[Qgis-user] Coordinate transformations

[Antonio Valanzano]

I have tried to transform the coordinates of a single point (541000,
4516000) with epsg:23033 into 2 other coordinate systems (epsg:25833 e
6708).

I have done these transformations using 2 different methods: DB Manager
(with an sql script)  and export layer.

However the results of these transformations are different.
I know that DB Manager uses the Spatialite engine for processing the sql
script and the results are the same as those obtained using Spatialite or
PostGIS (both based on Proj lib).

I do not know how the export layer method produces the results.

I expected the same results but this is not true.

Does someone know more detailed information about this subject ?

Here the details of the transformations

 Punto di partenza ED50/UTM zone 33N (epsg:23033)

X Y

541000 4516000






da 23033 a 25833 (ETRS89/UTM zone 33N)
X_Spatialite 540998,138333   Y_Spatialite 4515921,565375
X_PostGIS 540998,138333   Y_PostGIS 4515921,565375


X_QGIS_DB_Manager 540998,138333   Y_QGIS_DB_Manager 4515921,565375
X_QGIS_export_layer 540931,341497   Y_QGIS_export_layer 4515810,597826










da 23033 a 3065  (IGM95/UTM zone 33N)
X_Spatialite 540927,563731   Y_Spatialite 4515811,141068
X_PostGIS 540927,563731   Y_PostGIS 4515811,141068


X_QGIS_DB_Manager 540927,563731   Y_QGIS_DB_Manager 4515811,141068
X_QGIS_export_layer 540998,138333   Y_QGIS_export_layer 4515921,565375










da 23033 a 6708  (RDN2008/UTM zone 33N)
X_Spatialite 540927,563731   Y_Spatialite 4515811,141068
X_PostGIS 540927,563731   Y_PostGIS 4515811,141068


X_QGIS_DB_Manager 540927,563731   Y_QGIS_DB_Manager 4515811,141068
X_QGIS_export_layer 540998,138333   Y_QGIS_export_layer 4515921,565375

Thanks in advance

Antonio Valanzano
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