2018 - 2019 USGS Lidar DEM: Hudson River Region, NY

These are Digital Elevation Model (DEM) data for Columbia, Jefferson, Lewis, Rensselaer, Saratoga, Warren, and Washington counties in New York as part of the required deliverables for the NY Hudson River Region LiDAR project. Class 2 (ground) LiDAR points in conjunction with the hydro breaklines were used to create a 0.5 meter hydro-flattened Raster DEM.

Geographic Extent:

West AOI (Jefferson and Lewis Counties) covering approximately 626 square miles.

East AOI (Columbia, Rensselaer, Saratoga, Warren, and Washington Counties) covering approximately 2,548 square miles.

Dataset Description: This data project was undertaken in 2018 and 2019. The Hudson River Region LiDAR project called for the Planning, Acquisition, processing and derivative products of lidar data to be spaced at 0.8 ppm squared. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3. LiDAR data was delivered as Classified LAS 1.4 files, formatted to individual 500 m x 500 m tiles and as tiled bare earth DEMs; all tiled to the same 500 m x 500 m schema.

Ground Conditions: Lidar was collected in 2018 and 2019 in full leaf out conditions. Because of this, a "produced to meet" statement is not provided for Vegetated Vertical Accuracy (VVA).

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 DEMs. These lidar point cloud data were used to create hydro-flattened DEMs.

Any conclusions drawn from the analysis of this information are not the responsibility of 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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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 Connect Version 10.11; TerraScan Version 19.003; ESRI ArcGIS 10.4.1, Windows 7 Operating System, ESP Analyst, ESP Utilities

L3Harris Horizontal Accuracy Information:

Horiz accuracy = 15.6 cm RMSEr

L3Harris Vertical Accuracy Information:

The project specifications require that Non-Vegetated Vertical Accuracy (NVA) and Vegetated Vertical Accuracy (VVA) be computed for calibrated and classified lidar point cloud files. The required accuracy (ACCz) is: 18.13 cm at a 95% confidence level for NVA, derived according to NSSDA, i.e., based on RMSE (z) of 9.25 cm in the bare earth and urban land cover classes.

The NVA was tested with 1464 checkpoints located in bare earth and urban (non-vegetated) areas. These check points were not used in the calibration or post processing of the lidar point cloud data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. Elevations from the classified lidar surface were measured for the x,y location of each check point. Elevations interpolated from the lidar surface were then compared to the elevation values of the surveyed control points. AccuracyZ has been tested to meet 18.13 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.

This data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10cm RMSEz Vertical Accuracy Class equating to NVA =+/- 19.6cm at 95% confidence level. The lidar point cloud was collected during leaf-out conditions with areas of vegetation considered as obscured, therefore no implied or stated accuracy is provided for VVA.

USGS Determined DEM Vertical Accuracy:

Non-Vegetated Vertical Accuracy (NVA) = 12 cm at 95% Confidence Level or 6.1 cm RMSE

Vegetated Vertical Accuracy (VVA) = 14 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. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Due to a lack of point cloud data, there is no DEM for tile 5990047540.

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.