2018 - 2019 USGS Lidar: Hudson River Region, NY

These lidar data were processed as classified LAS 1.4 files, formatted to individual 500 m x 500 m tiles; used to create breaklines and hydro-flattened DEMs.

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. This project called for the flight planning, collection, and processing of point cloud products. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3. These data were created based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator, meters and vertical datum of NAVD88 (GEOID12B), meters. These LiDAR data were delivered as processed classified LAS 1.4 files compressed to LAZ files.

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 Entwine Point Tiles (EPT) 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.

USGS Contract No. 140G0120C0007 CONTRACTOR: L3Harris. SUBCONTRACTOR: ESP Associates Inc. These LiDAR data were acquired and calibrated by L3Harris. Point cloud classificatoin was completed by the subcontractor.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "U.S. Geological Survey (USGS) - National Geospatial Program (NGP) Lidar Base Specification v1.3",

"ldrsens" : "IntelliEarth GmAPD LiDAR",

"ldrmaxnr" : "1",

"ldrnps" : "0.35",

"ldrdens" : "8",

"ldranps" : "8",

"ldradens" : "8",

"ldrfltht" : "4289",

"ldrfltsp" : "220",

"ldrscana" : "15",

"ldrscanr" : "16",

"ldrpulsr" : "50",

"ldrpulsd" : "0.5",

"ldrpulsw" : "(4.5696e-3*altitude)",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "4.57",

"ldrswatw" : "2298",

"ldrswato" : "55",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B",

"ldrcrs" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "0.30",

"rawnva" : "0.142",

"rawnvan" : "1634",

"clsnva" : "0.142",

"clsnvan" : "1634"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld (ignore) points were identified in these files using the standard LAS Withheld bit.",

"lasolap" : "Standard LAS overlap bit not used due to 55 percent overlap project design",

"lasintr" : "5",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Noise, Low"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Decks"

}

}}

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 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

These LAS data files include all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. No void areas or missing data exist. The point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

All data covers the project area, tile to tile with no gaps or no data areas exceeding specifications

Data is backed up to tape and to cloud storage.

The NOAA Office for Coastal Management (OCM) ingested references to the USGS Entwine Point Tile (EPT) files hosted on Amazon Web Services (AWS) into the Digital Coast Data Access Viewer (DAV). The DAV accesses the point cloud as it resides on AWS under the usgs-lidar-public-container.