2024 USGS Topobathy Lidar DEM: Breton Island, LA

Original Product: These are Digital Elevation Model (DEM) data delivered as part of the Breton Island topobathy lidar project. Class 2 (ground) and class 40 (bathymetry) lidar points were used to create a 1-meter tiled topo-bathy DEM.

Original Geographic Extent: Breton Island and the surrounding waters in the Gulf of Mexico, covering approximately 39 square miles.

Original Dataset Description: The Breton Island Topobathymetric Lidar Project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meter (QL1) in the topographic domain and 0.71 meter (QL2b) in the bathymetric domain. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, version 1.4. The data was developed based on a horizontal projection/datum of NAD83 (2011), UTM zone 16N, meters and vertical datum of NAVD88 (GEOID18), meters. Lidar data were delivered as processed Classified LAS 1.4 files, formatted to 484 individual 500 m x 500 m tiles, as tiled Intensity Imagery, and as tiled topobathymetric DEMs; all tiled to the same 500 m x 500 m schema.

Ground Conditions: Lidar was collected in November and December 2024, 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, Dewberry established 10 ground control points that were used to calibrate the lidar to known ground positions established throughout the project area. An additional 39 independent accuracy checkpoints in bare earth and urban land cover (NVA), and 10 in submerged land cover (BVA)--were used to assess the vertical accuracy of the 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 GeoTIFF files hosted by USGS on Amazon Web Services.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Intensity Images, Breaklines and Raster DEM. The purpose of these lidar data was to produce a high accuracy Digital Elevation Model (DEM) with a 1 meter cell size. These lidar point cloud data were used to create intensity images, breaklines, and DEMs as necessary.

Raster File Type = GeoTIFF

Bit Depth/Pixel Type = 32 bit float

Raster Cell Size = 1 Meter

Interpolation or Resampling Technique = Triangulated Irregular Network

Required Vertical Accuracy = 19.6 cm NVA

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

To the extent possible under law, the U.S. Government has waived all copyright and related or neighboring rights to this dataset.

Data is available online for bulk and custom downloads.

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.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class.

USGS Determined DEM Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 3.02 cm RMSE

Topobathymetric data covers the project boundary to the fullest extent possible depending on water clarity, environmental conditions, and sensor signal returns. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the entire area specified for this project.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS GeoTIFF files that are hosted on Amazon Web Services (AWS), into the Digital Coast Data Access Viewer (DAV). The DAV accesses the raster data as it resides on AWS.