[Proj] EPSG:28992 to EPSG:23031 conversion

[Jean-Claude Repetto]

bartvde at osgis.nl wrote :

> when I use PROJ.4 to do a conversion between EPSG:28992 (the Dutch
> national grid) and UTM zone 31 ED50 I get:
> 
> cs2cs -f %.9f +proj=sterea +lat_0=52.15616055555555
> +lon_0=5.38763888888889 +k=0.999908 +x_0=155000 +y_0=463000 +ellps=bessel
> +units=m
> +towgs84=565.2369,50.0087,465.658,-0.406857330322398,0.350732676542563,-1.8703473836068,4.0812
> +no_defs +to +proj=utm +zone=31 +ellps=intl +units=m +no_defs
> 19465 394814
> 530108.861080788        5708613.329898705 -150.818087836
> 
> 
> Northing 5708615,754
> Easting 530199,479
> 
> so especially the difference in easting is too large.
> 
> Is there a logical explanation for this difference? TIA.

Hi Bart,

I think you have forgotten the +towgs84 parameters to do the WGS84 -> 
ED50 transformation.

Jean-Claude