Data Management Plan

Product: These are Digital Elevation Model (DEM) data for Franklin, Oxford, Piscataquis, and Somerset Counties, Maine as part of the required deliverables for the 2016 Maine Lidar project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened raster DEM.

Geographic Extent: Four partial counties in western Maine, covering approximately 5,034 total square miles

Dataset Description: Maine 2016 QL2 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 NAVD1988 (Geoid 12B), meters. Lidar data was delivered as flightline-extent unclassified LAS swaths, as processed Classified LAS 1.4 files formatted to 6,115 individual 1,500 meter x 1,500 meter tiles, as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 1,500 meter x 1,500 schema. Continuous breaklines were produced in Esri file geodatabase format. Continuous contours with an interval of 1 foot were created in Esri file geodatabase format.

Ground Conditions: Lidar was collected in spring of 2016, 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. utilized a total of 101 ground control points that were used to calibrate the lidar to known ground locations established throughout the Maine project area. An additional 205 independent accuracy checkpoints, 118 in Bare Earth and Urban landcovers (118 NVA points), 87 in Forested, Brushland/Trees, and Tall Weeds/Crops categories (87 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. In addition to the bare earth DEMs, the topobathy lidar point data are also available. These data are available for custom download here: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6264 Breaklines created from the lidar area also available for download in either gdb or gpkg format at: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/6264/breaklines. The DEM and breakline products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA, OCM or its partners.

Process Steps:

• 2016-01-01 00:00:00 - Raw Data and Boresight Processing: The boresight for each lift was done individually as the solution may change slightly from lift to lift. The following steps describe the Raw Data Processing and Boresight process: 1) Technicians processed the raw data to LAS format flight lines using the final GPS/IMU solution. This LAS data set was used as source data for boresight. 2) Technicians first used Quantum Spatial, Inc. proprietary and commercial software to calculate initial boresight adjustment angles based on sample areas selected in the lift. These areas cover calibration flight lines collected in the lift, cross tie and production flight lines. These areas are well distributed in the lift coverage and cover multiple terrain types that are necessary for boresight angle calculation. The technician then analyzed the results and made any necessary additional adjustment until it is acceptable for the selected areas. 3) Once the boresight angle calculation was completed for the selected areas, the adjusted settings were applied to all of the flight lines of the lift and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight line overlaps match for the entire lift and adjusted as necessary until the results met the project specifications. 4) Once all lifts were completed with individual boresight adjustment, the technicians checked and corrected the vertical misalignment of all flight lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 7 cm RMSEz within individual swaths and less than or equal to 10 cm RMSEz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the boresighted flight lines against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met.
• 2016-01-01 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. All bridge decks were classified to 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 us 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.
• 2016-01-01 00:00:00 - Hydro Flattened Raster DEM Process: Class 2 (Ground) lidar points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened raster DEM. Using automated scripting routines within ArcMap, an ERDAS Imagine .IMG file was created for each tile. Each surface is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.
• 2017-05-16 00:00:00 - The NOAA Office for Coastal Management (OCM) received the data in img format. The bare earth raster files were at a 1 m grid spacing. The data were in UTM Zone 19 coordinates and NAVD88 elevations in meters. OCM copied the raster files to database and https for Digital Coast storage and provisioning purposes.
• 2024-07-23 00:00:00 - Data were converted from Imagine format to Cloud Optimized GeoTiff format to better support online access. Vertical georeferencing was also added.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=6267;