Generating_DEM

Methods and Sources for Generating DEM Files

Here we list some available methods for generating and downloading Digital Elevation Model (DEM) files for InSAR processing.

  • Generating DEM through the GMTSAR topex server

  • Generating DEM through GMT via GMTSAR script make_dem.csh

Generating DEM through topex server

To download a maximum 4x4º size grid of DEM from SRTM1, SRTM3 or ASTER-1 visit the website: https://topex.ucsd.edu/gmtsar/demgen/

Enter your chosen latitude and longitude boundaries and your preferred DEM source and click “Generate”.

Once the request is finished you can download the zipped file. (Sometimes you need to right-click to download as a file).

  • NOTE: If you area crosses the equator, you may need to download each area above and below the equator separately and then paste them together (check out GMT grdpaste to do so)

  • NOTE: If you need a larger than 4x4deg area, you can always download smaller areas and paste them together with GMT grdpaste

Generating DEM via GMT

This uses the GMTSAR script make_dem.csh which uses the GMT server to download SRTM 1-arcsecond data (@earth_relief_01s) and removes the EGM96 geoid to make heights relative to WGS84.

To run, you need to know your region of interest’s latitude and longitude bounds

make_dem.csh -122 -115 32 36

This will output a dem.grd, with heights relative to the WGS84 ellipsoid