Data

Product: These are one and two foot contour data as part of the required deliverables for the lidar project. Geographic Extent: Boulder, Gilpin, Grand, Jefferson counties Colorado, covering approximately 207 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), State Plane Colorado Central, US Feet and vertical datum of NAVD88 (GEOID18), US Feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 257 individual 5280 ft x 5280 ft tiles clipped to the DPA, as tiled Intensity Images, as tiled bare-earth DEMs, as tiled first-return DSMs; all tiled to the same 5280 ft x 5280 ft schema. Ground Conditions: Lidar was collected in mid-late 2020, 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 4 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 15 independent accuracy check points, 8 in Bare Earth and Urban landcovers (8 NVA points), 7 in Tall Grass and Brushland/Low Trees categories (7 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.