Processing with USGS/Publicly Available DEMs

For systems equipped without LiDAR, USGS has a published site with publicly available DEMs for much of the continental United States. To get started: 

Download DEM

1. Visit USGS LidarExplorer
2. Move to the DEMs tab
3. Enable Show where DEMs exist?
4. Navigate to the location of your survey and draw an AoI around the area
5. Expand the DEMs within AoI dropdown in the right panel
6. Select the highest resolution DEM available (typically 1 meter)
7. In the new tab opened, scroll to the TIFF download link and download the DEM 

To ensure compatibility with field sensor data and GRYFN Processing Tool, the vertical datum must be converted properly. GRYFN recommends using the NASA Ames Stereo Pipeline, with instructions below. 

Converting DEM Vertical Datum

1. For Windows users, install Windows Subsystem for Linux
2. Open Windows terminal
3. From the dropdown menu, select Ubuntu (or other Linux distro)
4. First time users should run the following commands to install NASA Ames Stereo Pipeline

   1. wget https://github.com/NeoGeographyToolkit/StereoPipeline/releases/download/3.5.0/StereoPipeline-3.5.0-2025-04-28-x86_64-Linux.tar.bz2

      
      

   2. tar -xvf StereoPipeline-3.5.0-2025-04-28-x86_64-Linux.tar.bz2

5. cd StereoPipeline-3.4.0-2024-06-19-x86_64-Linux/

6. LD_LIBRARY_PATH=$PWD/lib bin/dem_geoid --help

7. LD_LIBRARY_PATH=$PWD/lib bin/dem_geoid /mnt/{path_to_dem}.tif --reverse-adjustment

   
   

   1. Reverse AdjustmentTransforms DEM from MSL to NAD83 Ellipsoid Height

8. ls

   
   

   1. To locate new filename

9. mv ./{newFilename} /mnt/{newFilePath}