Data Management Plan

USGS NGTOC task order 140G0219F0262 required Fall 2019 / Spring 2020 leaf-off LiDAR surveys to be collected over 6,245 square miles covering parts of Eastern and Central Mississippi. Aerial LiDAR data for this task order was planned, acquired, processed, and produced at an aggregate nominal pulse spacing (ANPS) of less than or equal to 0.71 meters and in compliance with USGS National Geospatial Program LiDAR Base Specification version 1.3.

This metadata 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 2018 MS NRCS East lidar was ingested into the Data Access Viewer for custom product generation by leveraging USGS hosted Entwine Point Tiles.

Process Steps:

• 2021-01-14 00:00:00 - Aircraft and Sensor Information and Flight Plan Execution Atlantic operated a Cessna Caravan (N167PM) outfitted with an Optech Galaxy Prime LiDAR system during the collection of the project area. Atlantic acquired 65 passes of the AOI as a series of perpendicular and/or adjacent flight-lines executed in 5 flight missions conducted between January 9, 2020 and January 14, 2021. Onboard differential Global Navigation Satellite System (GNSS) unit(s) recorded sample aircraft positions at 2 hertz (Hz) or more frequency. LiDAR data was only acquired when a minimum of six (6) satellites were in view.
• 2020-01-17 00:00:00 - Ground Control Survey A total of 64 ground survey points were collected in support of this project, including 9 LiDAR Control Points (LCP), 32 Non-vegetated Vertical Accuracy (NVA) and 23 Vegetated Vertical Accuracy (VVA). Point cloud data accuracy was tested against a Triangulated Irregular Network (TIN) constructed from LiDAR points in clear/open areas. A clear and open area can be characterized with respect to topographic and ground cover variation such that a minimum of 5 times the Nominal Pulse Spacing (NPS) exists with less than 1/3 of the RMSEZ deviation from a low-slope plane. Slopes exceeding 10 percent were avoided. Each land cover type representing 10 percent or more of the total project area was tested and reported with a VVA. In land cover categories other than dense urban areas, the tested points did not have obstructions 45 degrees above the horizon to ensure a satisfactory TIN surface. The VVA value is provided as a target. It is understood that in areas of dense vegetation, swamps, or extremely difficult terrain this value may be exceeded. The NVA value is a requirement that must be met, regardless of any allowed “busts” in the VVA(s) for individual land cover types within the project. Checkpoints for each assessment (NVA and VVA) are required to be well-distributed throughout the land cover type, for the entire project area.
• 2021-09-23 00:00:00 - LiDAR Point Cloud Generation Atlantic used Optech software products to download the IPAS ABGNSS/IMU data and raw laser scan files from the airborne system. Applanix Pospac 8.5 is used to extract the raw IPAS ABGNSS/IMU data, which is further processed in combination with controlled base stations to provide the final Smoothed Best Estimate Trajectory (SBET) for each mission. The SBETs are combined with the raw laser scan files to export the LiDAR ASCII Standard (*.las) formatted swath point clouds. Departures from planarity of first returns within single swaths in non-vegetated areas were assessed at multiple locations with hard surface areas (parking lots or large rooftops) inside the project area. Each area was evaluated using signed difference rasters (maximum elevation – minimum elevation) at a cell size equal to 2 x ANPS, rounded to the next integer.
• 2021-09-23 00:00:00 - LiDAR Calibration Using a combination of GeoCue, TerraScan and TerraMatch; overlapping swath point clouds are corrected for any orientation or linear deviations to obtain the best fit swath-to-swath calibration. Relative calibration was evaluated using advanced plane-matching analysis and parameter corrections derived. This process was repeated interactively until residual errors between overlapping swaths, across all project missions, was reduced to ≤2cm. A final analysis of the calibrated lidar is preformed using a TerraMatch tie line report for an overall statistical model of the project area. Individual control point assessments for this project can be found in Section VI of this report. Upon completion of the data calibration, a complete set of elevation difference intensity rasters (dZ Orthos) are produced. A user-defined color ramp is applied depicting the offsets between overlapping swaths based on project specifications. The dZ orthos provide an opportunity to review the data calibration in a qualitative manner. Atlantic assigns green to all offset values that fall below the required RMSDz requirement of the project. A yellow color is assigned for offsets that fall between the RMSDz value and 1.5x of that value. Finally, red values are assigned to all values that fall beyond 1.5x of the RMSDz requirements of the project.
• 2021-09-23 00:00:00 - LiDAR Classification Multiple automated filtering routines are applied to the calibrated LiDAR point cloud identifying and extracting bare-earth and above ground features. GeoCue, TerraScan, and TerraModeler software was used for the initial batch processing, visual inspection and any manual editing of the LiDAR point clouds. Atlantic utilized collected breakline data to preform classification for class 9 (Water).
• 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). Vertically, no changes were made to the vertical datum (NAVD88 GEOID12B; EPSG 5703).
• 2022-06-07 00:00:00 - The NOAA Office for Coastal Management (OCM) created references to the Entwine Point Tiles (EPT) 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/MS_NRCS_East_1_2018/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/MS_NRCS_East_2_2018/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/MS_NRCS_East_3_2018/ept.json https://s3-us-west-2.amazonaws.com/usgs-lidar-public/MS_NRCS_East_4_2018/ept.json

Data is available online for bulk and custom downloads.

Data is backed up to tape and to cloud storage.