2019 USGS Lidar DEM: South New Jersey (4 County)

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Bulk download of data files in GeoTIFF format, NJ State Plane NAD83(2011), U.S. feet coordinates and elevations in NAVD88(Geoid12B) feet.

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

Link to the USGS Project Report that provides information about the project, vertical accuracy results, and the point classes and sensors used.

This link is to the reports, breaklines, metadata, spatial metadata, and shapefiles.

Link to the lidar report

The following steps describe the Raw Data Processing and Calibration process: 1) Technicians processed the raw data to LAS format flight lines using the ABGNSS/IMU solution. 2) Technicians use TerraSolid TerraMatch to calculate initial calibration adjustment angles by mission and/or block. This is accomplished by identifying ground and above ground feature observations between flight-lines and calculating the offsets. The technician then analyzed the results and made any necessary additional adjustment until it is acceptable. 3) Once the angle calculation was completed the adjusted settings were applied to all of the flight-lines of the mission and/or block and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight-line overlaps match and adjusted as necessary until the results met the project specifications. 4) The technicians checked and corrected the vertical misalignment of all flight-lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 6 cm RMSEz within individual swaths and less than or equal to 8 cm RMSDz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the calibrated point cloud against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met. Point classification was performed according to USGS Lidar Base Specification v1.3, and breaklines were collected for water features. Bare earth DEMs were exported from the classified point cloud using collected breaklines for hydroflattening.

LAS Point Classification: The point classification is performed as described below. The bare-earth surface is manually reviewed to ensure correct classification on the Class 2 (Ground) points. After the bare-earth surface is edited and QC'd, it is then used to generate all hydro-breaklines through heads-up digitization. All ground (ASPRS Class 2) lidar data inside of the Lake Pond and River Pond hydro flattening breaklines were then classified to water (ASPRS Class 9) using LP360 functionality. A buffer of 2 feet was also used around each hydro-flattened feature to classify these ground (ASPRS Class 2) points to Ignored ground (ASPRS Class 20). All Lake Pond Island and River Stream Island features were checked to ensure that the ground (ASPRS Class 2) points were reclassified to the correct classification after the automated classification was completed. All overlap data was processed through automated functionality provided by TerraScan to classify the overlapping flight-line data to approved classes by USGS. The overlap data was classified using standard LAS overlap bit. These classes were created through automated processes only and were not verified for classification accuracy. All data was manually reviewed and any remaining artifacts removed using functionality provided by TerraScan and TerraModeler. Global Mapper is used as a final check of the bare-earth dataset. GeoCue was then used to create the deliverable industry-standard LAS files for the Classified Point Cloud Data. LAStools, LP360 and TerraScan software was used to perform statistical analysis of the classes in the LAS files, on a per tile level to verify classification metrics and full LAS header information.

Hydro-Flattened Bare Earth DEM Process: Class 2 (ground) and hydro-flattened breaklines were used to create a 2 foot Raster DEM. Using automated scripting routines within LP360, a IMG file was created for each tile. Each terrain is reviewed using Global Mapper to check for any surface anomalies or incorrect elevations found within the surface.

The NOAA Office for Coastal Management (OCM) created references to the USGS GeoTIFF files that were ingested into the NOAA Digital Coast Data Access Viewer (DAV). No changes were made to the data. The DAV will access the raster data as it resides on Amazon Web Services (AWS).

These are the GeoTIFF files that are being accessed:

https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/OPR/Projects/NJ_South_Jersey_Lidar_2018_B18/NJ_SouthernNJ_2018/TIFF/