2025 USGS Lidar DEM: Manatee County, FL

Original Product: These are Digital Elevation Model (DEM) data for FL Manatee B25 as part of the required deliverables for the FL Manatee B25 Lidar project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 2.5 feet hydro-flattened Raster DEM.

Original Geographic Extent: FL Manatee B25 covering approximately 875 square miles.

Original Dataset Description: FL Manatee B25 Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.224 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 2025 rev. A. The data was developed based on a horizontal datum/projection of NAD83 (2011), State Plane Florida West (FIPS 0902), U.S. Survey Feet and vertical datum of NAVD88 (GEOID18), U.S. Survey Feet. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 1,141 individual 5,000 ft x 5,000 ft tiles and as tiled bare earth DEMs; all tiled to the same 5,000 ft x 5,000 ft schema.

Ground Conditions: Lidar was collected in early spring 2025, 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 a total of 18 ground control points that were used to calibrate the lidar to known ground locations established throughout the FL Manatee B25 project area. An additional 85 independent accuracy checkpoints, 53 in Bare Earth and Urban landcovers (53 NVA points), 32 in Tall Grass and Brushland/Low Trees categories (32 VVA points), 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 Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 2.5 feet cell size. These raw lidar point cloud data were used to create classified lidar LAS files, 3D breaklines, hydro-flattened DEMs as necessary.

Raster File Type = TIFF

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 2.5 feet

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.

Twenty-Three (23) checkpoints were determined to be photo-identifiable in the intensity imagery and were used to test the horizontal accuracy of the lidar dataset. Using NSSDA methodology (endorsed by the ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014)), horizontal accuracy at the 95% confidence level (called Accuracyr) is computed by the formula RMSEr * 1.7308 or RMSExy * 2.448.

This dataset was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 41 cm RMSEx/RMSEy horizontal accuracy class which equates to a positional horizontal accuracy of plus or minus 1 meter at the 95% confidence level. Using 23 photo-identifiable checkpoints, positional horizontal accuracy of this dataset was found to be RMSEx = 5.6 cm (0.182 ft) and RMSEy = 6.5 cm (0.214 ft), which equates to plus or minus 14.8 cm (0.487 ft) at the 95% confidence level or 8.6 cm (0.281 ft) RMSEr.

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) = 5.41 cm RMSE

Vegetated Vertical Accuracy (VVA) = 13.59 cm at 95th Percentile

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 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.