[Qgis-developer] custom prj

[Martin Dobias]

On Tue, Mar 3, 2009 at 11:10 AM, Paolo Cavallini <cavallini at faunalia.it> wrote:
> Hi all.
> Apparently newer versions of QGIS have problems reading custom
> projection files (see attached).
> In one of the IT regions, the administrations use a custom projection
> system, with a False_Northing at -4000000 (I know it is stupid).
> QGIS 0.9.2 can read it and reproject it, whereas 1.0 fails.
> Probably the newer versions check whether the prj corresponds to a EPSG
> projection, and in case it is not it refuses considering it, but IMHO it
> should just warn the user ("non standard projection") and proceed.
> Am I missing something?

Hi Paolo,

in case it's an unknown projection, QGIS just fails to use it. To work
this around, add that projection to the custom projections with these
parameters:
+proj=tmerc +lat_0=0 +lon_0=9 +k=0.9996 +x_0=500000 +y_0=-4000000
+ellps=intl +units=m +no_defs
Next time you load the layer, the reference system will be detected
correctly and you'll be able to project it.

I agree that this is not user-friendly. A solution might be to tell
the user that we have an unknown reference system and ask him whether
he would like to add it (otherwise it won't work).

Martin