2020 USGS Lidar DEM: Savannah Pee Dee, SC

Product: Lidar based digital elevation model (DEM) data tiles for ground classified points.

Geographic Extent: Approximately 21,453 square miles across South Carolina;

Block 1 (Lot 6 QL2) - approximately 3,583 square miles in Anderson, Cherokee, Greenville, Laurens, Newberry, Oconee, Pickens, Spartanburg, and Union counties

Block 2 (Lot 7 QL1) - approximately 950 square miles in Greenville and Lexington counties

Block 3 (Lot 7 QL2) - approximately 3435 square miles in Abbeville, Aiken, Anderson, Edgefield, Greenwood, Laurens, McCormick, Newberry, Oconee, and Saluda counties

Block 4 (Lot 8 QL1) - approximately 135 square miles in Aiken and Edgefield counties

Block 5 (Lot 8 QL2) - approximately 5,775 square miles in Aiken, Allendale, Bamberg, Barnwell, Calhoun, Chester, Chesterfield, Clarendon, Colleton, Edgefield, Fairfield, Hampton, Kershaw, Lancaster, Lee, Lexington, McCormick, Newberry, Orangeburg, Richland, Saluda, and Sumter counties

Block 6 (Lot 9 QL2) - approximately 7,255 square miles in Bamberg, Beaufort, Berkeley, Charleston, Chesterfield, Clarendon, Colleton, Darlington, Dillon, Dorchester, Florence, Georgetown, Hampton, Horry, Jasper, Kershaw, Lee, Marion, Marlboro, Orangeburg, Sumter, and Williamsburg counties

Block 7 (Lot 9 QL1) - approximately 689 square miles in Beaufort, Berkeley, Charleston, Colleton, Darlington, Dorchester, Florence counties

Dataset Description: The SC Savannah Pee Dee 2019 B19 lidar project called for the planning, acquisition, processing, and production of derivative products of QL 1 and QL2 lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 and 0.71 meters. Project specifications were based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3. The data was developed based on a horizontal datum/projection of NAD83 (2011) State Plane South Carolina (FIPS 3900) International Feet (EPSG 6570), and a vertical datum of NAVD88 (GEOID18) US Survey Feet. Lidar data was delivered as processed LAS 1.4 files formatted to individual 5,000-Int'l. foot x 5,000-Int'l. foot tiles.

Ground Conditions: Lidar was collected January through March 2020 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, Woolpert established ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. Additional independent accuracy checkpoints were collected and used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

This project will support the 3DEP mission, the Natural Resources Conservation Service (NRCS) high resolution elevation enterprise program, and the Federal Emergency Management Agency (FEMA) Risk Mapping, Assessment and Planning (MAP) program, as well as many South Carolina state and local agencies.

USGS Contract No. G16PC00022, Task Order No. 140G0219F0339. Contractor: Woolpert. Sub-contractors: GRW, Inc., SurvTech Solutions, Florabama Geospatial Solutions, LLC (FGS).

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS NGP Base Specifications v1.3",

"ldrsens" : "Leica Terrain Mapper",

"ldrmaxnr" : "15",

"ldrnps" : "0.71",

"ldrdens" : "2",

"ldranps" : "0.71",

"ldradens" : "2",

"ldrfltht" : "2500",

"ldrfltsp" : "150",

"ldrscana" : "40",

"ldrscanr" : "90",

"ldrpulsr" : "600",

"ldrpulsd" : "5",

"ldrpulsw" : "2.5",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.25",

"ldrswatw" : "1820",

"ldrswato" : "25",

"ldrgeoid" : "GEOID18"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "0"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Geometrically unreliable points were identified using a combination of automated and manual techniques and subsequently classified as high or low noise and given the standard 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 not classified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge decks"

},

"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.

Microsoft Windows 10 Version 1803 (Build 17134.1304); ArcMap 10.7; ArcCatalog 10.7; TerraScan ver. 20; TerraModeler ver. 20; LP360 v2019.1.30.4.

Blocks 1, 3, 5, 6

The data sets was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 18.6 cm RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 45.5 cm at a 95% confidence level.

Blocks 2, 4, 7

The data sets was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 14.5 cm RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 35.5 cm at a 95% confidence level.

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:

NVA = 8.7 cm at 95% confidence level (4.4 cm RMSEz)

VVA = 20.18 cm at 95th Percentile

Please refer to the USGS Work Package report (link provided in URL section of this metadata record) for more information.

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.

Data covers the entire area specified for this project.

Data is backed up to tape and to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS Cloud Optimized GeoTIFF files hosted on Amazon Web Services (AWS) into the Digital Coast Data Access Viewer (DAV). The DAV accesses the DEM as it resides on AWS under the prd-tnm bucket.