>From a quick look on epsg.io there seems not to be a direct transform from *27572 *to* 2154 *so that is why the TOWGS or Bursa Wolf transform is needed. These would appear to have a 2m accuracy so some transformation error is to be expected.
If you have a grid shift or other transformation file available then you can add it to GeoTools as described here - https://gis.stackexchange.com/questions/313512/specifying-epsg-transformation-method-in-geotools/313523#313523 Ian On Mon, 15 Jul 2024 at 01:31, Mourad HARMIM <mourad.har...@live.fr> wrote: > Hello everyone, > I hope this message finds you well. > > My name is Mourad Harmim, a Data Engineer consultant from France. > Still getting used to GeoTools, I’m facing an issue when I try to > transform coordinates from *Lambert 2 extended (EPSG :27572) to Lambert > 93 (EPSE :2154).* > > Here is my current situation : > > - When I use : *this.mathTransform = > CRS.findMathTransform(CRS.decode("EPSG:27572") , CRS.decode("EPSG:2154"), > false)* there is an error telling that Bursa Wolf parameters are > missing > - When I use : *this.mathTransform = > CRS.findMathTransform(CRS.decode("EPSG:27572") , CRS.decode("EPSG:2154"), > true)* I get coordinates but they seem inaccurate (I guess it is about > a missing grid shift) > - When I use intermediate system : *Lambert 2 extended (EPSG :27572) > to WSG84 (EPSG:4326) to Lambert 93 (EPSE :2154)* I get better results > but still inaccurate. > > > I would like to know what it is the correct approch to have an accurate > transformation between these two systems. > > I hope that it is not inappropriate to ask for your help through this > email and I hope to hear from you soon. > Thank you. > Mourad Harmim. > _______________________________________________ > GeoTools-Devel mailing list > GeoTools-Devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/geotools-devel > -- Ian Turton
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