2017 USGS Lidar: Dane, La Crosse, Langlade and Sawyer Counties, WI

Four Wisconsin counties were collected in the USGS 2017 Statewide collect - Dane, La Crosse, Langlade, and Sawyer. Project areas covered approximately 1252, 486, 896, and 1360 square miles, including a 100 meter buffer around each 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 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 the NAD83(2011) Wisconsin county projection appropriate to each county, and vertical datum of NAVD88 - Geoid12B (Feet). Lidar data was acquired using the Leica ALS70 SN7161 Sensor. Acquisition occurred with leaves absent from deciduous trees, when no snow was present on the ground, and with rivers at or below normal levels.

Part of the Wisconsin statewide lidar coverage and the 3D Elevation Program's efforts to cover the nation with lidar.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

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

"ldrsens" : "ALS70_SN7161",

"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",

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

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "0"

},

"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

Dane County, WI

La Crosse County, WI

Langlade County, WI

Sawyer County, WI

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 61.

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 49.

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: 0.082 meters (0.264 survey feet), AccuracyZ at 95% confidence level, AccuracyZ at 95% confidence level, Test that produced the value:

Dane County: compiled to meet 0.196 meter accuracy at the 95 percent confidence level.

La Crosse County: 0.092 meters (0.301 survey feet) NVA at the 95 percent confidence level using 52 independent checkpoints located in the Bare Earth and Urban land cover categories.

Langlade County: 0.076 meters (0.249 survey feet) NVA at the 95 percent confidence level using 56 independent checkpoints located in the Bare Earth and Urban land cover categories.

Sawyer County: 0.080 meters (0.264 survey feet) NVA at the 95 percent confidence level using 69 independent checkpoints located in the Bare Earth and Urban land cover categories.

Weighted average excluding Dane County = 0.082 meters at the 95 percent confidence level.

Spatial consistency of coverage of the project area was maintained throughout the dataset.

Spatial consistency of coverage of the project area was maintained throughout the dataset.

Data is backed up to cloud storage.

Lidar was collected in 2017 for four counties in Wisconsin. USGS created Entwine Point Tile versions of the data (the sources) and NOAA is leveraging those data to generate custom products in the Digital Coast Data Access Viewer.