[gdal-dev] Vertical datum conversion for SRTM data

[Michael Smith]

Egm96 grid shift file available from http://download.osgeo.org/proj/vdatum/egm96_15/egm96_15.gtx

 

Mike

 

 

-- 

Michael Smith

Remote Sensing/GIS Center

US Army Corps of Engineers

 

From: gdal-dev <gdal-dev-bounces at lists.osgeo.org> on behalf of Even Rouault <even.rouault at spatialys.com>
Date: Tuesday, November 21, 2017 at 6:18 AM
To: <gdal-dev at lists.osgeo.org>
Subject: Re: [gdal-dev] Vertical datum conversion for SRTM data

 

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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