2018 USGS Lidar DEM: Hiawatha National Forest, MI

Original Product: These are Digital Elevation Model (DEM) data for Michigan as part of the required deliverables for the Hiawatha National Forest, Michigan 2018 LiDAR (Albers) project. Class 2 (ground) LiDAR points in conjunction with the hydro breaklines were used to create a 1 meter hydro-flattened Raster DEM.

Full Dataset Geographic Extent: 5 counties in Michigan, covering approximately 795 total square miles, including 10 square miles covered by the QL1 AOI.

Original Dataset Description: The Hiawatha National Forest, Michigan 2018 LiDAR (Albers) project called for the planning, acquisition, processing, and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.71 meters (for the QL2 area) and 0.175 meters (for the QL1 area). Project specifications are based on the U.S. Geological Survey National Geospatial Program Base LiDAR Specification, Version 1.3. LiDAR data were delivered as processed Classified LAS 1.4 files formatted to 2060 individual 1,000 m x 1,000 m tiles (including 42 QL1 tiles), as tiled intensity imagery, and as tiled bare earth DEMs; all tiled to the same 1,000 m x 1,000 m schema. Continuous breaklines were produced in Esri file geodatabase format.

Original Dataset Collection Ground Conditions: LiDAR was collected in fall 2018 and spring 2019, 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, Quantum Spatial, Inc. utilized a total of 19 ground control points that were used to calibrate the LiDAR to known ground locations established throughout the project area. An additional 90 independent accuracy checkpoints, 50 in Bare Earth and Urban landcovers (50 NVA points), 40 in Tall Weeds categories (40 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 digital elevation model (DEM) data for the 2018 USGS Lidar DEM: Hiawatha National Forest, MI dataset 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 DEMs. The purpose of these LiDAR data was to produce high accuracy 3D hydro-flattened digital elevation models (DEMs) with a 1 meter cell size. These raw LiDAR point cloud data were used to create classified LiDAR LAS files, intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Raster File Type = IMG; Bit Depth/Pixel Type = 32-bit float; Raster Cell Size = 1 meter; Interpolation or Resampling Technique = Triangulated Irregular Network (TIN), Linear Interpolation, Proprietary; Required Vertical Accuracy = 0.196

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

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.

MicroStation Version 8; TerraScan Version 18; TerraModeler Version 18; GeoCue Version 2017.1.14.1; Esri ArcGIS 10.3; Global Mapper 19; Leica Cloud Pro 1.2.4, RiProcess 1.8.5; Windows 10 Operating System \\point_cloud\tilecls\*.las

The project specifications require the accuracy (ACCz) of the derived DEM be calculated and reported in two ways: 1. The required NVA is: 19.6 cm at a 95% confidence level, derived according to NSSDA, i.e., based on RMSE of 10 cm in the "bare earth" and "urban" land cover classes. This is a required accuracy. The NVA was tested with 50 checkpoints located in bare earth and urban (non-vegetated) areas. 2. Vegetated Vertical Accuracy (VVA): VVA shall be reported for "tall weeds" land cover classes. The target VVA is: 29.4 cm at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data, i.e., based on the 95th percentile error in all vegetated land cover classes combined. This is a target accuracy. The VVA was tested with 40 checkpoints located in forested and tall weeds (vegetated) areas. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. AccuracyZ has been tested to meet 19.6 cm or better Non-Vegetated Vertical Accuracy at 95% confidence level using RMSE(z) x 1.9600 as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using National Digital Elevation Program (NDEP)/ASRPS Guidelines.

Tested 0.058 meters NVA at a 95% confidence level (or 2.97 cm RMSE) using 50 independent survey points located in open terrain. The survey check points were distributed throughout the project area. The 50 independent check points were surveyed using GPS techniques. See survey report for additional survey methodologies. Elevations from the unclassified LiDAR surface were measured for the x,y location of each checkpoint. Elevations interpolated from the LiDAR surface were then compared to the elevations values of the surveyed control points. The root mean square error vertical (RMSEz) was computed to be 0.03 meters. AccuracyZ has been tested to meet 19.0 cm NVA at 95-percent confidence level using (RMSEz * 1.9600) as defined by the National Standards for Spatial Data Accuracy (NSSDA); assessed and reported using American Society of Photogrammetry and Remote Sensing (ASPRS) Guidelines.

Tested 0.121 meters VVA was calculated using 40 checkpoints located in vegetation at the 95th percentile, derived according to ASPRS Guidelines, Vertical Accuracy Reporting for LiDAR Data. Tested against the DEM.

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 pass Non-Vegetated Vertical Accuracy specifications.

Data cover the entire area specified for this project.

Data is backed up to tape and to cloud storage.

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.