2024 USGS Lidar DEM: Hamilton County, IN

Product: These are Digital Elevation Model (DEM) data for HamiltonIN2024 as part of the required deliverables for the HamiltonIN2024 Lidar project. Class 2 (ground) lidar points in conjunction with the hydro breaklines were used to create a 2 foot hydro-flattened Raster DEM.

Geographic Extent: HamiltonIN2024 covering approximately 485 square miles.

Dataset Description: HamiltonIN2024 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. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 2024 rev. A. The data was developed based on a horizontal projection/datum of NAD83 (2011), State Plane Zone Indiana East, 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 8,648 individual 1,250 ft x 1,250 ft tiles, as tiled first return DSMs, and as tiled bare earth DEMs; all tiled to the same 1,250 ft x 1,250 ft schema.

Ground Conditions: Lidar was collected in February 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 a total of 19 ground control points that were used to calibrate the lidar to known ground locations established throughout the HamiltonIN2024 project area. An additional 92 independent accuracy checkpoints, 61 in Bare Earth and Urban landcovers (61 NVA points), 31 in Tall Grass and Brushland/Low Trees categories (31 VVA points), were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post process the data. The minimum elevation of the DEM files is 379.70 feet and the maximum elevation is 982.75 feet.

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 2 foot cell size. These raw lidar point cloud data were used to create classified lidar LAS files, intensity images, 3D breaklines, hydro-flattened DEMs as necessary.

Raster File Type = TIFF

Bit Depth/Pixel Type = 32-bit float

Raster Cell Size = 2 foot

Interpolation or Resampling Technique = Triangulated Irregular Network

Required Vertical Accuracy = 19.6 cm NVA

See access and use constraints information on GeoHub.

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.

Only checkpoints photo-identifiable in the intensity imagery can be used to test the horizontal accuracy of the lidar. Photo-identifiable checkpoints in intensity imagery typically include checkpoints located at the ends of paint stripes on concrete or asphalt surfaces or checkpoints located at 90 degree corners of different reflectivity, e.g. a sidewalk corner adjoining a grass surface. The xy coordinates of checkpoints, as defined in the intensity imagery, are compared to surveyed xy coordinates for each photo-identifiable checkpoint. These differences are used to compute the tested horizontal accuracy of the lidar. As not all projects contain photo-identifiable checkpoints, the horizontal accuracy of the lidar cannot always be tested.

Lidar vendors calibrate their lidar systems during installation of the system and then again for every project acquired. Typical calibrations include cross flights that capture features from multiple directions that allow adjustments to be performed so that the captured features are consistent between all swaths and cross flights from all directions. This data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data, Edition 2, Version 1.0 (2023) for a 41 cm RMSEh Horizontal Positional Accuracy Class.

The DEM was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data, Edition 2, Version 1.0 (2023) for a 10-cm RMSEv Vertical Accuracy Class. The Dewberry tested vertical positional accuracy was found to be at 2.3 cm.

USGS Determined DEM Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 2.39 cm RMSE

Vegetated Vertical Accuracy (VVA) = 5.51 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.