2018 NRCS Lidar: Calhoun, Clarendon and Orangeburg Counties, SC

The Project data set consists of a classified lidar point cloud The Geographical Extent of this dataset covers approximately 2215 square miles for the QL2 area covering Calhoun, Clarendon and Orangeburg counties in SC. The flight plan consisted of 201 survey lines and 3 control lines.

Ground Conditions: water at normal levels; no unusual inundation; no snow; leaf off

How the Withheld Points are Identified: Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

ANPS: 0.71 Meters

Tile Size: 5,000 US Feet

Spec: National Geospatial Program(NGP) Lidar Base Specification v1.3

LAS File Type: 1.4 type 6

The USGS/NGTOC and US Forest Service contracted Digital Aerial Solutions, LLC to obtain professional services related to the planning, acquisition and development of Light Detection and Ranging (Lidar) data and derivative products. The task order is for a QL2 Lidar survey to be collected over Calhoun, Clarendon and Orangeburg counties in SC. The deliverable products would be used by the USGS/NGTOC and US Forest Service for conservation planning, design, research, floodplain mapping, wetlands identification, dam safety assessments, hydrologic modeling, and other environmental purposes.

All Lidar data and associated products were acquired, calibrated, and used in the creation of Lidar derived products by Digital Aerial Solutions, LLC.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program(NGP) Lidar Base Specification v1.3",

"ldrsens" : "Leica ALS80 SN# 8137 and SN#8235",

"ldrmaxnr" : "Unlimited",

"ldrnps" : "0.52",

"ldrdens" : "3.64",

"ldranps" : "0.52",

"ldradens" : "3.64",

"ldrfltht" : "1655",

"ldrfltsp" : "155",

"ldrscana" : "38.0",

"ldrscanr" : "53.3",

"ldrpulsr" : "331.0",

"ldrpulsd" : "4",

"ldrpulsw" : "0.42",

"ldrwavel" : "1064",

"ldrmpia" : "2",

"ldrbmdiv" : "0.15",

"ldrswatw" : "1139.69",

"ldrswato" : "30",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid 12B"

},

"ldraccur" : {

"ldrchacc" : "0.64",

"rawnva" : "0.150",

"rawnvan" : "76",

"clsnva" : "0.087",

"clsnvan" : "76",

"clsvva" : "0.111",

"clsvvan" : "59"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld (ignore) points were identified in the 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" : "Undetermined/Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare earth"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridges"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "20",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "21",

"clasitem" : "Snow"

},

"lasclass" : {

"clascode" : "22",

"clasitem" : "Temporal Exclusion"

}

}}

None

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.

Inertial Explorer ver: 8.6; Leica CloudPro Ver:1.2.1; GeoCue Ver: 2014.1.21.4; Microstation V8i; Terresolid ver: 2015; LP360 ver: 2014.1.51.1; Arcmap ver: 10.4; Global Mapper ver: 16

Horizontal error in lidar derived elevation data is largely a function of positional error as derived from the Global Navigation Satellite System (GNSS), attitude (angular orientation) error (as derived from the INS) and flying altitude; and can be estimated based on these parameters. Quantitative value: 0.783, Test that produced the valued: This data set was produced to meet ASPRS “Positional Accuracy Standards for Digital Geospatial Data” (2014) for a 0.226 Meters RMSEx / RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy =+/- 0.783 Meters at a 95% confidence level Estimated LiDAR Horizontal Error Per Point.

Vertical Accuracy of the bare-earth lidar data was assessed and reported in accordance with the ASPRS Positional Accuracy Standards for Digital Geospatial Data; One-Hunderd Thirty-Five (135) surveyed points were measured for the purpose of assessing the accuracy of the SC East Central QL2 data (76 NVA + 59 VVA). Both data sets, Lidar and Digital Elevation Models (DEMs) have been tested for there individual vertical accuracy levels. The Lidar was tested by using interpolation while the DEMs where tested by extracting the elevation of a pixel containing the checkpoint. All DEM Vertical accuracy results are reported in the DEM Metadata reports while this project wide Metadata file is reporting the vertical accuracy results from the the source Lidar. Required Non Vegetated Vertical Accuracy (NVA): 0.196 Meters. Required Vegetated Vertical Accuracy (VVA): 0.294 Meters.

Classified LiDAR: Tested to be 0.087 meters NVA at 95-percent confidence level using RSME(z) x 1.9600 as defined by the National Standards for spatial Data Accuracy (NSSDA).

The root mean square error vertical (RMSEz) was computed to be 0.044 meters.

The NVA of the Classified LiDAR point cloud was calculated against TINs derived from the final calibrated and controlled swath data using 76 NVA checkpoints located in Bare Earth land cover class.

The raw LAS data files included 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 Fundamental Vertical Accuracy specifications. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique “NODATA” value. This value is identified in the appropriate location within the file header.

Aerial LiDAR data covers the entire 2,215 square mile Area of Interest intended for this project task. All LiDAR Point Cloud tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique “NODATA” value. This value is identified in the appropriate location within the file header. Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.