[Proj] truble to translate coordinates from WGS84 to EPSG:31287

[Jean-Claude Repetto]

Le 28/10/2010 10:11, Markus Hetzmannseder a écrit :
> Hallo,
>
> i have trubles to translate WGS84 coordinates to EPSG:31287. This is
> needed at the Openstreetmap Projekt for the correct projection of OSM-data
> to the austrian geoimage.at WMS-service. For the OSM-editor JOSM there is
> a plugin epsg31287, that should do the job and in its calculations it is
> based on proj. That plugin is based an proj is working, its not working
> really correct. It is producing a shift of about 30 metre and that shift
> is only local, in other regions of austria the shift has a different
> length and different direction.
>
> For debugging that shift i started to use proj directly, and it is
> producing the same shift in its calculations like the JOSM-plugin.
>
>
> The correct proj arguments for EPSG31287 should be:
> +proj=lcc +lat_1=49 +lat_2=46 +lat_0=47.5 +lon_0=13.33333333333333
> +x_0=400000 +y_0=400000 +ellps=bessel
> +towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232
> +units=m +no_defs
>
> For my reference i use the coordinate translation service of geoland.at
> (http://www.geoland.at/geolandcoord/eingabe.aspx)
>
> The results are for some example points:
>
> WGS84                    proj-EPSG31287               geoland.at-EPSG31287
> 14.2833092 48.3098392    470439.28	490437.40     470507.17  490503.03
> 16.371345 48.211996      625637.33	483542.58     625724.57  483601.75
> 9.747076 47.503042       130035.17	406569.01     130056.24  406637.26
>
> The geoland.at projection is, as far i know, the real projection the
> WMS-service (http://wms.geoimage.at) is using.
>
>
> Any hints where the difference could be come from?
>
> thx a lot
> Markus Hetzmannseder
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Hello,

I get the same results as geoland.at :

  cs2cs +init=epsg:4326 +to +proj=lcc +lat_1=49 +lat_2=46 +lat_0=47.5 
+lon_0=13.33333333333333 +x_0=400000 +y_0=400000 +ellps=bessel 
+towgs84=577.326,90.129,463.919,5.137,1.474,5.297,2.4232 +units=m +no_defs
14.2833092 48.3098392
470507.17	490503.01 -45.92
16.371345 48.211996
625724.58	483601.74 -44.45
9.747076 47.503042
130056.92	406637.21 -48.36

Jean-Claude