2016 NOAA NGS Topobathy Lidar DEM: Marthas Vineyard and Nantucket Island, MA

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

This lidar data are an ancillary product of NOAA's Coastal Mapping Program (CMP), created through a wider Integrated Ocean and Coastal Mapping initiative to increase support for multiple uses of the data. The Martha's Vineyard and Nantucket Islands have been identified as having critical topographic and bathymetric data gaps by NOAA. This lidar data will fill those critical gaps. It is not intended for mapping, charting, or navigation.

Data include all lidar returns. Outliers or false returns (e.g., returns from birds, atmospheric particles, and/or system noise) may be present in the data. An automated ground classification algorithm was used to determine bare earth point classification. It should be noted that not all returns were correctly classified; therefore the user should examine for acceptability.

Data for Marthas Vineyard and Nantucket Islands project was acquired by Leading Edge Geomatics using a Leica Chiroptera II Bathymetric and Topographic lidar sensor.

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

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the National Geodetic Survey, the Office for Coastal Management, or its partners.

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

None

Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

OS Independent

The vertical accuracy is tested by extracting the elevation of the pixel that contains the x/y coordinates of the checkpoint and comparing these DEM elevations to the surveyed elevations.

This DEM dataset was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10 cm RMSEz Vertical Accuracy Class. Actual NVA accuracy was found to be RMSEz = 8.1 cm, equating to +/- 15.8 cm at 95% confidence level.

This dataset contains 7030 - 500 m x 500 m lidar tiles.

Not applicable

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).