[Proj] EPSG:28992 to EPSG:23031 conversion

[Bart van den Eijnden (OSGIS)]

Hi Jean-Claude,

I am using PROJ 4.4.9 so that should not be necessary or am I mistaken?

Best regards,
Bart

Jean-Claude Repetto wrote:
> 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
>
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>


-- 
Bart van den Eijnden
OSGIS, Open Source GIS
bartvde at osgis.nl
http://www.osgis.nl