[gdal-dev] Vertical datum conversion for SRTM data

[Even Rouault]

On mardi 21 novembre 2017 10:25:42 CET Nikos Alexandris wrote:
> Dear list, can GDAL handle the following exercise?
> 
> Of interest is the Mean Sea Level, based on NASA’s SRTM. I am new in this
> topic. Is the following equation correct?
> 
> SRTM(MSL) = SRTM(WGS84) - MSL(WGS84) [*]
> 
> 
> Is it “correct” to recommend the https://hydrosheds.cr.usgs.gov/ data
> set for Mean Sea Level related studies? I refer specifically to i) 5.1
> Void-filled digital elevation model  and ii) 5.2 Hydrologically conditioned
> elevation [**]

Not completely sure this answers your questions ,but this is related.

Quoting end of http://www.gdal.org/gdalwarp.html:

"""
    (GDAL >= 2.2) To transform a DEM from geoid elevations (using EGM96) to WGS84 ellipsoidal heights:

gdalwarp -overwrite in_dem.tif out_dem.tif -s_srs EPSG:4326+5773 -t_srs EPSG:4979
"""

This assumes the egm96_15.gtx grid is in the proj.4 resource directory.

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