Data Management Plan

These files contain rasterized topographic lidar elevations generated from returns classified as ground (2). These data were collected by the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system along the coast of North Carolina. CHARTS integrates topographic and bathymetric lidar sensors, a digital camera and a hyperspectral imager on a single remote sensing platform for use in coastal mapping and charting activities. Data coverage generally extends along the coastline from the waterline inland 500 meters (topography) and offshore 1,000 meters or to laser extinction (bathymetry). Native lidar data is not generally in a format accessible to most Geographic Information Systems (GIS). Specialized in-house and commercial software packages are used to processes the native lidar data into 3-dimensional positions that can be imported into GIS software for visualization and further analysis. The 3-D position data are used to generate a series of gridded file products, with each covering approximately 5 kilometers of shoreline. The grid file index is provided by the shape file, "nc_boxes.shp", and the numbers used to identify files are in the "Box" field of the shape file. The data file naming convention is based on the year, project, area name, "Box" number and product type. An example file name is "2010_NCMP_NC_28_BareEarth_1mGrid.tif", where 2010 is the year of data collection, NCMP is the project under which data were collected, NC is the area of data collection, 28 is the "Box" number and "BareEarth_1mGrid" is the product.

Lineage Statement:
The USACE collected, processed, and provided the data to the NOAA Office for Coastal Management (OCM). OCM received the data and processed it to be available for custom download from the Data Access Viewer (DAV) and for bulk download from https.

Process Steps:

• These data were collected using the CHARTS system. It is owned by the Naval Oceanographic Office and operated through contract. The system collects topographic lidar data at 9 kHz, bathymetric lidar data at 1 kHz and RGB imagery at 1Hz. A CASI-1500 hyperspectral line scanner is integrated with the system as well. Aircraft position, velocity and acceleration information are collected through a combination of Novatel and POS A/V 410 equipment. All raw data streams are transferred to the office for downloading and processing in SHOALS GCS software. Aircraft position data are processed using POSPac software and the results are combined with the lidar data to produce 3-D positions for each lidar shot. Upon inspection and QA/QC in the software packages Fledermaus and PFM_ABE, anomalous data are flagged as invalid. PFM_ABE's chartsLAS module then converts all valid data from ellipsoid to orthometric heights based on the NGS' GEOID03 model and exports topographic data as a series of LAS files with a single file per flightline per 5km box.
• The flightline LAS files are imported into GeoCue V7.0.34, which is a geospatial workflow production and management software tool employed by JALBTCX to perform and monitor production of data products. Upon import into GeoCue, the flightline LAS files are divided into a series of boxes, each of which are 1500 meters in length and width. To each box is assigned a customized classification macro, built upon the TerraScan V10 module within Microstation V8.0 that distinguishes ground points (2) and unclassified points (1). The macro is executed for all boxes within GeoCue. Upon completion of all boxes the classification results undergo quality control, and any misclassified points are manually edited. In areas of dense vegetation the bare ground points might be incorrectly classified due to the inability of the laser to penetrate the canopy and reach the bare ground. In these areas, JALBTCX defaults to the algorithm’s “ground” surface instead of manually reclassifying those points. The final classification results are comprised of individual lidar points with classifications of ground (2) or unclassified (1). They are partitioned into a series of 5km delivery boxes, one Classified LAS file per 5km box.
• The points classified as ground in the Classified LAS files are exported from TerraScan V10 and converted to a grid by generating a Triangulated Irregular Network (TIN) and the extracting the grid node elevations from the TIN surface. The origin point of the grid is located at a horizontal position whose value is evenly divisible by the 1m grid resolution such that rasters from subsequent surveys have common cell boundaries. JALBTCX uses Quick Terrain Modeler V7.1.1 to perform this operation utilizing the following key parameters; “Max Sample Excursion 50,” “Max Triangle Side 100,” “Smoothing filter Level 4 with a Max Roughness 2, and "Tiling Settings Snap to Grid (Expand).” The grid is exported from Quick Terrain Modeler as an ESRI ASCII Z grid file. Utilizing an in-house python script within ESRI ArcMapV9.3, the ASCII Z grid file is converted to a tiff-format raster file whose projection is defined as “The North American Datum of 1983.”
• 2022-03-09 00:00:00 - The NOAA Office for Coastal Management (OCM) received GeoTiff format files from USACE JALBTCX for the NC project area. The bare earth raster files were at a 1 m grid spacing. The data were in geographic NAD83 coordinates and NAVD88 (Geoid03) elevations in meters. OCM assigned the appropriate EPSG codes (Horiz - 4269, Vert - 5703) and copied the raster files to https for Digital Coast storage and provisioning purposes.

Data is available online for bulk and custom downloads.