Hi again,
----- Mensagem original ----- > DE: Pedro Venâncio > > >>>> However I came across something quite odd. In the Datum > Transformation window, automatically arise some strange transformations (red > in > the image http://goo.gl/iIWOuw). These transformations give huge errors, and > I > do not understand what they represent. > >>> QGIS reads all possible combinations to get from one datum to the > other. Seems to me these towgs84 transformations are all present in the > transformation table > > No, those parameters that have +towgs84=565.04(...) are not associated with > any > portuguese transformation. These parameters belong to epsg_nr 1571. The only > point of contact between this entry and the portuguese entries, is that both > uses 4258 (Geographic CRS ETRS89). epsg_nr 1571 uses it as source_crs_code, > and > some transformations for Portugal (ntv2 grids transformations) uses it as > target_crs_code. > > >>> (though I don't know . Is it 4258?) > > The biggest mess in my mind is precisely this. Is that, even the possible > incorrect match between source and target codes does not make sense, because > the > geographical crs related to 30004 is 4326 (+towgs84). We only use 4258 for > ntv2 > grids. > > So, these options in red in the image should not show up. I think this > problem > only happens with the portuguese transformations, right Giovanni? > > I can now confirm that it is a conflict with epsg_nr 1571, because deleting this record delete from tbl_datum_transform where epsg_nr = 1571; the problem disappears. Best regards, Pedro _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
