EGM96 and EGM2008 Geoids

Geoid models created by NGA as a grid.  These have the height above the ellipsoid in meters, and should range up to approximately 100 m in absolute value.

EGM2008

EGM96


Using in MICRODEM

The grids are downloaded with the geology download, and then files will be in  available in  C:\mapdata\geology\geology_grids


GEOID12B_CONUS

GEOID 18 US

GDAL reads a number of the grid shift files needed for the vertical datum shifts:


References


Last revision 6/4/2020