Data Management Plan

Product: These LiDAR data are 36 classified LAS 1.4 files; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: Merrymeeting Bay, ME in Sagadahoc County, covering approximately 2 square miles.

Data set Description: This data set covers a small area in southern Maine, that was collected at the same time as a much larger data set in eastern Maine, but is provided at 16 points per square meter. There is also a data set for the same area that is provided at 8 points per square meter. See the Related Items section of this metadata record for a link to that data set metadata record. Additionally, the hydro breaklines and the Digital Elevation Model (DEM) data created from these 36 lidar files are also available. See the URL section of this metadata record for a link to the hydro breaklines and the Related Item section for a link to the DEM data metadata record. A link to metadata for the larger data set, 2017 Lidar: Eastern Maine, is also provided in the Related Item section.

The 2017 Eastern Maine LiDAR project called for the planning, acquisition, processing, and derivative products of LiDAR data to be collected at a nominal pulse spacing (NPS) of 0.7 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.2. The data was developed based on a horizontal projection/datum of NAD83 (2011) UTM Zone 19, meters and vertical datum of NAVD88 (GEOID12B), meters.

Ground Conditions: LiDAR was collected in the spring and fall of 2017, while no snow was on the ground and rivers were at or below normal levels. In order to post process the LiDAR data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Quantum Spatial, Inc. established a total of 181 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 301 independent accuracy checkpoints, 178 in Bare Earth and Urban landcovers (178 NVA points), 123 in Forested, Shrubs, and Tall Weeds categories (123 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

Lineage Statement:
Quantum Spatial collected Light Detection and Ranging (LIDAR) data in Maine for the State of Maine. NOAA OCM received the data and ingested it into the Digital Coast Data Access Viewer for distribution.

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 to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface is finalized, it is then used to generate all hydro-breaklines through heads-up digitization. All ground (ASPRS Class 2) LiDAR data inside of the Lake Pond and Double Line Drain hydro-flattened breaklines were then classified to Water (ASPRS Class 9) using TerraScan macro functionality. A buffer of 1 meter was also used around each hydro-flattened feature to classify these ground (ASPRS Class 2) points to Ignored ground (ASPRS Class 10). All Lake Pond Island and Double Line Drain Island features were checked to ensure that the ground (ASPRS Class 2) points were reclassified to the correct classification after the automated classification was completed. ASPRS Class 7 was used for all low nois points while ASPRS Class 18 was used for all high noise points. Bridge decks were classified to ASPRS Class 17. All overlap data was processed through automated functionality provided by TerraScan to classify the overlapping flight line data to approved classes by USGS. The overlap data was classified using standard LAS overlap bit. These classes were created through automated processes only and were not verified for classification accuracy. Due to software limitations within TerraScan, these classes were used to trip the withheld bit within various software packages. These processes were reviewed and accepted by USGS through numerous conference calls and pilot study areas. All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper is used as a final check of the bare earth dataset. GeoCue was then used to create the deliverable industry-standard LAS files for both the All Point Cloud Data and the Bare Earth. Quantum Spatial, Inc. proprietary software was used to perform final statistical analysis of the classes in the LAS files, on a per tile level to verify final classification metrics and full LAS header information.
• 2019-07-19 00:00:00 - The NOAA Office for Coastal Management (OCM) received 36 laz 1.4 format files from the State of Maine GIS. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 19 NAD83(2011) meters coordinates and NAVD88 (Geoid12b) elevations in meters. The lidar classes available are: 1 (Unclassified), 2 (Ground), 7 (Low Noise), 9 (Inland Water), 10 (Ignored Ground), 17 (Bridge Decks), 18 (High Noise). OCM did the following processing to the data for Digital Coast storage and provisioning purposes: 1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. 2. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to NAD83 (2011) ellipsoid elevations using the Geoid 12b model, to convert from UTM Zone 19 North NAD83 (2011) coordinates 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 bulk and custom downloads.

Data is backed up to tape and to cloud storage.