Illinois State Geological Survey 20160315 This Digital Terrain Model (DTM) data was produced all or in part from LiDAR information as of 2015. The LiDAR derived DTM covers Clinton County, Illinois and include inland streams, rivers, lakes ponds and tidal features. These data are appropriate for use in local and regional analysis. This data set has a vertical accuracy of 6.24 centimeters RMSEz, horizontal accuracy of 0.6 meters and point spacing of 0.89 meters. Digital Elevation Models (including terrain and surface models) are raster data sets created from whole LiDAR point cloud data sets (LAS files). The LAS files are the standard LiDAR file format which contains the raw point cloud data, these data are normally classified and distinguished between points on the ground, water or elevated features such as buildings, trees, towers, bridges, etc.. These LAS files are processed into elevation models to create gridded rasters. The first returns can be used to map the top reflective surface (Digital Surface Models - DSM), these normally include open terrain areas, as well as the tops of buildings, trees, towers, and other features elevated above the bare earth. The last returns are used to map the bare-earth terrain (Digital Terrain Models - DTM), these are normally produced with irregularly-spaced points rather than the uniform grid structure of a Digital Elevation Model (DEM), Digital Terrain Models will often include breaklines to help define edges of water bodies. These acquisitions of the LiDAR data and its derivatives were made possible by a grant from the National Geodetic Survey for the National Height Modernization Program. The program is in place to enable states access to accurate, reliable heights using global positioning satellite (GPS) technology in conjunction with traditional leveling, gravity, and modern remote sensing technologies. LiDAR data and its derivatives assist in real-world uses around the state of Illinois such as; highway engineering, flood prediction, agricultural land management, mining subsidence, monitoring archaeological features, locating sinkholes and applied geologic science. The data do not replace the need for detailed site-specific studies. The information is not appropriate for, and is not to be used as, a geodetic, legal, or engineering base. The 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. 20150101 20150315 dates of collection Complete As needed -89.72 -89.12 38.75 38.41 None Digital Elevation Data Light Detection and Ranging LiDAR Bare Earth Point Cloud Digital Elevation Model DEM Elevation Surface Model Digital Surface Model DSM Hillshade Clinton County Access Constraints ISGS information must be obtained directly from the ISGS or from an authorized distributor. Be aware that ISGS information obtained from an unauthorized third party may have been altered subsequent to original distribution, or may no longer be current. Any access to these data, Web sites, computer systems, electronic services, and electronic networks is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. 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, isgs@isgs.illinois.edu. License fees and a license agreement may be required, depending on the proposed usage. Any use of these data is governed by University and campus policies, in particular, but not limited to, the Policy on Appropriate Use of Computers and Network Systems at the University of Illinois at Urbana-Champaign, the ISGS Terms of Use document available at the ISGS Web site, and the University of Illinois Web Privacy Notice. Links to these are provided in the Cross References section. 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. Illinois State Geological Survey mailing and physical

615 E Peabody Dr.

Champaign IL 61821 US 217-333-4747 info@isgs.edu Monday thru Friday 8 am to 5 pm Illinois Department of Natural Resources, Illinois State Geological Survey, Illinois Department of Transportation and Surdex Corp. Some Known Errors (Within the USGS base specifications thresholds) are: 1) The LAS files, the EPSG code for the horizontal projection, 32767, does not actually exist. 2) The contract for Clinton County state USGS base 1 specifications to be used, but the metadata utilizes base 1.2 standards. 3) There is a sporadic issue of small lakes and ponds, and small streams that do not have breaklines on them that are either classified as ground or model keypoints. 4) There is a sporadic issue of points that represent structures being misclassified into one of the vegetation classes. Most of these instances have been resolved but not all. 5)The breakline elevation on the portion of Carlyle Lake located on tile #25350735 and #25350730, is out of tolerance. It has been determined that the error was caused by a difference in the height of water at the time of collection. The adjoining flight line are about a week apart. USGS base specs say that breaklines for lakes are to have a flat elevation, resulting in what we see here. 6) There are visible flight lines, but the elevation difference between the two is within industry standards. none ISGS Secondary Processing: 1. Thorough QAQC check was completed to ensure and evaluate the quality of the data delivered and that all the specifications have been met in accordance to the contract and national specifications set for LiDAR data. 2. Through ArcGIS 10.1 the following steps were completed to created Terrain and hillshade products: a. LAS to Mulitpoint conversion using 3D analyst tools.ASPRS Classifications were used below: 1-Unclassified 2-Ground 3-Low Vegetation ( less than 1.5 meters or less than 5 feet) 4-Medium Vegetation (1.5 - 4.5 meters or 5 - 15 feet) 5-High Vegetation (4.5 meters and above or 15 feet and above) 6-Building 8-Model Key Points 9-Water b. Terrains are then created and pyramids are calculated. c. Terrain to Raster tool was used in 3D Analyst. The parameters of data type float, natural neighbors method, sampling distance is cell size and the point spaceing value from the LiDAR data. d. Hillshades are created from the above rasters with a Z value of 2. 3. These derivatives were checked again visually for errors. If any errors were perceived corrections were coordinated with vendor and products were updated with corrections. 4. When product was finalized then metadata was completed before making data available. 20160315 The class field is defined as: Class 1 (Default/unclassified) Class 2 (Ground) Class 3 (Low Vegetation) Class 4 (Medium Vegetation) Class 5 (High Vegetation) Class 6 (Structures/Building) Class 7 (Noise) Class 9 (Water) Class 10 (Breakline Proximity) Class 17 Overlap (Default/unclassified) Class 18 Overlap (Ground) Class 19 Overlap (Low Vegetation) Class 20 Overlap (Medium Vegetation) Class 21 Overlap (High Vegetation) Class 22 Overlap (Structures/Building) Class 23 Overlap (Noise) Class 24 Overlap (Keypoint) Class 25 Overlap (Water) Class 26 Overlap ( Breakline Proximity) ASPRS 20160315 Illinois State Geological Survey mailing and physical

615 E Peabody Dr.

Champaign IL 61821 US 217-333-4747 info@isgs.edu Monday thru Friday 8 am to 5 pm FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998 local time