2021 USGS Lidar: South Central Illinois

Product: These lidar data are processed Classified LAS 1.4 files, formatted to individual 2000 US survey feet x 2000 US survey feet tiles; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: This project covers 17 counties in south central Illinois.

IL_SouthCentral_1 (Work Unit 216607) covering approximately 6109 square miles in the following counties: Clay, Effingham, Fayette, Jefferson, Macon, Marion, Moultrie, Richland, Shelby, Vermillion

IL_SouthCentral_2 (Work Unit 226708) covering approximately 3260 square miles in the following counties: Bond, Calhoun, Clinton, Jackson, Jersey, Perry, Washington

Dataset Description of the Original Data: USGS_IL_SouthCentral Illinois 2021 Lidar project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.5 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 2020 rev A. The data was developed based on a horizontal projection/datum of NAD83(2011), State Plane Illinois East and West, US survey feet, and a vertical datum of NAVD88 (GEOID18), US survey feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to individual 2000 US survey feet x 2000 US survey feet tiles, tiled Intensity Imagery, and tiled bare earth DEMs; all tiled to the same 2000 US survey feet x 2000 US survey feet schema. Lidar point cloud LAS files are created for each tile in the tiling schema in which there is reflected photonic energy. No LAS files are created for tiles in which there is total absorption of photons, such as tiles consisting of all water and in which photonic energy is absorbed. Intensity Images are created for each tile in the tiling schema in which there is reflected photonic energy. No intensity tiles are created for tiles in which there is total absorption of photons, such as tiles consisting of all water and in which photonic energy is absorbed.

Ground Conditions: Lidar was collected in spring 2021, 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, Subcontractor, Prairie Engineers established ground control points that were used to calibrate the lidar to known ground locations established throughout the USGS_IL_SouthCentral Illinois project area. Additional independent accuracy checkpoints, in Bare Earth and Urban landcovers, tall Grass/tall weeds/crops, Brush lands/short trees, Forested categories were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

To acquire QL2+ lidar detailing surface elevation data, and vegetation to support the Federal Emergency Management (FEMA) Risk Mapping, Assessment, and Planning (MAP) program, the National Resources Conservation Service (NRCS) high resolution elevation enterprise program, the Illinois State Geological Survey's Height Modernization Program, Land Stewardship (IDALS) Illinois Flood Plain program, and the 3DEP mission. 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 this lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 2 US survey feet cell size. These lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

USGS Contract No. 140G0221F0069 CONTRACTOR: Aerial Services, Inc. (ASI) served as the prime contractor for this project. In addition to project management, ASI was responsible for LiDAR acquisition and calibration for a 934 square mile area of the farthest northeast section of this USGS_IL_SouthCentral_1_2021 project. ASI was responsible for producing LiDAR products; Digital Elevation Model (DEM), Intensity Imagery, and quality assurance for the entire IL South Central project. Subcontractor: Aerial Surveys International, LLC was responsible for LiDAR acquisition and calibration for a 4,429 square mile area of the central portion of the USGS_IL_SouthCentral_1_2021 project. Subcontractor: SurvTech Solutions was responsible for LiDAR acquisition and calibration of 579 square miles of the southern section of the USGS_IL_SouthCentral_1_2021 project area. SurvTech Solutions manually performed bare earth cleanup and collected hydro for the far northeastern portion of this project area that was acquired by ASI. Subcontractor: Ayres Associates manually performed bare earth cleanup, and collected hydro on the remaining 5007 square mile area of the USGS_IL_SouthCentral_1_2021 project area. All follow-up processing was completed by the prime contractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v2020, Revision A",

"ldrsens" : "Reigl LMS-Q1560",

"ldrmaxnr" : "4",

"ldrnps" : "0.5",

"ldrdens" : "4",

"ldranps" : "0.5",

"ldradens" : "4",

"ldrfltht" : "1278",

"ldrfltsp" : "150",

"ldrscana" : "58.52",

"ldrscanr" : "107",

"ldrpulsr" : "400",

"ldrpulsd" : "2.5",

"ldrpulsw" : "0.75",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "1432",

"ldrswato" : "20",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid18"

},

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v2020, Revision A",

"ldrsens" : "Optech Galaxy T2000",

"ldrmaxnr" : "8",

"ldrnps" : "0.5",

"ldrdens" : "4",

"ldranps" : "0.5",

"ldradens" : "4",

"ldrfltht" : "2134",

"ldrfltsp" : "160",

"ldrscana" : "32",

"ldrscanr" : "92",

"ldrpulsr" : "800",

"ldrpulsd" : "1.25",

"ldrpulsw" : "0.37",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.16",

"ldrswatw" : "1553",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid18"

},

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v2020, Revision A",

"ldrsens" : "Optech T2000",

"ldrmaxnr" : "8",

"ldrnps" : "0.5",

"ldrdens" : "4",

"ldranps" : "0.5",

"ldradens" : "4",

"ldrfltht" : "2500",

"ldrfltsp" : "160",

"ldrscana" : "32",

"ldrscanr" : "92",

"ldrpulsr" : "800",

"ldrpulsd" : "1.25",

"ldrpulsw" : "0.24",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.16",

"ldrswatw" : "1434",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid18"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "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" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

},

"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.

Track’Air; Topoflight ; Optech’s FMS; Trimble CenterPoint® RTX™, POSPac PP-RTX, GNSS, Applanix’s POSPAC MMS version 8.4.7284.36831, Optech’s LMS ; MARS 8; RIPROCESS; BayesMap-StripAlign; MicroSatation Connect Update 16 - version 10.16.00.80; TerraSolid TerraMatch version020.003,TerraModel version 021.004, TerraScan version 021.005; Windows 10 Operating \\server\directory path\*.las 3.63TB

IL_SouthCentral_1:

The Optech Galaxy Prime data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 28.75 (cm) RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 56.35 cm at a 95% confidence level.

IL_SouthCentral_2:

The Optech Galaxy Prime data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 32.72 (cm) RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 64.13 cm at a 95% confidence level.

USGS Determined Vertical Accuracy:

Tested NVA RMSEz = 4.3 cm

Tested 95th percentile value for VVA is : 16.57 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 data passes Non-Vegetated Vertical Accuracy specifications.

Data covers 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.