Data Management Plan (Deprecated)

These data were collected by Leading Edge Geomatics using a Leica Chiroptera II Bathymetric & Topographic Sensor. The data were acquired from October 4, 2016 through November 1, 2016. The data includes topobathy data in LAS 1.2 format classified as created, never classified (0); Unclassified (1); Ground (2); Topo Noise (7); Water (9); Refracted Bathymetric Noise (22); Water Column (25); Bathymetric Bottom or Submerged Topography (26); Water Surface (27); Derived Water Surface (28); Submerged Object (29); Submerged Object International Hydrographic Organization S-57 object, not otherwise specified (30) in accordance with project specifications. The project area covers Marthas Vineyard and Nantucket Islands along with some shoal areas surrounding the islands. The project covers a total of 234 square miles within the AOI. This dataset contains 7030 - 500 m x 500 m lidar tiles.

Original contact information:

Contact Org: National Oceanic and Atmospheric Administration (NOAA), National Ocean Service (NOS), National Geodetic Survey (NGS), Remote Sensing Division

Title: Chief, Remote Sensing Division

Phone: 240-533-9576

Process Steps:

• 2017-01-01 00:00:00 - Data for Marthas Vineyard and Nantucket Islands project was acquired by Leading Edge Geomatics using a Leica Chiroptera II Bathymetric and Topographic lidar sensor. All delivered lidar data is referenced to: Horizontal Datum-NAD83 (2011) epoch: 2010 Projection-UTM Zone 19 North Horizontal Units-meters Vertical Datum-NAVD88, GEOID12B Vertical Units-meters This dataset encompasses 7,030 500m x 500m tiles. Both green lidar data and NIR lidar data was acquired. Leading Edge Geomatics acquired, calibrated and performed the refraction correction to the lidar data. Dewberry received the calibrated green and NIR data and verified complete coverage. Relative accuracy of the green swaths compared to overlapping and adjacent green swaths as well as the relative accuracy of green swaths compared to overlapping and adjacent NIR swaths was verified through the use of Delta-Z (DZ) orthos created in GeoCue software. Intraswath or within a swath relative accuracy was verified using Quick Terrain Modeler. Profiles of elevated planar features, such as roofs, were used to verify horizontal alignment between overlapping swaths. Dewberry then verified absolute vertical accuracy of the swath data prior to full-scale production. Dewberry used ArcGIS to create 2-D breaklines. The bathymetric points exported by the Leica processing software were aggregated into polygons. These 2D breaklines representing the bathy areas were manually reviewed and adjusted where necessary to ensure all well-defined hydrographic features (at 1:1200-scale) were captured with breaklines. Dewberry used algoritms in TerraScan to create the intial ground/submerged topography surface. Dewberry used the 2-D breaklines to classify the bathymetric bottom and ground points properly in TerraScan. All lidar data was peer-reviewed. Dewberry's QAQC also included creating void polygons for use during review. All necessary edits were applied to the dataset. GeoCue software was used to update LAS header information, including all projection and coordinate reference system information. The final lidar data are in LAS format 1.2 and point data record format 3. The final classificaton scheme is as follows: 1-Unclassified 2-Ground 7-Topo Noise 9-Water 22-Refracted Bathymetric Noise 25-Water Column 26-Bathymetric Bottom or Submerged Topography 27-Water Surface 28-Derived Water Surface 29-Submerged Object 30-International Hydrograpic Organization (IHO) S-57 objects All data is then verified by an Independent QC department within Dewberry. The independent QC is performed by separate analysts who do not perform manual classification or editing. The independent QC involves quantitative and qualitative reviews.
• 2017-11-01 00:00:00 - Lidar data classified as ground (2) and submerged topography (26) were then converted to ESRI multipoint format. These multipoints were then used to generate a terrain and the terrain was converted to a raster in IMG format with 1 meter pixel resolution. The terrain and output raster were created over the full project area to reduce edge-matching issues and improve seamlessness. The raster was clipped to the tile grid and named according to project specifications to result in tiled topobathymetric DEMs. All tiled DEMs incorporate the use of the void polygons. The void polygons represent bathymetric areas with no bathymetric bottom returns and are set as NoData in the DEMs. Void polygon creation is described in the final project report and the void polygon metadata.

The vertical accuracy of the final topobathymetric DEMs was tested by Dewberry with 48 independent checkpoints. The same checkpoints that were used to test the source lidar data were used to validate the vertical accuracy of the final DEM products. The survey checkpoints are evenly distributed throughout the project area and are located in areas of non-vegetated terrain, including bare earth, open terrain, and urban terrain (26), vegetated terrain, including forest, brush, tall weeds, crops, and high grass (11), and submerged bottom areas (11).

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8461;