[gdal-dev] gdalwarp and gdaltransform are inconsistent

[jratike80]

I would like to add that the command that you used

gdalwarp -t_srs EPSG:4326 -s_srs EPSG:2056
SWISSALTI3D_10_TIFF_CHLV95_LN02_2600_1196.tif test.tif

of course must not alter the pixel values. There are other sort of single
band raster files than DEMs and it would make no sense at all to apply datum
shifts to temperatures, pressures, slopes and so on.

-Jukka-


jratike80 wrote
> Hi,
> 
> When it comes to gdalwarp I believe that this part of the documentation
> https://gdal.org/programs/gdalwarp.html is essential
> 
> "Starting with GDAL 2.2, if the SRS has an explicit vertical datum that
> points to a PROJ.4 geoidgrids, and the input dataset is a single band
> dataset, a vertical correction will be applied to the values of the
> dataset."
> 
> Both EPSG:4326 and EPSG:2056 are 2D systems without explicit vertical
> datum.
> EPSG:4979 is explicit 3D  
> http://www.epsg-registry.org/export.htm?wkt=urn:ogc:def:crs:EPSG::4979 and
> the compound crs syntax that you used (-s_srs EPSG:2056+5728) is explicit
> as
> well.
> 
> I do not know how gdaltransform knows to do the conversion in Z coordinate
> and how to give the -s_srs and -t_srs right for gdalwarp but I would try
> next with
> -s_srs EPSG:2056+5728 -t_srs epsg:4979
> 
> -Jukka Rahkonen-





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