Am 16.09.2015 um 12:15 schrieb Bernhard Ströbl: > hope this helps
It seems my question was not very clear, so in other words (all "as far as I understand"): When I create a shapefile with CRS 3857 (Pseudo Mercator), and upload it to the cartodb web service, the features are shifted. I tried to inspect this and could reproduce the same behaviour in QGIS itself: QGIS creates two files for projection with two forms of WKT, which should express the same projection: .prj: PROJCS["WGS_84_Pseudo_Mercator",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Mercator"],PARAMETER["central_meridian",0],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["Meter",1],PARAMETER["standard_parallel_1",0.0]] .qpj: PROJCS["WGS 84 / Pseudo-Mercator",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Mercator_1SP"],PARAMETER["central_meridian",0],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs"],AUTHORITY["EPSG","3857"]] To reproduce the problem with cartodb, I deleted the qpj file (as other applications are expected to ignore this suffix) and loaded the shapefile into QGIS. The layer properties then show EPSG 54004 World Mercator and I see the same shift as in cartodb. The coordinate 774575/6610921, which marks Cologne Cathedral in 3857, is projected into a lake near Duesseldorf. So I think there is something wrong either with the shorter WKT, or how it is interpreted by QGIS or GDAL/OGR. Once you know this, a workaround is obvious. I hope with your help we can describe the error more precisely to make an informed bug report. Am 16.09.2015 um 12:15 schrieb Bernhard Ströbl: > Hi, > > general: read the documentation on projections, be sure to know what > projections are and what they are used for. > > specific: both your project and your data have a projection (spatial > reference system). Cases: > 1) both match => you're ok > 2) both differ => QGIS can reproject the data on-the-fly => you're ok > 3) the projection assigned to the data is wrong (I assume this is your > case but without more info on what you do nobody can tell). Tell QGIS in > layer properties which projection your data is in (the prj and qpj files > do just that), then goto either case 1 or case 2 > > hope this helps > > Bernhard > > Am 16.09.2015 um 11:46 schrieb Redoute: >> This question is arising from >> http://gis.stackexchange.com/questions/162779/why-is-the-city-of-san-francsico-floating-over-point-richmond >> >> I create a shapefile in QGIS in CRS 3857. I delete the .qpj file and >> load the shapefile again. The features then are placed wrong, the >> Cologne Cathedral shows up in a lake near Duesseldorf :-((. So I reason >> there is something wrong with the .prj file. >> >> What is it? Is it a bug in GDAL/OGR? >> Tested with QGIS 2.10.1. _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
