Can somebody explain why the result of osr.SpatialReference() differ between Python 2 and 3?

sr = osr.SpatialReference()

In Python 2.7 this gives me

Out[15]: '+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725 +units=m +no_defs '

In Python 3 though, I get a different answer:

Out[14]: '+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.2369,50.0087,465.658,-0.406857,0.350733,-1.87035,4.0812 +units=m +no_defs'

The projections differ in the datum shift values for the conversion from Amersfoort datum to WGS84.

The first one is tfm code 4833, and the second is tfm code 15934.

GDAL 2.1.0 uses tfm code 4833, while GDAL 2.2.0 and later uses tfm code 15934. The change was done in https://trac.osgeo.org/gdal/changeset/37081

According to the remarks, 4833 is the latest definition. See also https://trac.osgeo.org/gdal/ticket/2487 for the difference.

If you want higher precision, you could use a grid shift file for the transformation, see http://osgeo-org.1560.x6.nabble.com/Amersfoort-RD-New-td5293753.html

  • so his system uses different gdal versions? – nickves Nov 16 '18 at 11:12
  • Unless they compiled the Python bindings themselves, that seems likely. – bugmenot123 Nov 16 '18 at 12:29
  • Excellent answer. – LarsVegas Nov 16 '18 at 18:32
  • 1
    @bugmenot123 it is not necessary to compile the Python bindings yourself, you can just exchange the csv files to get the transformation synchronous in both pythons. – AndreJ Nov 19 '18 at 10:36

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