Data Management Plan

Dataset Description: The Matanuska - Susitna Borough 3DEP LiDAR project called for the planning, acquisition, and processing of LiDAR data collected at an aggregate nominal pulse spacing (ANPS) of 0.71 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.3. The data was developed based on the NAD83 horizontal datum and NAVD88 (GEOID12B) vertical datum. Data was projected in Alaska State Plane Zone 4. All units are in US Survey Feet. LiDAR data was delivered as processed Classified LAS 1.4 files, formatted to 4236 individual 3,000 ft x 3,000 ft tiles.

Product: Classified LAS 1.4 files formatted to 4236 3,000 ft x 3,000 ft tiles for the Matanuska - Susitna 3DEP Project Area.

Delivery 1/B1: (Work Unit 180695) - 3745 tiles

Delivery 2/B2: (Work Unit 213376) - 491 tiles

Geographic Extent: This dataset and derived products encompass an area covering approximately 1099 square miles in south west Alaska.

Delivery 1/B1: (Work Unit 180695) - 951 square miles

Delivery 2/B2: (Work Unit 213376) - 148 square miles

Derived products include: tiled Intensity Imagery, tiled DZ orthos, tiled bare earth DEMs and shaded relief rasters, tiled Highest Hit Digital Surface Models and shaded relief rasters, tiled 1 ft contour shapefiles, 2D building footprints, and 3D waters edge breaklines.

Ground Conditions:

Delivery 1/B1: (Work Unit 180695)

LiDAR was collected in summer 2019, while the presence of snow on the ground was at a minimum 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, McClintock and Associates established a total of 57 ground control points distributed throughout the Matanuska - Susitna Borough 3DEP, Alaska project area. LiDAR data was calibrated to these known ground locations. An additional 93 independent accuracy checkpoints, 52 in Bare Earth and Urban landcovers (NVA points) and 41 in Tall Grass, Tundra and Shrub categories (VVA points), were used to assess the vertical accuracy of the project data. These checkpoints were not used to calibrate or post process the data.

Delivery 2/B2: (Work Unit 213376)

Lidar was collected in summers of 2019 and 2020, while the presence of snow on the ground was at a minimum 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, McClintock Land Associates established a total of 13 ground control points distributed throughout the Matanuska - Susitna Borough 3DEP, Alaska project area. Lidar data was calibrated to these known ground locations. An additional 34 independent accuracy checkpoints, 25 in Bare Earth and Urban landcovers (NVA points) and 9 in Tall Grass, Forest and Shrub categories (VVA points), were used to assess the vertical accuracy of the project data. These checkpoints were not used to calibrate or post process the data.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the Entwine Point Tiles (EPT) hosted by USGS on Amazon Web Services.

Lineage Statement:
The NOAA Office for Coastal Management (OCM) ingested references to the USGS Entwine Point Tile (EPT) files hosted on Amazon Web Services (AWS) into the Digital Coast Data Access Viewer (DAV). The DAV accesses the point cloud as it resides on AWS under the usgs-lidar-public-container.

Process Steps:

• 2020-01-08 00:00:00 - LiDAR Pre-Processing: 1. Review flight lines and data to ensure complete coverage of the study area and positional accuracy of the laser points. 2. Resolve kinematic corrections for aircraft position data using kinematic aircraft GPS and static ground GPS data. 3. Develop a smoothed best estimate of trajectory (SBET) file that blends post-processed aircraft position with sensor head position and attitude recorded throughout the survey. 4. Calculate laser point position by associating SBET position to each laser point return time, scan angle, intensity, etc. Create raw laser point cloud data for the entire survey in *.las format. Convert data to orthometric elevations by applying a geoid correction. 5. Import raw laser points into manageable blocks to perform manual relative accuracy calibration and filter erroneous points. Classify ground points for individual flight lines. 6. Using ground classified points per each flight line, test the relative accuracy. Perform automated line-to-line calibrations for system attitude parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calculate calibrations on ground classified points from paired flight lines and apply results to all points in a flight line. Use every flight line for relative accuracy calibration. 7. Adjust the point cloud by comparing ground classified points to supplemental ground control points. 8. Single swath nominal pulse spacing (NPS) was designed to be 0.50 meters at nadir. Aggregate Nominal Pulse Spacing (ANPS) was calculated to be 3.76 meters for the pilot dataset using all valid first return points.
• 2020-01-08 00:00:00 - LiDAR Post-Processing: 1. Classify data to ground and other client designated classifications using proprietary classification algorithms. 2. Manually QC data classification 3. After completion of classification and final QC approval, calculate final NVA for the project using ground control quality check points.
• Original point clouds in LAS/LAZ format were restructured as Entwine Point Tiles and stored on Amazon Web Services. The data were re-projected horizontally to WGS84 web mercator (EPSG 3857) and the vertical units were converted to meters (NAVD88 Geoid12B).
• 2023-06-21 00:00:00 - The NOAA Office for Coastal Management (OCM) created references to the Entwine Point Tile (EPT) files that were ingested into the NOAA Digital Coast Data Access Viewer (DAV). No changes were made to the data. The DAV will access the point cloud as it resides on Amazon Web Services (AWS) under the usgs-lidar-public container. These are the AWS URLs being accessed: https://s3-us-west-2.amazonaws.com/usgs-lidar-public/AK_MatSuBorough_B1_2019/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/AK_MatSuBorough_B2_2019/ept.json

Data is available online for bulk and custom downloads.

Data is backed up to tape and to cloud storage.