2018 MN DNR Lidar: Lake County, MN

Product: These lidar data are processed Classified LAS 1.4 files, formatted to 3041 individual 750 m x 750 m tiles; used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Geographic Extent: The central portion of Lake County in Minnesota, covering approximately 627 total square miles.

Dataset Description for the Original Data: The MNDNR Lake County 2018 LiDAR project called for the planning, acquisition, processing, and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.236 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.3. The data were developed based on a horizontal projection/datum of NAD 1983 2011 UTM Zone 15N, Meter and vertical datum of NAVD88 GEOID12B, Meter. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 3041 individual 750 m x 750 m tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 750 m x 750 m schema. Continuous breaklines were produced in Esri file geodatabase format.

Ground Conditions: LiDAR was collected in fall 2018, 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 14 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 70 independent accuracy checkpoints, 40 in Bare Earth and Urban landcovers (40 NVA points), 30 in Tall Weeds categories (30 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the Entwine Point Tiles (EPT) hosted by USGS on Amazon Web Services.

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 0.3 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.

Contract No. I6AAP-17; CONTRACTOR: Quantum Spatial, Inc.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Specification v1.3",

"ldrsens" : "Riegl 1560i",

"ldrmaxnr" : "unlimited",

"ldrnps" : "0.236",

"ldrdens" : "18.0",

"ldranps" : "0.236",

"ldradens" : "17.95",

"ldrfltht" : "1306",

"ldrfltsp" : "145",

"ldrscana" : "29",

"ldrscanr" : "41.5",

"ldrpulsr" : "193",

"ldrpulsd" : "3",

"ldrpulsw" : "0.24",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.18",

"ldrswatw" : "1448.0",

"ldrswato" : "55",

"ldrgeoid" : "GEOID 12B",

"ldrcrs" : "NAD 1983 2011 UTM Zone 15N, Meter"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "0",

"clsnva" : "0",

"clsnvan" : "0",

"clsvva" : "0",

"clsvvan" : "0"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld (ignore) points were identified in these files using the standard LAS

Withheld bit.",

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS

overlap bit.",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare-Earth Ground"

},

"lasclass" : {

"clascode" : "3",

"clasitem" : "Low Vegetation"

},

"lasclass" : {

"clascode" : "4",

"clasitem" : "Medium Vegetation"

},

"lasclass" : {

"clascode" : "5",

"clasitem" : "High Vegetation"

},

"lasclass" : {

"clascode" : "6",

"clasitem" : "Buildings"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "8",

"clasitem" : "Model Key Points"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "In-land Water"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "20",

"clasitem" : "Ignored Ground"

}

}}

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners.

Data is available online for bulk and custom downloads.

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

MicroStation Version 8; TerraScan Version 18; TerraModeler Version 18; GeoCue Version

2017.1.14.1; Esri ArcGIS 10.3; Global Mapper 19; RiProcess 1.8.5; Windows 10 Operating System

\\point_cloud\tilecls\*.las

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class.

USGS Determined Vertical Accuracy:

Tested NVA RMSEz = 5.7 cm

Tested 95th percentile value for VVA is : 21.76 cm

For more information see the USGS project report and the lidar report. The links to these reports are provided in the URL section of this metadata record.

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 the data pass

Non-Vegetated Vertical Accuracy specifications.

Data cover the entire area specified for this project.

Data is backed up to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS Entwine Point Tiles (EPT) hosted on Amazon Web Services (AWS) into the Digital Coast Data Access Viewer (DAV). The DAV accesses the point cloud as it resides on AWS under the usgs-lidar-public-container.