2016 USFS Lidar DEM: Colville National Forest, WA

Lidar for this AOI was acquired in forty-one (41) flight missions completed on October 12th, 2016.

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Data report from contractor.

Data received by NOAA OCM from USFS region 6.

Differential GPS unit in aircraft collected positions at 2 Hz. Airborne GPS data was processed using the Inertial Explorer (version 8.60.5025) software. Flights were flown with a minimum of 6 satellites in view (10° above the horizon) and with a PDOP of ≤4 when the laser was online.

For all flights, the GPS data can be classified as good, with GPS residuals of 3cm average or better but none larger than 10cm being recorded.

Data collected by the lidar unit is reviewed for completeness, acceptable density and to make sure all data is captured without errors or corrupted values. In addition, all GPS, aircraft trajectory, mission information, and ground control files are reviewed and logged into a database.

Atlantic used a combination of Waypoint and Leica software products to extract the lidar swath data from the raw flight records. Waypoint Inertial Explorer is used to extract the raw IPAS ABGPS/IMU data, which is further processed in combination with controlled base stations to provide the final Smoothed Best Estimate Trajectory (SBET) for each mission. The SBET’s are combined with the raw laser scan files to export the (*.las) formatted swath point clouds.

The calibrated point cloud data from the laser sensor was merged to produce processed (*.las) file(s) including but not limited to 3D position, intensity, and time-stamp. A filtering methodology was utilized to produce a multi-return surface elevation model dataset with bare-earth conditions. GeoCue, TerraScan, and TerraModeler software was used for the initial batch processing and manual editing of the (*.las) point clouds. Outlined in Table 4 are the classification codes utilized for this project.

Digital elevation model data were received from the U.S. Forest Service by the NOAA Office for Coastal Management in ERDAS Imagine format. Files were in the USFS Region 6 Albers Projection (EPSG:9674) with vertical NAVD88 meters. Files were converted to cloud optimized GeoTiff format for distribution on the Digital Coast Data Access Viewer. No information was provided regarding the interpolation of the classified point cloud into digital elevation models.