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<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>These contours were derived from Digital Elevation Model (DEM) data. Class 2 (Ground) lidar points in conjunction with the hydro breaklines were used to create a 0.5 meter hydro-flattened Raster DEM. Geographic Extent: Becker, Clay, Otter Trail, and Wilkin counties, Minnesota, covering approximately 4649 square miles. Dataset Description: The lidar project called for the planning, acquisition, processing, and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 2.1. The data was developed based on a horizontal projection/datum of NAD83 (2011), UTM Zone 15 North, Meters and vertical datum of NAVD88 (GEOID18), Meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 12293 individual 1000 m x 1000 m tiles clipped to the DPA, as tiled Intensity Images, as tiled Bare-Earth DEMs, as tiled All-Return MSHRs; all tiled to the same 1000 m x 1000 m schema. Ground Conditions: Lidar was collected in late 2021, 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, Sanborn Map Company, Inc., established a total of 47 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 155 independent accuracy check points, 92 in bare earth and urban landcovers (92 NVA points), 63 in tall grass and brushland/low trees categories (63 VVA points), were used to assess the vertical accuracy of the data. These check points were not used to calibrate or post process the data.</SPAN></P></DIV></DIV></DIV> |