[gdal-dev] how to use the -ct option in ogr2ogr

Tue Feb 9 00:15:23 PST 2021

the projinfo-command was exactly what i needed but didn't know it 
exists! the ogr2ogr -ct command works now, thank you very much!

could this example be added to the official examples on 
https://gdal.org/programs/ogr2ogr.html#ogr2ogr ? i think the -ct option 
is very useful and an example for it would be good. i could also try to 
edit it on my own and send a pull request if that helps

i just like to use the console if i can, QGIS has it's advantages but if 
i have the option to use gdal directly or via a wrapper like QGIS, i 
like to use gdal directly. this also saves me from the pain when the 
wrapper does implement something wrong or uses it's own functions 
instead of gdal, which in addition could change every new version and 
need to be checked. using gdal directly is much more reliable for me.

Am 08.02.2021 um 22:18 schrieb Markus Metz:
>
>
> On Mon, Feb 8, 2021 at 10:23 AM Karsten Tebling <tebling at masuch.de 
> <mailto:tebling at masuch.de>> wrote:
> >
> > gdalinfo for NTv2LSBB_LSA.gsb gave the following information:
> >
> > Size is 256, 264
> > Coordinate System is: EPSG 4326
> > Origin: 10.5, 53.1
> > SYSTEM_F: S4283
> > SYSTEM_T: ETRS89
> > Upper Left 10.5, 53.1
> > Lower Left 10.5, 50.9
> > Upper Right 13.3, 53.1
> > Lower Right 13.3, 50.9
> >
> > ogrinfo for punkte_31468.dxf gave the following information:
> >
> > Geometry: Unknown (any)
> > Feature Count: 36
> > Extent: (4523806.5, 5758974.7) - (4524134.7, 5759234.0)
> > Layer SRS WKT: (unknown)
> >
> > according to QGIS punkte_31468.dxf should be at 11.6 52.1 which is 
> inside the extent of the NTv2LSBB_LSA.gsb. after checking the 
> documentation for the NTv2LSBB_LSA.gsb i noticed i couldn't use it for 
> transformations from 31468 to 25833, that's why i tried it with 
> BETA2007.gsb instead, but it didn't work either - it gave the same errors.
> >
> > gdalinfo for BETA2007.gsb gave the following information:
> >
> > Size is 62, 84
> > Coordinate System is: EPSG 4326
> > Origin: 5.4, 55.4
> > SYSTEM_F: DHDN90
> > SYSTEM_T: ETRS89
> > Upper Left 5.4, 55.4
> > Lower Left 5.4, 47.0
> > Upper Right 15.8, 55.4
> > Lower Right 15.6, 47.0
> >
> > my adjusted code for BETA2007.gsb looks like:
> >
> > ogr2ogr -s_srs "EPSG:31468" -t_srs "EPSG:25833" -dim XYZ -ct 
> "+proj=pipeline +step +inv +proj=tmerc +lat_0=0 +lon_0=12 +k=1 
> +x_0=4500000 +y_0=0 +ellps=bessel +step +proj=hgridshift 
> +grids=BETA2007.gsb +step +proj=utm +zone=33 +ellps=GRS80" -f DXF 
> punkte_25833.dxf punkte_31468.dxf
> >
> > the points i used to test this were digitized around Magdeburg, 
> Saxony-Anhalt in EPSG:31468. according to aerial data and 
> openstreetmap, the position and coordinate system are correct when i 
> check it in QGIS and switch to different coordinate systems.
>
> Wit PROJ 7.2.1 and
> projinfo -o PROJ -s "EPSG:31468" -t "EPSG:25833"
> I get
> Operation No. 1:
>
> unknown id, Inverse of 3-degree Gauss-Kruger zone 4 + DHDN to ETRS89 
> (8) + UTM zone 33N, 0.9 m, Germany - onshore - states of 
> Baden-Wurtemberg, Bayern, Berlin, Brandenburg, Bremen, Hamburg, 
> Hessen, Mecklenburg-Vorpommern, Niedersachsen, Nordrhein-Westfalen, 
> Rheinland-Pfalz, Saarland, Sachsen, Sachsen-Anhalt, 
> Schleswig-Holstein, Thuringen.
>
> PROJ string:
> +proj=pipeline
>   +step +proj=axisswap +order=2,1
>   +step +inv +proj=tmerc +lat_0=0 +lon_0=12 +k=1 +x_0=4500000 +y_0=0
>         +ellps=bessel
>   +step +proj=hgridshift +grids=de_adv_BETA2007.tif
>   +step +proj=utm +zone=33 +ellps=GRS80
>
> -------------------------------------
> Operation No. 2:
>
> unknown id, Inverse of 3-degree Gauss-Kruger zone 4 + DHDN to ETRS89 
> (2) + UTM zone 33N, 3 m, Germany - states of former West Germany 
> onshore - Baden-Wurtemberg, Bayern, Bremen, Hamburg, Hessen, 
> Niedersachsen, Nordrhein-Westfalen, Rheinland-Pfalz, Saarland, 
> Schleswig-Holstein.
>
> PROJ string:
> +proj=pipeline
>   +step +proj=axisswap +order=2,1
>   +step +inv +proj=tmerc +lat_0=0 +lon_0=12 +k=1 +x_0=4500000 +y_0=0
>         +ellps=bessel
>   +step +proj=push +v_3
>   +step +proj=cart +ellps=bessel
>   +step +proj=helmert +x=598.1 +y=73.7 +z=418.2 +rx=0.202 +ry=0.045 
> +rz=-2.455
>         +s=6.7 +convention=position_vector
>   +step +inv +proj=cart +ellps=GRS80
>   +step +proj=pop +v_3
>   +step +proj=utm +zone=33 +ellps=GRS80
>
>
> It seems your custom definitions of the coordinate operation are 
> missing the axis swap step "+step +proj=axisswap +order=2,1".
> According to "projinfo -o WKT2:2019 "EPSG:31468", northing is the 
> first axis in EPSG:31468, thus the need for the axis swap.
>
> If you trust the QGIS coordinate operation, then why do you provide a 
> custom coordinate operation to ogr2ogr with the -ct option?
>
> >
> > Am 06.02.2021 um 22:24 schrieb Markus Metz:
> >
> >
> >
> > On Fri, Feb 5, 2021 at 3:40 PM Karsten Tebling <tebling at masuch.de 
> <mailto:tebling at masuch.de>> wrote:
> > >
> > > Hello,
> > >
> > > i'm struggling with how to use the -ct option in ogr2ogr and could 
> need
> > > some help.
> > >
> > > i copied a NTv2.gsb to osgeo4w64/share/proj and edited the proj.db by
> > > inserting a new row in the grid_transformation-table. using this
> > > transformation in qgis works. however when i try to use it in ogr2ogr
> > > with the same data i always get "failed to reproject feature (geometry
> > > probably out of source or destination srs). no known way to write
> > > feature with geometry 'none'". here is my code:
> > >
> > > ogr2ogr -s_srs "EPSG:31468" -t_srs "EPSG:25833" -dim XYZ -ct
> > > "+proj=pipeline +step +inv +proj=tmerc +lat_0=0 +lon_0=12 +k=1
> > > +x_0=4500000 +y_0=0 +ellps=bessel +step +proj=hgridshift
> > > +grids=NTv2LSBB_LSA.gsb +step +proj=utm +zone=33 +ellps=GRS80" -f DXF
> > > punkte_25833.dxf punkte_31468.dxf
> > >
> >
> > Is the grid NTv2LSBB_LSA.gsb used for hgridshift really covering the 
> full extent of punkte_31468.dxf ?
> > You can check with "gdalinfo NTv2LSBB_LSA.gsb" and "ogrinfo -so 
> punkte_31468.dxf".
> >
> > Markus M
> >
> > > i'm using the latest qgis-ltr and osgeo4w shell
> > >
> > > greetings
> > > _______________________________________________
> > > gdal-dev mailing list
> > > gdal-dev at lists.osgeo.org <mailto:gdal-dev at lists.osgeo.org>
> > > https://lists.osgeo.org/mailman/listinfo/gdal-dev 
> <https://lists.osgeo.org/mailman/listinfo/gdal-dev>
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