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<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Purpose: To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create intensity images, breaklines and raster DEMs. The purpose of these LiDAR data was to produce high accuracy 3D hydro-flattened digital elevation models (DEMs) with a 1-meter cell size. These raw LiDAR point cloud data were used to create classified LiDAR LAS files, intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.</SPAN></P><P><SPAN>Product: These are Digital Elevation Model (DEM) data for Northern Maine as part of the required deliverables for the Crown of Maine 2018 QL2 LiDAR project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1-meter hydro-flattened raster DEM.This lidar data set includes unclassified swath LAS 1.4 files, classified LAS 1.4 files, hydro and bridge breaklines, hydro-flattened digital elevation models (DEMs), and intensity imagery. Geographic Extent: 4 partial counties in Northern Maine, covering approximately 6,732 total square miles. Dataset Description: The Crown of Maine 2018 QL2 LiDAR project called for the planning, acquisition, processing, and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.71 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.2. The data were developed based on a horizontal projection/datum of NAD 1983 (2011), UTM Zone 19, meters and vertical datum of NAVD 1988 (GEOID 12B), meters. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 8,056 individual 1,500-meter x 1,500-meter tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 1,500-meter x 1,500-meter schema. Continuous breaklines were produced in Esri file geodatabase format. Ground Conditions: LiDAR was collected in spring of 2018 and 2019, 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, Quantum Spatial, Inc. utilized a total of 150 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 256 independent accuracy checkpoints, 149 in Bare Earth and Urban landcovers (149 NVA points), 107 in Tall Weeds categories (107 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.</SPAN></P></DIV></DIV></DIV> |
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["elevation","elev","LiDAR","derivative","Digital Elevation Model","DEM","Maine","MaineGeoLibrary","Crown of Maine","2018","2019","QL2"] |