2023 USGS Lidar DEM: Maryland Central

Original Product: These are Digital Elevation Model (DEM) data as part of the required deliverables for the lidar project. Class 2 (Ground) lidar points in conjunction with the hydro breaklines were used to create a 1 ft hydro-flattened Raster DEM.

Full Dataset Geographic Extent:

MD_Central_Processing_1 (Work Unit 300731): Calvert County Maryland, covering approximately 347 square miles.

MD_Central_Processing_2 (Work Unit 300732): Anne Arundel County Maryland, covering approximately 459 square miles.

MD_Central_Processing_3 (Work Unit 300733): Montgomery and Prince George's County Maryland, covering approximately 1073 square miles.

Dataset Description: The 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 meters. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification v2023, Rev. A. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to individual 4000 ft x 6000 ft tiles clipped to the DPA, as tiled Intensity Images and as tiled bare-earth DEMs; all tiled to the same 4000 ft x 6000 ft schema.

Ground Conditions: Lidar was collected in March and December of 2023, 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, Sanborn Map Company, Inc. established independent accuracy check points, in Bare Earth and Urban landcovers, in Tall Grass and Brushland/Low Trees categories. These were used to assess the vertical accuracy of 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 high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 ft cell size.

These lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Raster File Type = TIFF

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 1 foot

Interpolation or Resampling Technique = Bilinear Interpolation

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.

MD_Central_Processing_1 (Work Unit 300731): Calvert County Maryland, covering approximately 347 square miles.

MD_Central_Processing_2 (Work Unit 300732): Anne Arundel County Maryland, covering approximately 459 square miles.

MD_Central_Processing_3 (Work Unit 300733): Montgomery and Prince George's County Maryland, covering approximately 1073 square miles.

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) = 5.44 cm RMSE

Vegetated Vertical Accuracy (VVA) = 12.69 cm at the 95th Percentile

Refer to the USGS Project Report. A link to this report is provided in the URL section of this metadata record.

Datasets contain complete coverage of tiles. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. There are no void areas or missing data. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the DPA 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.