[Gvsig_english] Problems with EPSG.21781

Frank Warmerdam warmerdam at pobox.com
Wed Nov 4 17:20:43 CET 2009


Benjamin Ducke wrote:
> The error message comes directly from the PROJ4 library which
> gvSIG uses to reproject from one SRS into another.
> Unfortunately, PROJ4 documentation is quite horrible and fragmentary,
> so I could not get down to the root of this issues.
> There are, however some notes on the Swiss Mercator projection:
> 
> ftp://ftp.remotesensing.org/proj/swiss.pdf
> 
> It seems that +init=world:CH1903 is needed to initialize PROJ4
> with that projection? Perhaps there is something that was overlooked
> when rewriting the SRS engine for 1.9? I think this needs fixing
> by the developers.
> 
> In the meantime, you could use the new tools in gvSIG 1.9 to define
> a custom SRS. Just use the same parameters as EPSG 21781, expect
> that you need to set azimuth to something very close to 90.0
> (like 89.9999, as suggested in the link you mentioned).

Folks,

I examined the current PROJ.4 epsg init file and for 21781 it uses:

# CH1903 / LV03
<21781> +proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 
+x_0=600000 +y_0=200000 +ellps=bessel +towgs84=674.374,15.056,405.346,0,0,0,0 
+units=m +no_defs  <>

I have tried this and do not get the mentioned error.  I believe there was
an error in the epsg init file in some versions of PROJ.4 so replacing
the <21781> entry in the init file will hopefully correct the issue
till it is upgraded.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent



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