Data Management Plan

The NOAA Chesapeake Bay MD1804 Option 1 West 4 Topobathymetric lidar data were collected by NV5 Geospatial, Inc. (NV5) using a Riegl VQ-880-GH system. The Chesapeake Bay MD1804 Option 1 West 4 acquisition spanned from 20190312-20190419 in 9 missions. The Chesapeake Bay MD1804 Option 1 West 4 dataset includes Topobathymetric data in LAS format 1.4, point data record format 6, with the following classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards:

1 - unclassified

2 - ground

7 - noise

40 - bathymetric bottom or submerged topography

43 - submerged object

45 - water column

1 Overlap - edge clip

This data set also includes lidar intensity values, number of returns, return number, time, and scan angle. The 100 meter buffered NOAA Chesapeake Bay MD1804 Option 1 West 4 project area covers approximately 492.737 square kilometers of an area encompassing a portion of the Chesapeake Bay and the nearby census designated places of Solomons, California, Hollywood, Lusby, Broomes Island, and St Leonard, Maryland. LAS files were compiled in 500 m x 500 m tiles. The NOAA Chesapeake Bay MD1804 Option 1 West 4 dataset is comprised of 2,593 - 500 m x 500 m LAS tiles.

Process Steps:

• 2020-11-19 00:00:00 - Data for the NOAA Chesapeake Bay MD1804 Option 1 West 4 Topobathymetric lidar project area was acquired by NV5 Geospatial (NV5) using a Riegl VQ-880-GH Topobathymetric lidar system. All derived LAS data is referenced to: Horizontal Datum-NAD83(2011) epoch: 2010.00 Projection-UTM Zone 18N Horizontal Units-meters Vertical Datum-GRS80 Ellipsoid Vertical Units-meters The NOAA Chesapeake Bay MD1804 Option 1 West 4 dataset encompasses 2,593 - 500m x 500m tiles in an area encompassing a portion of the Chesapeake Bay and the nearby census designated places of Solomons, California, Hollywood, Lusby, Broomes Island, and St Leonard, Maryland. Lidar data were acquired with a VQ-880-GH Riegl sensor. The collected lidar data were immediately processed in the field by NV5 to a level that will allow QA\QC measures to determine if the sensor is functioning properly and assess the coverage of submerged topography. An initial SBET was created in POSPAC MMS 8.3 SP3 and loaded into RiProcess which applies pre-calibrated angular misalignment corrections of scanner position to extract the raw point cloud into geo-referenced LAS files. These files were inspected for sensor malfunctions and then passed through automated raster generation using LAStools to develop an initial assessment of bathymetric coverage. NV5 reviewed all acquired flight lines to ensure complete coverage and positional accuracy of the laser points. These rasters were also used to create an initial product in Quick Look Coverage Maps. These Quick Look files are not fully processed data or final products but provide rapid assessment of approximate coverage and depth penetration. NV5 resolved kinematic corrections for aircraft position data using aircraft GNSS and Applanix's proprietary PP-RTX solution. When PP-RTX was not used, NV5 conducted static Global Navigation Satellite System (GNSS) ground surveys (1 Hz recording frequency) using base stations over known monument locations during flights. After the airborne survey, static GPS data were triangulated with nearby Continuously Operating Reference Stations (CORS) using the Online Positioning User Service (OPUS) for precise positioning. Multiple independent sessions over the same base station were performed to confirm antenna height measurements and to refine position accuracy. This data was used to correct the continuous on board measurements of the aircraft position recorded throughout the flight. A final smoothed best estimate trajectory (SBET) was developed that blends post-processed aircraft position with attitude data. Using the SBETs, sensor head position and attitude were then calculated throughout the survey. Trimble Business Center v.3.90, Blue Marble Geographic Calculator 2019, and PosPac MMS 8.3 SP3 were used for these processes.
• 2020-11-19 00:00:00 - Following final SBET creation, NV5 used RiProcess 1.8.5 to calculate laser point positioning by associating SBET positions to each laser point return time, scan angle, and intensity. Terra 19 and LasTools were used to classify water surface and create a water surface model. They are created for single swaths to ensure temporal differences and wave or water surface height variations between flight lines do not impact the refraction of the bathymetric data. These models are used in NV5's LasMonkey refraction tool to determine the accurate positioning of bathymetric points. All lidar data below water surface models were classified as water column to be refracted. Light travels at different speeds in air versus water and its direction of travel or angle is changed or refracted when entering the water column. The refraction tool corrects for this difference by adjusting the depth (distance traveled) and horizontal positioning (change of angle/direction) of the lidar data. Using raster-based QC methods, the output data is verified to ensure the refraction tool functioned properly. Once all data was refracted by flight line data was exported to LAS 1.4 format and combined into 500 m x 500 m tiles. Data were then further calibrated using TerraMatch. NV5 used custom algorithms in TerraScan to classify the initial ground/submerged topography surface points. Relative accuracy of overlapping swaths was compared and verified through the use Delta-Z (DZ) orthos created using NV5's Las Product Creator. Absolute vertical accuracy of the calibrated data was assessed using ground survey data and complete coverage was again verified. Post automated classification: NV5 then performed manual editing to review all classification and improve the final Topobathymetric surface. NV5's LasMonkey was used to update LAS header information, including all projection and coordinate reference system information. The final lidar data are in LAS format 1.4 and point data record format 6. 1 - unclassified 2 - ground 7 - noise 40 - bathymetric bottom or submerged topography 43 - submerged object 45 - water column 1 Overlap - edge clip
• The NOAA Office for Coastal Management (OCM) received files in las format. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 18 coordinates and ellipsoid elevations in meters. OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. Converted from UTM Zone 18 to geographic coordinates 2. Sorted by gps time 3. Compressed the data using laszip

Data is available online for bulk or custom downloads

Data is backed up to tape and to cloud storage.