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,Click here to access the data directly from the Illinois State Geospatial Data Clearinghouse.,These lidar data are processed Classified LAS 1.4 files, formatted to 2,117 individual 2500 ft x 2500 ft tiles; used to create Reflectance Images, 3D breaklines and hydro-flattened DEMs as necessary. Geographic Extent: Lake county, Illinois covering approximately 466 square miles. Dataset Description: WI Kenosha-Racine Counties and IL 4 County QL1 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a derived nominal pulse spacing (NPS) of 1 point every 0.35 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011), State Plane, U.S Survey Feet and vertical datum of NAVD88 (GEOID12B), U.S. Survey Feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 2,117 individual 2500 ft x 2500 ft tiles, as tiled Reflectance Imagery, and as tiled bare earth DEMs; all tiled to the same 2500 ft x 2500 ft schema. Ground Conditions: Lidar was collected April-May 2017, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Ayers established a total of 66 ground control points that were used to calibrate the lidar to known ground locations established throughout the WI Kenosha-Racine Counties and IL 4 County QL1 project area. An additional 195 independent accuracy checkpoints, 116 in Bare Earth and Urban landcovers (116 NVA points), 79 in Tall Grass and Brushland/Low Trees categories (79 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.,Users should be aware that temporal changes may have occurred since this dataset was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.,These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.,Link Source: Illinois Geospatial Data Clearinghouse,

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,This dataset has been deprecated. Please use our 2017 Digital Elevation Models instead.,The Digital Surface Model (DSM) is a 3-foot pixel resolution raster in GeoTIFF format. This was created using all points (excluding NOISE) from our 2007 LiDAR data without incorporating the breaklines. Merrick and Co. MARS (ver. 8.0.4, build 8185) software was used to create the GeoTIFF images.,The DSMs were developed using LiDAR data. LiDAR is an acronym for LIght Detection And Ranging. Light detection and ranging is the science of using a laser to measure distances to specific points. A specially equipped airplane with positioning tools and LiDAR technology was used to measure the distance to the surface of the earth. The classified points were developed using data collected in April to May 2007. The LiDAR points, specialized software, and technology provide the ability to create a high precision three-dimensional digital elevation and/or terrain models (DEM/DTM) as well as digital surface models (DSM). The use of LiDAR significantly reduces the cost for developing this information.,The DSMs are intended to correspond to the orthometric heights of the surface of the county including above ground features such as buildings, vegetation cover, utility structures, vehicles ... etc. DSM data are used by county agencies and others to study drainage issues such as flooding and erosion; contour generation; slope and aspect; and hill shade images. Elevation data and models are used in several different ways including:,Visualization representations of the elevation data. Examples include:,- A hillshaded or shaded relief image,- An image representing slope,- An image representing aspect,Analysis of the elevation data and analytical products which can be generated. Examples include:,- Viewshed calculations for visibility and line-of-sight analysis,- Areas of highest Solar energy potential,- Uses in disaster management,- Industrial planning,- Calculation of cartographic contours,- Calculation of profiles along straight lines or line segments,These data are derived from other data sources, no accuracy measurements or tests were conducted. Primary use and intent for these data are for visualizations and topographic analysis. This dataset does not take the place of an on-site survey for design, construction or regulatory purposes.,

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,This dataset has been deprecated. Please use our 2017 Countywide Contours instead.,These data comprise of one foot contours showing the elevation of Lake County, IL corresponding to the orthometric heights of the bare surface of the county (no buildings or vegetation cover). These data were developed from LIDAR data obtained between April 16, 2007 and May 07, 2007, and further supplemented by break lines collected from aerial photography taken at the same time. The contours and the aerial photography meet National Map Accuracy Standards for a 1 inch = 100 foot product. The contours have been created to be cartographically pleasing, as such some generalization has been introduced as expected. The contours have been tested against the original LIDAR points and conforms to the American Society for Photogrammetry and Remote Sensing (ASPRS) Specifications and Standards Committee, 1990, ASPRS Accuracy Standards for Large-Scale Maps, CLASS 1 map accuracy. The vertical datum is the North American Vertical Datum of 1988.,The U.S. Army Corps of Engineers Engineering and Design Manual for Photogrammetric Production recommends that data intended for this usage scale be used for any of the following purposes: route location, preliminary alignment and design, preliminary project planning, hydraulic sections, rough earthwork estimates, or high-gradient terrain / low unit cost earthwork excavation estimates. The manual does not recommend that these data be used for final design, excavation and grading plans, earthwork computations for bid estimates or contract measurement and payment.,Contour data is used by county agencies to study drainage issues such as flooding and erosion. Customers interested in the actual LiDAR data may download it at no cost from the USGS Center for LiDAR Information Coordination and Knowledge.,These files are tiled by PLSS section and grouped by township and format for easier download. Please note that this dataset is available in for GIS in Esri shapefile format as well as for CAD in AutoCAD DWG and MicroStation DGN. We are unable to provide any support for CAD users beyond providing the data.,