Data Management Plan

These files contain topographic lidar data classified as ground (2) and unclassified (1) in accordance with the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards. These data were collected by the Compact Hydrographic Airborne Rapid Total Survey (CHARTS) system along the coast of Maryland. CHARTS integrates topographic and bathymetric lidar sensors, a digital camera and a hyperspectral scanner 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). The topographic lidar sensor has a pulse repetition rate of 9 kHz at 1064 nm (near-infrared wavelength). The bathymetric lidar sensor has a pulse repetition rate of 1 kHz at 532 nm (green wavelength). Native lidar data is not generally in a format accessible to most Geographical Information Systems (GIS). Specialized in-house and commercial software packages are used to process 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 sub-divided into a series of LAS files, each covering approximately 5 kilometers of shoreline. The format of the file is LAS version 1.2.

In addition to these lidar point data, the bare earth Digital Elevation Models (DEM) created from the lidar point data are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

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 9kHz, bathymetric lidar data at 1kHz 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 the TerraScan V11 module within MicroStation V8.0. The resulting LAS files are thinned to eliminate duplicate points. A customized classification macro is used to distinguish ground points (2) and unclassified points (1). The classification results are QC'd 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 points are exported to an ASCII file containing the following fields: longitude, latitude, elevation (orthometric), intensity, classification, mirror angle, time (GPS time), number of echos, and echo number. The ASCII file is converted to LAS with the txt2las code from LAStools. The resulting topographic las files and bathymetric ASCII were then loaded into Geocue to produce one single las file representing both valid bathymetry and topography in ellipsoid.
• 2018-12-07 00:00:00 - The NOAA Office for Coastal Management (OCM) received 9 files in laz 1.2 format. The files contained lidar intensity and elevation measurements for the project area. Horizontal positions were provided in geographic coordinates, referenced to the North American Datum of 1983. Vertical positions were provided in ellipsoid elevations and in meters. OCM performed the following processing for data storage and Digital Coast provisioning purposes: 1. The LAStools software scripts lasinfo and lasvalidate were run on the laz files to check for errors. 2. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 3. The LAStools software script las2las was run to convert the gps seconds of the week time to adjusted gps time. 4. Internal OCM scripts were run on the laz files to assign the geokeys, to sort the data by gps time and zip the data to database and to http.

Data is available online for bulk and custom downloads.