[gdal-dev] Failure with osr.CoordinateTransformationOptions()

[Stefano Iacovella]

Hi Even,

Thank you for your detailed reply.
So if I want to use 1169 or also 1660, that is the first candidate listed by

projinfo -s EPSG:3003 -t EPSG:4326 --spatial-test intersects

I can transform the coordinates from 3003 to 4265, that is the geodetic SRS
used by 3003

sourceProj = osr.SpatialReference()
sourceProj.ImportFromEPSG(3003)

sourceGeo = osr.SpatialReference()
sourceGeo.ImportFromEPSG(4265)

proj2geo = osr.CoordinateTransformation(sourcePro,sourceGeo)

point.Transform(proj2geo)

then I can use EPSG:1169. I tried the code snippet and it seems to be
working properly.
Do you think this is a correct approach?

All the best

Stefano


Il giorno ven 5 mar 2021 alle ore 12:11 Even Rouault <
even.rouault at spatialys.com> ha scritto:

> Stefano,
>
> urn:ogc:def:coordinateOperation:EPSG::1169 is a transformation between
> EPSG:4265 (the geographic CRS of Monte Mario) and EPSG:4326. You cannot use
> it directly when the source CRS is EPSG:3003, which is a projected CRS
> based on EPSG:4265.
>
> You could instead use
>
> options.SetOperation("""+proj=pipeline
>   +step +inv +proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=1500000 +y_0=0
>         +ellps=intl
>   +step +proj=push +v_3
>   +step +proj=cart +ellps=intl
>   +step +proj=helmert +x=-225 +y=-65 +z=9
>   +step +inv +proj=cart +ellps=WGS84
>   +step +proj=pop +v_3
>   +step +proj=unitconvert +xy_in=rad +xy_out=deg
>   +step +proj=axisswap +order=2,1""")
>
> as suggested by the output of projinfo -s EPSG:3003 -t EPSG:4326
> --spatial-test intersects
>
> Even
> Le 05/03/2021 à 09:42, Stefano Iacovella a écrit :
>
> Hi all,
>
> I am trying to use GDAL, via Python bindings, to convert coordinates.
> I would like to select a specific transformation when converting among CRS
> with different Datums. Reading the documentation my understanding is that I
> need to create a osr.CoordinateTransformation with options parameter
> valorized properly.
> I am using binaries from OSGEO4WIN, the release are 3.1.4 for GDAL and
> 6.3.2 for PROJ
> This is a code snippet I am using to debug:
>
> from osgeo import ogr
> from osgeo import osr
>
> source = osr.SpatialReference()
> source.ImportFromEPSG(3003)
>
> target = osr.SpatialReference()
> target.ImportFromEPSG(4326)
>
> options = osr.CoordinateTransformationOptions()
> options.SetOperation("urn:ogc:def:coordinateOperation:EPSG::1169")
> transform = osr.CoordinateTransformation(source, target, options)
>
> point = ogr.CreateGeometryFromWkt("POINT (1622987 4756952)")
> point.Transform(transform)
>
> print point.ExportToWkt()
>
> I have no errors running it but the coordinates of the point, after the
> transformation, are infinite. If I create the CoordinateTransformation
> without options like this:
>
> transform = osr.CoordinateTransformation(source, target)
>
> The point coordinates after transformation are ok but of course the
> conversion is performed using the Coordinate Operation automatically
> selected by the system.
> Am I doing something wrong?
>
> Thank you in advance for your help.
>
> All the best,
>
> Stefano
>
>
> _______________________________________________
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>
> -- http://www.spatialys.com
>
>
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