2019 USGS Lidar: South New Jersey

This metadata record describes the lidar point cloud data encompassing Southern New Jersey, collected as 2 areas of interest through the USGS projects titled 'NJ South 4-County' and 'NJ South FEMA' by the Sanborn Map Company, Inc. NOAA's Office for Coastal Management retrieved the data from the USGS' rockyftp website and processed it to the Digital Coast.

Product: These lidar data are processed Classified LAS 1.4 files, formatted to 3,094 individual 5000 x 5000 foot tiles; used to create intensity images, 3D breaklines and hydro-flattened DEMs as necessary.

Geographic Extent: Atlantic, Cape May, Cumberland, Salem counties New Jersey, covering approximately 2,561 square miles.

Dataset Description: USGS South NJ Lidar project called for the Planning, Acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.5 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, Version 1.3. The data was developed based on a horizontal projection/datum of NAD83 (2011), State Plane New Jersey, feet and vertical datum of NAVD88 (GEOID12B), feet. The Riegl VQ-1560i sensor was used to collect data for the aerial survey campaign. The sensor is attached to the aircraft’s underside and emits rapid laser pulses that are used to calculate ranges between the aircraft and subsequent terrain below. Lidar data was delivered as processed Classified LAS 1.4 files.

Ground Conditions: Lidar was collected in early 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, Sanborn Map Company, Inc. established a total of 20 ground control points that were used to calibrate the lidar to known ground locations established throughout the project area. An additional 97 independent accuracy check points, 56 in Open Terrain/Bare-Earth and Urban landcovers (56 NVA points), 41 in Grass, Brush and Trees categories (41 VVA points), were used to assess the vertical accuracy of the data. These check points were not used to calibrate or post process the data.

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 Rasters, 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 lidar point cloud data were used to create intensity rasters, 3D breaklines, and hydro-flattened DEMs as necessary.

TASK ORDER: 140G0218F0164 USGS CONTRACT: G16PC00051 CONTRACTOR: Sanborn Map Company, Inc. Lidar data were acquired by Aerial Imaging, Inc.. All follow-on processing was completed by the Sanborn Map Company, Inc..

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" : "Riegl VQ-1560i",

"ldrmaxnr" : "15",

"ldrnps" : "0.5",

"ldrdens" : "4.1",

"ldranps" : "0.5",

"ldradens" : "4.1",

"ldrfltht" : "1700",

"ldrfltsp" : "160",

"ldrscana" : "60",

"ldrscanr" : "232",

"ldrpulsr" : "1000",

"ldrpulsd" : "4",

"ldrpulsw" : "0.36",

"ldrwavel" : "1064",

"ldrmpia" : "2",

"ldrbmdiv" : "0.25",

"ldrswatw" : "1905",

"ldrswato" : "30",

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

},

"ldraccur" : {

"ldrchacc" : "0.5",

"rawnva" : "0.238",

"rawnvan" : "56",

"clsnva" : "0.240",

"clsnvan" : "56",

"clsvva" : "0.249",

"clsvvan" : "41"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS overlap bit.",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, but Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridges"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "20",

"clasitem" : "Ignored Ground"

}

}}

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 or 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.

This data set was produced to meet ASPRS Positional Accuracy Standard for Digital Geospatial Data (2014) for a 10-cm RMSEz Vertical Accuracy Class.

The vendor-reported accuracies, taken from the project reports, are as follows:

For the FEMA portion AOI the NVA of the Point Cloud, using 24 GCPs, RMSEz = 0.182 feet (0.0554 meters).

For the 4-County portion AOI the NVA of the Point Cloud, using 56 GCPs, RMSEz = is 0.122 feet (0.03718 meters).

USGS Determined Vertical Accuracy (4-County portion)

NVA = 7.31 cm at 95% Confidence Level (3.73 cm RMSE)

VVA = 7.58 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 raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Data covers the 4-County area specified for this project.

Data is backed up to tape and to cloud storage.