2013 NRCS Lidar: Logan County, IL

Task Order:G13PD00885 Contract ID: G10PC00025

This dataset is LiDAR point cloud data and derivative models of Logan County, Illinois. The area of acquisition is approximately 618 square miles (1600 square kilometers). This dataset consists of LiDAR LAS swath files and tiled LAS files. Tiled LAS files contain LiDAR point information which has been calibrated, controlled, and classified. Tiled LAS and derived data models are named according to a tiling scheme in accordance with the conventions of the U.S. National Grid, using the coordinates at the SW corner of the tile as the tile name.

Quantum Spatial Project No: 1130905

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.

LiDAR data collection is to produce high accuracy models of the Logan County, Illinois in accordance with requirements outlined in the Task Order Agreement.

The raw LiDAR point cloud data is used to create surface models as requested; classified LiDAR LAS files, bare-earth Digital Elevation Models (DEM), Intensity raster of first return, shapefiles of breaklines representative of surface hydro features.

Project data includes an area in the northeast of Logan county, from Oran into Chester Townships, where LiDAR data was collected at 8 points per meter. The data is incorporated with the county wide data set which is at 4 points per meter.

8 point per meter collection rate:

Average Point Spacing 0.5 meters

Average Point Density 8.36 meters

Flying Height AGL 775 meters

Recommended Ground Speed 150 knots

Field of View (FOV) 36 degrees

Scan Rate Setting used 56 Hz

Laser Pulse Rate used 33.5 Hz

Full Swath Width 1105 meters

Minimum Sidelap 19 degrees

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS NGP Base Specification v1",

"ldrsens" : "Leica ALS70 sensor SN7220",

"ldrmaxnr" : "4",

"ldrnps" : "0.5",

"ldrdens" : "4.20",

"ldrfltht" : "1475",

"ldrfltsp" : "150",

"ldrscana" : "40",

"ldrscanr" : "53.4",

"ldrpulsr" : "358",

"ldrpulsd" : "4",

"ldrpulsw" : "NA",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.15",

"ldrswatw" : "1105.16",

"ldrswato" : "12",

"ldrcrs" : "NAD_1983_2011_StatePlane_Illinois_West_FIPS_1202_Ft_US",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12A"

},

"ldraccur" : {

"ldrchacc" : " 0.1",

"rawfva" : "0.107",

"clsfva" : " 0.106",

"clscva" : "0.1350",

"clssvas" : {

"svalctyp" : "Urban",

"svavalue" : "0.0923"

},

"clssvas" : {

"svalctyp" : "Open Terrain",

"svavalue" : "0.0990"

},

"clssvas" : {

"svalctyp" : "Tall Grass/Agriculture",

"svavalue" : "0.1267"

},

"clssvas" : {

"svalctyp" : "Brush/Scrub/Shrub",

"svavalue" : "0.1783"

},

"clssvas" : {

"svalctyp" : "Woods/Forest",

"svavalue" : "0.1338"

}

},

"lasinfo" : {

"lasver" : "1.2",

"lasprf" : "1",

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

",

"lasolap" : " To maintain high point density overage points were not indicated by class

",

"lasintr" : "8-bit",

"lasclass" : {

"clascode" : "0",

"clasitem" : "Never Processed"

},

"lasclass" : {

"clascode" : "1",

"clasitem" : "Undetermined/Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare-earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "All noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored ground"

}

}}

In no event shall the creators, custodians, or distributors of these data be liable for any damages arising out of its use, or from the inability of the customer to use these data for their intended application.

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.

ALS Post Processor 2.75 Build#25; GeoCue Version 13.1.45.1; Windows XP Operating System

Vertical accuracy assessment is conducted by comparing ground survey check point z values to processed LiDAR data z values by horizontal proximity. Differences in z values are calculated to express an RMSEz value.

The Fundamental Vertical Accuracy (FVA) of the LAS data achieved 10.7 cm at a 95% confidence level with an RMSE of 5.45 cm utilizing twenty-six (26) Open Terrain ground survey check points compared to a Digital Elevation Model (DEM) of the LiDAR ground points.

These data files include all data points collected.

No points have been removed or excluded.

The raw point cloud is of good quality and data passes Fundamental 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 Tile (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.