External DEM format

I want to use an external DEM for my interferometry analysis. The external DEM is in WGS84, Geotif.format
Should the DEM be in the “Geoid” or the “Spheroid (ellipsoid)” format? does it make any differnece?
Best regards

could you please clarify: Do you want to include it for topographic phase removal or terrain correction?
At which point of your preprocessing do you have to chose between geoid or ellipsoid?

Terrain Correction allows to apply EGM96, for example when working with the TanDEM-X elevation model.

Hi Braun,
thanks for your quick reply.
for “phase to elevation” process for example.
So, is it correct to use the external DEM in ellipsoid, and then apply EGM, for converting the results into Geoid, or shall I use DEM in Geoid from the beginning? (for topographic phase removal for example). The dataset is Sentinel-1.
thanks for your reply

that depends on if your external DEM is geoid corrected (does it contain true elevations above sea level) or not.

the external DEM is available in both geoid and ellipsoid. That is why I am wondering which one is more suitable to be used!

now I understand… Then I recommend the geoid one (without the EGM96 option)

Thanks Braun,
You are right; I did a test with both options (geoid vs. ellipsoid), and the goid one gave me more relaible results. Which also confirms your suggestion.