2016-2017 NCEM NCDOT USGS Lidar: Phase Four Counties in North Carolina

The data set was collected specific to the 2016 Phase Four project area consisting of 20 North Carolina counties. lidar data for the project and the validation site was collected by a single aerial vendor on ESP team between February 27, 2016 and April 17, 2016 and between December 9, 2016 and February 21 of 2017 using Geiger-mode Avalanche Photodiode (GmAPD) sensors. The aerial vendor on the ESP team was Harris Corporation (Harris).Two GmAPD (Geiger-mode) sensors (serial numbers 002 and 003) were used for the data collection of lidar data at a 0.35 meter nominal post spacing (NPS). The following counties or portions of counties were collected in the February through April, 2016 mobilization: Alleghany, Stokes, Surry, Cleveland, Gaston, Mecklenburg, Cabarrus, Stanly, Union, and Anson. The following counties or portions of counties we collected in the December, 2016 through February, 2017 mobilization: Cleveland, Gaston, Mecklenburg, Cabarrus, Stanly, Wilkes, Yadkin, Forsyth, Alexander, Catawba, Iredell, Davie, Rowan, and Davidson. All data was collected during leaf-off conditions. Ground survey support for the project included the establishment of GPS base stations and the collection of control points used for calibration. All data was delivered in the North Carolina State Plane Coordinate System, with a horizontal datum of NAD83 (2011), vertical datum of NAVD88 (Geoid 12B), in US Survey Feet. Data was delivered tiled to a 2,500 foot by 2,500 foot tiling scheme unless otherwise specified in this product description. All lidar was delivered in LASer (LAS) version 1.4 standard format. All lidar and derivative products for this project met the specifications stipulated in Delivery Order 22, the NC Lidar Standard, and the USGS minimum standards for QL1 lidar data. This project was a joint effort between NC Emergency Management, NC Geodetic Survey, and the NCDOT. The following people served as the main representatives for each stakeholder: NC Emergency Management- Hope Morgan (primary contact) and John Dorman; NC Geodetic Survey- Gary Thompson and Watson Ross; NCDOT- Keith Johnston and Marc Swartz, and the United States Geological Survey (USGS).

This metadata 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. At the time of ingest into the DAV (August 2020), that data was missing Lincoln, Cabarrus, and Stanly Counties from the full Phase IV data set. Those counties have been added for DAV processing (January, 2022), but not as EPT.

The purpose of this project was to update existing lidar data, originally collected between 2000 and 2005, with more accurate and clearly defined lidar data utilizing the latest in sensor technology. Although created for the North Carolina Floodplain Mapping Program for specific use in the engineering aspects of floodplain delineation, the data were also developed to address the elevation data requirements of the broader geospatial community. The North Carolina Floodplain Mapping Program was established in response to the extensive damage caused by Hurrican Floyd in 1999.

NCEM GTM Contract No. 286-000030 ESP CONTRACTOR: ESP Associates SUBCONTRACTORS: Harris Corporation, Surdex Corporation. Lidar data were acquired and calibrated by Harris Corporation. All follow-on processing was completed by the prime contractor and Surdex Corporation.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "North Carolina Emergency Management Hybrid Specifications 2016",

"ldrsens" : "IntelliEarth GmAPD lidar",

"ldrmaxnr" : "1",

"ldrnps" : "0.35",

"ldranps" : "8",

"ldrdens" : "8",

"ldradens" : "8",

"ldrfltht" : "5182",

"ldrfltsp" : "220",

"ldrscana" : "15",

"ldrscanr" : "16",

"ldrpulsr" : "50",

"ldrpulsd" : "0.5",

"ldrpulsw" : "0.15",

"ldrwavel" : "1064",

"ldrmpia" : "0",

"ldrbmdiv" : "0.035",

"ldrswatw" : "2390",

"ldrswato" : "55",

"ldrcrs" : "NAD_1983_2011_StatePlane_North_Carolina_FIPS_3200_Feet",

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

},

"ldraccur" : {

"ldrchacc" : "0.30",

"rawnva" : "0.142",

"rawnvan" : "1634",

"clsnva" : "0.142",

"clsnvan" : "1634"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

"lasolap" : "Standard LAS overlap bit not used due to 55 percent overlap project design",

"lasintr" : "5",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "3",

"clasitem" : "Low Vegetation 0.5 to 3 feet"

},

"lasclass" : {

"clascode" : "4",

"clasitem" : "Medium Vegetation 3 to 10 feet"

},

"lasclass" : {

"clascode" : "5",

"clasitem" : "High Vegetation 10 to 220 ft"

},

"lasclass" : {

"clascode" : "6",

"clasitem" : "Building 800 square feet or larger, automated filter"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise, Low"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Breakline Proximity"

},

"lasclass" : {

"clascode" : "11",

"clasitem" : "Noise, High"

},

"lasclass" : {

"clascode" : "13",

"clasitem" : "Roads, NCDOT assets"

},

"lasclass" : {

"clascode" : "14",

"clasitem" : "Bridges, NCDOT assets"

}

}}

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.

MicroStation Connect Version 10; TerraScan Version 17; ESRI ArcGIS 10.4.1, Windows 7 Operating System, ESP Analyst, ESP Utilities

The project specifications require that Non-Vegetated Vertical Accuracy (NVA) and Vegetated Vertical Accuracy (VVA) be computed for calibrated and classified lidar point cloud files. The required accuracy (ACCz) is: 18.13 cm at a 95% confidence level for NVA, derived according to NSSDA, i.e., based on RMSE (z) of 9.25 cm in the bare earth? and "urban" land cover classes. The NVA was tested with 1634 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the classified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 18.13 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.Quantitative value: 0.142, Test that produced the value: Tested 0.142 meters NVA at a 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA). The NVA of the classified lidar point cloud files was calculated against TINs derived from the final calibrated and controlled data using 1634 independent NVA checkpoints.

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 point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

ESP Assocites tested the classified LAS files for both vertical and horizontal accuracy. All data covers the project area, tile to tile with no gaps or no data areas exceeding specifications

Data is backed up to tape and to cloud storage.

North Carolina Phase 4 lidar was ingested into the Data Access Viewer for custom product generation by leveraging USGS hosted Entwine Point Tiles and obtaining three counties missing from EPT in LAZ format.