Data Management Plan

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.

Lineage Statement:
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.

Process Steps:

• 2017-01-01 00:00:00 - LAS Point Classification: The point classification is performed as described below. The bare earth surface is then manually reviewed and edited using TIN visualization and profiles to ensure correct classification on the Class 2 (Ground) points as well as the other classifications required by NCEM. After the bare-earth surface is finalized, it is then used to generate all hydro-breaklines through heads-up digitization in a 3D environment for all rivers equal to or larger than 100 feet in width and all closed water bodies equal to or greater than 2 acres. Island equal or greater than 1 acre are mapped are included. All ground (Class 2) lidar data inside of the Lake Pond and Double Line Drain hydro flattening breaklines were classified to water (Class 9) using ESP Utilities. A buffer of 1 foot was also used around each hydro-flattened feature to classify ground (Class 2) points within the buffer to breakline proximity (Class 10). All Lake Pond Island and Double Line Drain Island features were reviewed in ESP Analyst and checked to ensure that the ground (Class 2) points were reclassified to the correct classification after the automated classification was completed. Overlap data was not processed as Geiger mode lidar is flown at a 55 percent overlap with a Palmer scanner. Road polygons derived from heads-up digitization from aerial imagery and the lidar were derived for only state-maintained roads per the latest available road database from the North Carolina Department of Transportation. These polygons were then used to classify all ground points with the road edges to roads (Class 13). All remaining classifications required by NCEM such as buildings (Class 6) and vegetation strata (Classes 3, 4, and 5) were derived using automated filters in Terrascan then checked for gross errors and review to ensure that a 98 percent confidence level in classification was met. All data was manually reviewed and any remaining artifacts in the ground (Class 2) removed using functionality provided by ESP Analyst. ESP Analyst was used as a final check of the bare earth dataset. ESP Utilities was then used to create the deliverable industry-standard LAS files for both the All Point Cloud Data. ESP Utilities was used to verify full LAS header and projection information.
• 2019-01-01 00:00:00 - Original point clouds in LAS/LAZ format were restructured as Entwine Point Tiles and stored on Amazon Web Services. The data were reprojected horizontally to WGS84 Web Mercator (EPSG 3857). Vertically the data was converted to meters and no changes were made to the vertical datum (NAVD88 GEOID12B; EPSG 5703). (Citation: LAS point cloud on AWS)
• 2020-07-30 00:00:00 - References to the entwine point tiles and data reports were ingested into the Digital Coast Data Access Viewer. No changes to the data were made at this point. The Data Access Viewer will access the point cloud as it resides on AWS under the usgs-lidar-public container. (Citation: Entwine Point Tiles on AWS)
• 2022-01-19 00:00:00 - The three counties missing from the USGS EPT holdings were downloaded from the USGS RockyWeb holdings. These were converted to geographic coordinates (NAD83 2011) and vertical meters. The vertical datum was left as NAVD88 Geoid12B to match the USGS EPT holdings. This allows the Data Access Viewer to combine them. (Citation: USGS Point Cloud)

Data is available online for bulk or custom downloads

Data is backed up to tape and to cloud storage.