Datum Transformation might be a reason. Different implementations of the calculation could also account for it. https://trac.osgeo.org/gdal/wiki/FAQCoordinateSystemsAndProjections#WhydoesntGDALautomaticallychoosethedatumtransformation https://github.com/OSGeo/proj.4/wiki https://github.com/OSGeo/proj.4/wiki/GenParms (Datum Transformations)
There is always some accuracy/precision loss reprojecting too. Which UTM Zone 32 proj did you use? If you really want to see the code, it's in the PROJ4 project. Enjoy, Alex On 11/12/2015 10:01 AM, francesco_lucca wrote: > Hi, > I have a point in WGS84 UTM32 coordinate > > E 589747.816 > N 4871699.496 > > I saved in EPSG 3003 with the following coordinates: > > E 1589776.553 > N 4871716.117 > > A colleague made the same conversion using free software "traspunto" > (http://www.mondogis.com/traspunto.html) developed by the Italian > Enviromental Ministry. He got this result (EPSG 3003 coordinates): > > E 1589776.054 > N 4871716.382 > > I try another online tool > (http://www.sardegnageoportale.it/webgis/raswebconverter/index?stato_quale=punto) > and I found these EPSG3003 coordinates: > > E 1589776.554 > N 4871716.119 > > Summary: QGIS and sardegnageoportale seem to give the same results, > traspunto is different (0.50 meter difference). Which is the correct result? > Where can I found the calculation for the conversion from a system to > another? > > Thanks > > Francesco > > > > -- > View this message in context: > http://osgeo-org.1560.x6.nabble.com/coordinate-conversion-tp5236051.html > Sent from the Quantum GIS - User mailing list archive at Nabble.com. > _______________________________________________ > Qgis-user mailing list > Qgis-user@lists.osgeo.org > List info: http://lists.osgeo.org/mailman/listinfo/qgis-user > Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user > _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: http://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: http://lists.osgeo.org/mailman/listinfo/qgis-user
