2024 Great Bay NERR UAS Lidar: New Hampshire Salt Marshes

Dates of collection for the Odiorne dataset

Create custom data files by choosing data area, product type, map projection, file format, datum, etc. A new metadata will be produced to reflect your request using this record as a base. Change to an orthometric vertical datum is one of the many options.

Bulk download of data files in LAZ format, geographic coordinates, orthometric heights. Note that the vertical datum (hence elevations) of the files here are different than described in this document. They will be in an orthometric datum.

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 custom download, from the Data Access Viewer (DAV), the raster Digital Elevation Model (DEM) data that were created from this lidar data set.

Entwine Point Tile (EPT) is a simple and flexible octree-based storage format for point cloud data. The data is organized in such a way that the data can be reasonably streamed over the internet, pulling only the points you need. EPT files can be queried to return a subset of the points that give you a representation of the area. As you zoom further in, you are requesting higher and higher densities. A dataset in EPT will contain a lot of files, however, the ept.json file describes all the rest. The EPT file can be used in Potree and QGIS to view the point cloud.

Link to view the point cloud (using the Entwine Point Tile (EPT) format) in the 3D Potree viewer.

This kmz shows the lidar coverage for the 2024 UAS lidar acquisition of New Hampshire salt marshes.

Lidar was captured over a two-day period (05/21-05/22/2024) using a Riegl VUX-1 UAV sensor at an Above Ground Level (AGL) altitude of 115 m, and with a minimum 50% sidelap. On each day, data acquisition occurred within plus or minus 1 hour of predicted low tides. Ground control was provided using a total of ten (10) Propeller Aeropoints distributed evenly across the site each day. Each Aeropoint had a minimum occupation time of 2 hours, and GCPs and checkpoints acquired have a RMSEz of 1.22 cm. For each day, 5 points were used as ground control points (GCPs) and 5 were withheld in processing for independent accuracy checkpoints.

Inertial processing was performed in NovAtel Inertial Explorer Xpress v9.0. Point cloud creation was conducted in Phoenix Lidar SpatialExplorer v7.0.1. The lidar was then processed through the Terrasolid Spatix v.024.002 software modules TerraScan and TerraMatch UAV for alignment, strip adjustment, and .laz output. Blue Marble GlobalMapper v23.1 was used to classify the .laz into the requested classes using automated and manual workflows.

These data were classified as follows:

Class 1 = Unclassified

Class 2 = Ground

Class 7 = Low Noise

Finally a 1-ft Digital Elevation Model (DEM) was created in Blue Marble GlobalMapper v23.1 using a minimum value binning (bin size = 6) grid method, and output as a 32-bit floating-point GeoTIFF formatted raster. No breaklines or hydroflattening processes were developed or applied to the DEM.

The NOAA Office for Coastal Management (OCM) received the UAS lidar data from the Great Bay NERR. The data were in New Hampshire State Plane NAD83(2011), US survey feet coordinates and in NAVD88 (Geoid18) elevations in feet. The data were classified as: 1 - Unclassified, 2 - Ground, 7 - Low Noise. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7.

OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:

1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges.

2. Internal OCM scripts were run on the laz files to:

a. Convert the files from NH State Plane NAD83(2011), US survey feet coordinates to geographic coordinates

b. Convert the files from NAVD88 (Geoid18) elevations to ellipsoid (NAD83 2011) elevations

c. Convert the files from elevations in feet to meters

d. Assign the geokeys, to sort the data by gps time and zip the data to database and to AWS S3