Abert, Curtis C., 1995, Digital Elevation Model (DEM) of Illinois at 1:250,000: ISGS GIS Database GISDB.IL_DEM_301FT_RAS, Illinois State Geological Survey, Champaign, Illinois, USA.
This is a Raster data set. It contains the following raster data types:
The map projection used is Lambert Conformal Conic.
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 301.930524
Ordinates (y-coordinates) are specified to the nearest 301.930524
Planar coordinates are specified in survey feet
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378206.400000.
The flattening of the ellipsoid used is 1/294.978698.
Sequential unique whole numbers that are automatically generated.
These data were assembled to provide a statewide database of surface elevation points suitable for analyses of statewide geologic phenomena associated with elevation. The data have been used to generate slope data and shaded relief images, and are appropriate for other such regional applications.
These data are appropriate for use in local and regional elevation analysis. The data are not appropriate as a geodetic, legal or engineering base. The data set can serve as an important base cartographic and analytical element for many types of maps. The data set was not and is not intended as a substitute for surveyed elevations, such as can be determined by a registered Public Land Surveyor.
United States Geological Survey, unknown, 1:250,000 Digital Elevation Models: USGS DEMs All tiles necessary to provide complete coverage of Illinois, including a 9 mile buffer, USGS, unknown.
Person who carried out this activity:
, University of Illinois Web Privacy Notice.
, University Copyright Policy (stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4).
, Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign.
Derived from United States Geological Survey 1:250,000-scale 3 arc-second Digital Elevation Model data. Contact the USGS for attribute accuracy of the source DEM data. Some elevation data at the edges of individual DEM tiles were smoothed for edge-matching purposes.
Assumed to be as accurate as USGS 3 arc-second DEMs.
USGS 3 arc-second DEMs projected into Lambert Conformal Conic projection were resampled to an approximate 301 foot cell size.
Not applicable to grids.
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Links to these are provided in the Cross References section.
- ISGS information is the property of and copyrighted by the Board of Trustees of the University of Illinois with all rights reserved. University copyright policy is stated in the General Rules Concerning University Organization and Procedure, Article III, Section 4. A link is provided in the Cross References section.
Individuals or entities may make fair use of copyrighted ISGS material, such as reproducing a single figure or table, or using a brief text quotation, without obtaining formal permission, but in all cases the Illinois State Geological Survey must be credited as the source of the material. To reproduce ISGS information beyond the fair use standard, permission must be obtained from the ISGS Information Office, 615 East Peabody Drive, Champaign, Illinois 61820, 217-333-4747, firstname.lastname@example.org. License fees and a license agreement may be required, depending on the proposed usage.
Map information is to be used at a scientifically and cartographically appropriate scale, that is, at a scale no greater than indicated on the map or as described in the documentation of the map or map data. Map information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. Map information has no legal basis in the definition of boundaries or property lines and is not intended as a substitute for surveyed locations such as can be determined by a registered Public Land Surveyor.
The data do not replace the need for detailed site-specific studies.
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The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, ESRI formats can be imported into many different GIS software packages. It is expected that customers who obtain these data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.
Illinois Natural Resources Geospatial Data ClearinghouseGenerated by mp version 2.8.25 on Thu Apr 02 09:54:01 2009