[Qgis-developer] Unexpected change in ESPG codes from shapefiles (in stable and dev)
ouyang.leyan.ml at hotmail.com
Thu Dec 18 12:23:41 PST 2014
On 12/18/2014 06:35 PM, Kari Salovaara wrote:
> in Finland we have map datasets free of charge to download from The
> National Land Survey of Finland (NLS). See
> From Topographic Database You can download in ESRI shape format any
> Finnish map area. In each area You'll get a number of shapefiles
> related to category and each category has also a *.prj file.
> The problem arises when You make a layer from any of these shapefiles
> in following example;
> 1. set project CRS to Finnish ESPG:3067 ( which is on the list
> EPSG:3067 - ETRS89 / ETRS-TM35FIN)
> 2. make a layer from shapefile, as it has *.prj which starts like
> You expect the layer CRS to be 3067 but when You look to layer
> properties it shows 3047 (in the dialog list EPSG:3047 - ETRS89 /
> (which means, I think,
> small but nasty difference.
> This problem can cause difficulties when creating scripts for
> automation etc.
> And very odd is that when You have created an empty project with CRS
> set to 3067 and create a shapefile its *.prj file starts
> but in this case the EPSG is 3067.
> For my knowledge ETRS-TM35FIN is always and only EPSG:3067.
> Could someone explain is this failure in QGIS or GDAL/OGR or PROJ.4?
> This problem has been tested in 2.6.1 (latest update in OpenSuse12.3)
> and 2.7.0 (nightly) versions and both linux and win 7 environments.
> Finnish QGIS society are waiting this Christmas Question answer with
> interest. ;)
> With warm and kind regards,
> PS. This has been discussed here locally without any final
> understanding. Some guess has been that program only looks and takes
> first some nearly suitable code and uses it.
It seems the proj4 string for both CRS is the same in my local
installation. Is it the same for you ? In that case, they are exactly
equivalent for QGis. When QGis finds a dataset without a clear CRS code,
it will parse the proj4 string to find the coordinate system and stop at
the first corresponding one.
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