2017 USGS QL2 Lidar: Forest County, WI

The Forest County lidar project area covers approximately 1056 square miles which includes a 100 meter buffer around the county boundary. The lidar data was acquired at a nominal point spacing (NPS) of 0.7 meters and a single swath nominal point density (NPD) of 2.0. Project specifications are based on Forest County requirements and on the U.S. Geological Survey National Geospatial Program LiDAR Base Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83(2011) / Forest County (ftUS) (EPSG Code: 7606), and vertical datum of NAVD88 - Geoid12B (Feet). LiDAR data was acquired using the Leica ALS70 SN7161 and SN7178 sensors from April 22, 2017 through April 25, 2017 in seven total lifts. Acquisition occurred with leaves absent from deciduous trees, when no snow was present on the ground, and with rivers at or below normal levels.

Data were converted to ellipsoid heights in meters and geographic coordinates for ingest into the Digital Coast Data Access Viewer. Further conversion may be done there using this metadata as a template. There may also be an orthometric download available (see Distribution section).

This data, along with its derivatives, is the result of a countywide elevation mapping with cooperative partnerships from Forest County, Wisconsin DOA, and the USGS 3DEP program. This data was produced from lidar data collected in April 2017, which was processed and delivered in 2018.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Specification v1.2",

"ldrsens" : "ALS70_SN7161 and SN7178",

"ldrmaxnr" : "4",

"ldrnps" : "0.72",

"ldrdens" : "2.99",

"ldranps" : "0.72",

"ldradens" : "2.99",

"ldrfltht" : "1800",

"ldrfltsp" : "150",

"ldrscana" : "40.0",

"ldrscanr" : "53.4",

"ldrpulsr" : "302.6",

"ldrpulsd" : "4",

"ldrpulsw" : "0.48",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.22",

"ldrswatw" : "1310.29",

"ldrswato" : "30",

"ldrcrs" : "NAD83(2011) / Forest County (ftUS) (EPSG Code: 7606)",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "n/a",

"rawnva" : "0.110",

"rawnvan" : "59"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "n/a",

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS overlap bit.",

"lasintr" : "11",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth"

},

"lasclass" : {

"clascode" : "5",

"clasitem" : "High Vegetation"

},

"lasclass" : {

"clascode" : "6",

"clasitem" : "Building"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

Distributor assumes no liability for misuse of data.

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 or 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.

The project specifications require the vertical accuracy of the LiDAR data to be calculated and reported according to Non-vegetated Vertical Accuracy (NVA) and Vegetated Vertical Accuracy (VVA) classifications.

The required NVA for this project is 19.6 cm (0.643 survey feet) calculated at the 95 percent confidence level (AccuracyZ). The 95 percent confidence level statistic is derived according to National Standards for Spatial Data Accuracy (NSSDA) methodologies using RMSEz * 1.9600. This requirement is for the vertical accuracy testing of the raw swath lidar data and the derived digital elevation model (DEM). The AccuracyZ statistic is assessed and reported using National Digital Elevation Program (NDEP)/ASPRS Guidelines. The minimum required number of NVA checkpoints for this project area is 58.

The required VVA for this project is 29.4 cm (0.965 survey feet) calculated at the 95th percentile derived according to ASPRS Guidelines, Vertical Accuracy Reporting for Lidar Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This requirement is for the vertical accuracy testing of the derived digital elevation model (DEM). The minimum required number of VVA checkpoints for this project area is 47.

The NVA (bare earth and urban area land cover classes) and VVA (tall weeds, forested, and swamp land cover classes) checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the hydro flattened raster DEM were measured for the x,y location of each check point. Elevations interpolated from the hydro flattened raster DEM surface were then compared to the elevation values of the surveyed control points.

Quantitative value: 0.110 meters (0.364 survey feet), AccuracyZ at 95% confidence level, AccuracyZ at 95% confidence level, Test that produced the value: 0.110 meters (0.364 survey feet) NVA at the 95 percent confidence level. The NVA of the raw swath was calculated using 59 independent checkpoints located in the Bare Earth and Urban land cover categories.

Spatial consistency of coverage of the Forest Co. QL2 LiDAR (2017-18) project area was maintained throughout the dataset.

Spatial consistency of coverage of the Forest Co. QL2 LiDAR (2017-18) project area was maintained throughout the dataset.

Data is backed up to cloud storage.