provide smoother contour lines. Contours are generated and depression and index contours are identified. There is no guarantee or warranty concerning the accuracy of the data. Users should be aware that temporal changes may have occurred since these data were collected and generated and that some parts of these data may no longer represent actual surface conditions. Hydro-enforcement and generalization can also significantly alter the spatial characteristics of the contours. Users should not use these data for critical applications without a full awareness of its limitations.

cited responsible party - originator

organisation Name  U.S. Geological Survey, National Geospatial Technical Operations Center - National Elevation Dataset is a component of a comprehensive base geospatial data model.

cited responsible party -

organisation Name  

Contact information

Linkage for online resource

URL: http://Hs.gov/

AbsoluteExternalPositionalAccuracy

name Of Measure Horizontal Positional Accuracy Report

evaluation Method Description  Contours do not have well-defined position, so National Map Accuracy Standards (NMAS) for horizontal accuracy do not apply. Contour positions are, on average, accurate to within one-half contour interval

AbsoluteExternalPositionalAccuracy

name Of Measure Vertical Positional Accuracy Report

evaluation Method Description  The most recently published figure of overall absolute vertical accuracy of the 3DEP within the conterminous US, expressed as the root mean square error (RMSE) of 25,310 reference points is 1.55 meters. However, the vertical accuracy actually varies significantly across the US because of differences in source quality, terrain relief, land cover, and other factors. Details of this analysis are published in "Accuracy Assessment of the U.S. Geological Survey National Elevation Dataset, and Comparison with Other Large-Area Elevation Dataset-SRTM and ASTER: U.S. Geological Survey Open-File Report 2014-1008," http://pubs.usgs.gov/of/2014/1008/.

Completeness Commission

evaluation Method Description  The National Elevation Dataset is national in scope, with complete coverage of the conterminous 48 states, Hawaii, the US Virgin Islands and Puerto Rico. There is partial coverage for Alaska.

Completeness Omission

evaluation Method Description  The National Elevation Dataset is national in scope, with complete coverage of the conterminous 48 states, Hawaii, the US Virgin Islands and Puerto Rico. There is partial coverage for Alaska.

ConceptualConsistency

measure Description  The National Elevation Dataset is seamless. Although the data accuracy varies, the data generally have high enough resolution and accuracy to support consistent and accurate contours at 1:24,000 scale.