Data Management Plan

This metadata record describes the light detection and ranging (lidar) dataset titled 2018 - 2019 State of Maine Lidar: Crown of Maine.

Product: These lidar data are processed classified LAS 1.4 files, formatted to 8,056 individual 1,500 m x 1,500 m tiles; used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary. This lidar data set includes unclassified swath LAS 1.4 files, classified LAS 1.4 files, hydro and bridge breaklines, hydro-flattened digital elevation models (DEMs), and intensity imagery.

Geographic Extent: 4 partial counties in Northern Maine, covering approximately 6,732 total square miles.

Dataset Description: The Crown of Maine 2018 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 0.71 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.2. The data were developed based on a horizontal projection/datum of NAD 1983 (2011), UTM Zone 19, meters and vertical datum of NAVD 1988 (GEOID 12B), meters. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 8,056 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-meter schema. Continuous breaklines were produced in Esri file geodatabase format.

Ground Conditions: LiDAR was collected in spring of 2018 and 2019, 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 150 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 256 independent accuracy checkpoints, 149 in Bare Earth and Urban landcovers (149 NVA points), 107 in Tall Weeds categories (107 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data.

Process Steps:

• 2019-01-01 00:00:00 - LAS Point Classification: The point classification was performed as described below. The bare earth surface was manually reviewed to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface was finalized, it was 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 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 the client(s) through numerous conference calls and pilot study areas. All data were manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper was 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.
• 2021-01-27 00:00:00 - The NOAA Office for Coastal Management (OCM) downloaded this data set from this USGS site: ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/ME_CrownofMaine_2018_A18/ The total number of files downloaded and processed was 8,056 from the available folders, which are Blocks 1 & 2. Additional data will be added when it becomes available, and this metadata record updated at that time. The data were in UTM zone 19, (NAD83 2011) coordinates in meters and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 - Unclassified, 2 - Ground,, 7 - Noise, 9 - Water, 10 - Ignored Ground (Breakline Proximity), 17 - Bridge Decks, and 18 - High Noise. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). OCM performed the following processing on 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 ellipsoid elevations using the Geoid12B model, to convert 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 or custom downloads

Data is backed up to tape and to cloud storage.