[Gdal-dev] bessel to wgs84?

[Frank Warmerdam]

On 5/23/05, Kees Krikke <c.krikke at hccnet.nl> wrote:
>  
> Hello, 
>   
> I'm trying to reproject some images from the Dutch RD coordinate system
> (epsg:28992) that is defined as: 
>   
> +proj=stere +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.999908
> +x_0=155000 +y_0=463000 +ellps=bessel +units=m  +no_defs 
>   
> to utm zone 31N /wgs84 
> +proj=utm +zone=31 +datum=wgs84 
>   
> For the datum shift i guess i need to specify the +towgs argument also with
> the source coordinate system.
> (+towgs=565.04,49.91,465.84,-0.409394387,0.35970519561,-1.868491) 
>   
> I verified these values by running proj.exe and the results are ok. 

Kees, 

Note that proj.exe ignores the +towgs84 specification.  If you want something
analygous to what gdalwarp will do, then you should use cs2cs. 

eg. 

cs2cs    +proj=stere +lat_0=52.15616055555555 +lon_0=5.38763888888889
+k=0.999908
> +x_0=155000 +y_0=463000 +ellps=bessel +units=m +towgs=565.04,49.91,465.84,-0.409394387,0.35970519561,-1.868491 +no_defs  +to +proj=utm +zone=31 +datum=wgs84 


If gdalwarp isn't agreeing with the result of the cs2cs then we can talk
about that.  If you think the cs2cs result is wrong, then that is another
ball of wax. 

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent