Data Management Plan

Fugro was contracted in July 2017 by the State of Maine Department of Marine Resources (SMDMR), Maine Coastal Program (MCP), and the NOAA Office for Coastal Management (OCM) to conduct an Airborne LiDAR Bathymetry (ALB) survey in the vicinity of Blue Hill Bay in Maine, and to deliver fully processed and verified hydrographic survey data.The ALB survey was conducted with the SHOALS-1000T and Riegl VQ-820-G lidar systems in a concurrent acquisition. The SHOALS system, with a high power laser, provided the better probability for deep sounding detections at a reduced point density (about 0.15 pts/m2); whilst the Riegl VQ-820-Q provided high density coverage (up to 8.5 pts/m2) but at reduced depth detection.

This metadata record describes the topographic and bathymetric LiDAR elevations generated from data collected with the Riegl VQ-820-Q LiDAR system along Blue Hill Bay on the coastline of Maine. These files contain topographic and bathymetric LiDAR elevations generated from data collected with the Riegl VQ-820-G LiDAR system along Blue Hill Bay on the coastline of Maine. Data were collected by Fugro for NOAA OCM. The Riegl VQ-820-G system is a a bathymetric LiDAR sensor for use in coastal mapping and charting activities because the laser's ability to penetrate the water column and detect targets up to 1 time the Secchi disk depth. Survey coverage is based on a delimiting polygon provided by NOAA OCM, which envelopes the area between the 0 m contour (NAVD88) down to approximated -10 meters. Riegl VQ-820-G data were processed on Riegl RiProcess software for: point cloud generation, boresight calibration, water surface classification and modeling, refraction correction; and exported with a minimal classification LAS format v1.4 for delivery. Additional classification was performed after delivery to extract ground and bathymetric points.

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.

A link to custom download the concurrently collected topographic and bathymetric data (collected with the SHOALS-1000T lidar system) is provided in the URL section of this metadata record.

Process Steps:

• The airborne raw files from the VQ-820-G sensor are downloaded into RIEGL LMS RiProcess version 1.8.3. The system collects bathymetric LiDAR data at 520 kHz Pulse Repetition Rate for an approximated point density of 8.5 pts/m2 at 400 m altitude (AGL) and 100 kts (speed over ground). Aircraft position, velocity, angular and acceleration information collected with an Applanix POS AV 510 v6 equipment were processed using Applanix POSPac v 7.1 software to produce a Smoothed Best Estimate Trajectory (SBET) solution file that is used by RiProcess to produce 3D positions for each LiDAR shot (point clouds). The RiProcess process also produced the automated and semi-automated clasification of water surface points to generate a water surface model for refraction correction of all lidar points underwater. Point clouds data was exported to LAS format were additional QC reviews were performed in external tools (Terrascan), including positioning adjustments to overlapping line data. Elevations referenced to NAVD88 datum were reduced with the application with VDatum v3.6.1. and GEOID12b. Data was exported to LAS format 1.4 for delivery. LAS data has a basic classification produced during the refraction correction process: Emerged and topographic points (1), Noise (7), Submerged Underwater points (40), Derived water surface (42). However, other than this necessary processing classification, the dataset has not been further classified or edited.
• 2018-02-01 00:00:00 - The delivered LAS files were reviewed and processed to classify the point cloud and compute vertical accuracy. A variety of LAStools executables were used to tile the swaths, classify points (noise, ground, and bathymetric points), generate gridded products, and perform the final quantitative accuracy assessment. Global Mapper was used to perform qualitative assessments of the point clouds and gridded products at each step of the classification process. Ecognition was used to generate a water mask for extracting bathymetric points and identifying water surface and other non-bottom bathymetric points. ArcGIS Pro was used to organize and visualize all delivered products and generate web services for team reviews. The final classification includes class 1 (unclassified), class 2 (bare ground), class 7 (low noise), and class 40 (bathymetric point). Class 40 represents seafloor points. Class 1 on land includes all non-ground points (e.g., vegetation, buildings, powerlines). Class 1 in the water includes all non-bathymetric points (e.g., water surface, water column, floating submerged aquatic vegetation, and docks/piers).
• 2018-05-09 00:00:00 - The NOAA Office for Coastal Management (OCM) received 287 las files. The files contained topobathy elevation and intensity measurements in Blue Hill Bay along the coastline of Maine. The data were set to NAD83 2011 UTM Zone 19 North in meters and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 -Unclassified, 2 - Ground, 7 - Low Noise, 40 - Bathymetry. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7, 40. OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. The LAStools software scripts lasinfo and lasvalidate were run on the las 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. Internal OCM scripts were run on the las files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid 12B model, to convert from NAD83 2011 UTM Zone 19 North in meters to geographic coordinates, 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 custom and bulk downloads.