This DEM is a mosaicked model of USGS 30x30 meter DEMs, showing 1:24,000-SCALE quadrangle map boundaries that extend in an irregular buffer outside the state boundary. The ISGS and USGS shared the cost to update a number of the DEMs from Level 1 (low quality) elevation data to Level 2 (best quality) to make this the highest resolution, statewide DEM coverage currently available. Due to budget constraints, an area in southeastern Illinois area has not been upgraded to Level 2 elevation data. The difference in quality is noticeable by the horizontal striping characteristic of Level 1 elevation data.
Luman, Donald, Smith, Lisa, and Goldsmith, Chris, 2003, Illinois Statewide 30-Meter Digital Elevation Model: ISGS GIS Database IL_DEM_30M_RAS, Illinois State Geological Survey, Champaign, IL.This is part of the following larger work.
Luman, Donald, Smith, Lisa, and Goldsmith, Chris, 2003, Illinois Surface Topography: Illinois Map 11, Illinois State Geological Survey, Champaign, Illinois, USA.
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest 30.000000
Ordinates (y-coordinates) are specified to the nearest 30.000000
Planar coordinates are specified in meters
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 developed to produce an ISGS publication entitled Illinois Surface Topography, Illinois Map 11, 2003.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.
, USGS DEMs.
Person who carried out this activity:
Person who carried out this activity:
Person who carried out this activity:
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Should be consistant for NMAS specification for a 1:24000 scale map.
Half the contour interval of the original USGS topographic survey. A typical interval for Illinois is ten feet although other ranges exist.
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Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Reproduction or redistribution of copyrighted digital data sets or products derived therefrom outside of licensee's organization or entity is expressly forbidden. The only exception is redistribution to consultants working for the licensee, and then only for purposes, related to work for the licensee. Such consultants may not further reproduce or redistribute these data sets. None of these data shall be electronically duplicated on magnetic or optical media for use by others, in whole or in part, without permission of DNR.
Any hardcopies utilizing DNR data sets shall clearly indicate their source. If the licensee has modified the data in any way they are obligated to describe the types of modifications they have performed on the hardcopy map. Licensee specifically agrees not to misrepresent DNR data sets, nor to imply that changes they made were approved by DNR.
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The Illinois Department of Natural Resources (DNR) provides these geographic data "as is." DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. DNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers of DNR, no warranty, expressed or implied, is made by DNR regarding the use of these data on any other system, nor does the fact of distribution constitute or imply any such warranty.In no event shall the DNR have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data or arising out of the delivery, installation, operation, or support by DNR.
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The data are intended for use with GIS software. The ISGS uses ESRI ArcGIS software, however, the ESRI shapefile format can be imported into many different GIS software packages. It is expected that customers who order this data have the technical expertise to use GIS software. The ISGS does not provide software support of any kind.
Illinois Natural Resources Geospatial Data Clearinghouse
Generated by mp version 2.8.11 on Wed Jul 11 15:26:21 2007