Donald Luman Lisa Smith Chris Goldsmith 2003 1.0 remote-sensing image ISGS GIS Database IL_DEM_30M_RAS Champaign, IL Illinois State Geological Survey Donald Luman Lisa Smith Chris Goldsmith 2003 map Illinois Map 11 Champaign, Illinois, USA Illinois State Geological Survey Scale, 1:500,000. Size, 36 x 54 inches. Color. This data set is a digital elevation model (DEM) of Illinois in ArcInfo grid format. The data are stored in UTM coordinates, using a Transverse Mercator projection with the parameters of UTM Zone 16, NAD27. The data have a 30-meter ground resolution. The x- and y-coordinate values are in meters and the z-values are in feet. 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. 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. 20011018 Last update with updated USGS DEM data Complete None planned -91.5336 -87.2490 42.6108 36.8568 None DEM digital elevation model elevation 30-meter U.S. Department of Commerce, 1977, Countries, dependencies,areas of special sovereignty, and their principal administrative divisions (Federal Information Processing Standard 10-3): Washington, D.C., National Institute of Standards and Technology. IL None 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. Please refer to the distribution information. ArcGIS 9.1 on Windows None. None. None. 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. 24000 Imported USGS DEMs to ESRI GRID lattices. 2001 Standardized all DEMs to UTM 15 or 16 NAD27 with vertical units in feet, and a cell size of 30 meters. Some DEMs that had a datum of NAD83 were projected to NAD27 with cubic resampling. Vertical units were in feet, meters, and decimeters and were converted by simple multiplication and rounded to the nearest whole foot. DEMs with a 10 meter cell size were resized to a 30 meter grid spacing with cubic resampling. 2001 Due to a limitation in GRID on the number of input grids while mosaicking all the DEMs were first mosaicked into one degree blocks (latitude and longitude) and then into full mosaicks of the UTM 15 and 16 zones in Illinois. Null areas were fillled in by simple averaging of the surrounding cells. 2001 Final assembly of the statewide DEM was accomplished by reprojecting the UTM 15 side of the state to UTM 16 with cubic resampling and then mosaicking it with the UTM 16 zone. 2001 The final grid was imported into the ISGS SDE database using LZ77 compression, the GISDB_RASTER configuration keyword, and a raster block size of 80 x 80. Several test loads using ISGS procedure GISDB_0016 were performed to determine the appropriate raster block size. Pyramids were built using bilinear interpolation. Dataset statistics were calculated. Database statistics (analyze function) were calculated. The metadata were updated. 20031217 Raster Grid Cell 21661 12665 1 Universal Transverse Mercator 16 0.999600 -87.000000 0.000000 500000.000000 0.000000 coordinate pair 30.000000 30.000000 meters North American Datum of 1927 Clarke 1866 6378206.400000 294.978698 1 feet IL_Dem_30m ObjectID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Value Count Cell values are in feet above sea level. Illinois State Geological Survey, Geospatial Analysis and Modeling Section mailing and physical address

615 East Peabody Drive

Champaign Illinois 61820 USA 217-333-4747 217-785-0211 isgs@isgs.uiuc.edu 8:00 a.m. - 4:30 p.m., Monday - Friday, U.S. Central Time 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. 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. 20031217 Please refer to the distribution information. Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time None None http://www.esri.com/metadata/esriprof80.html ESRI Metadata Profile