[gdal-dev] Transformation works in GDAL2 but cause problems in GDAL3

[Even Rouault]

Mattijn,

> Question: how do I define my source raster instance, to avoid using the
> advance `-ct` operator in gdalwarp in GDAL3 during reprojection?

I don't think you can avoid it here. There seems to be an issue in either your 
source file or in the HDF5 driver regarding the unit of the ellipsoid axis. 
Normally the a and b parameters should be in meters, not kilometers.

> But now with GDAL3 using the same command I get:
> 
> ERROR 1: PROJ: proj_create_operations: Source and target ellipsoid do not
> belong to the same celestial body

yes it detects that the source and target ellipsoids are completely different, 
which is in most cases involve a non sensical attempt.

> And using the `-ct` operator with GDAL3 I get this:
> 
> echo "0.000 -3650.000" | gdaltransform -s_srs '+proj=stere +x_0=0 +y_0=0
> +lat_0=90 +lon_0=0 +lat_ts=60 +a=6378.137 +b=6356.752' -t_srs EPSG:4326 -ct
> '+proj=axisswap +order=2,1 +step' --debug on

Your -ct pipeline should include the full pipeline, not just an axisswap 
operation. For gdaltransform, you can remove the -s_srs and -t_srs parameters 
when you specify -ct. For gdalwarp / ogr2ogr, you can keep the -t_srs so that 
the output dataset has correct CRS information.

Your pipeline should be something like

+proj=pipeline +step +inv +proj=stere +x_0=0 +y_0=0
+lat_0=90 +lon_0=0 +lat_ts=60 +a=6378.137 +b=6356.752 +step +proj=axisswap 
+order=2,1

Even

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