[Proj] Datum shifts in PROJ's EPSG table (The Netherlands and Belgium)

[Frank Warmerdam]

Roger Oberholtzer wrote:
> If I use a 'from' of "+proj=latlong +ellps=WGS84", I get incorrect
> values. This was my original settings, but my users are complaining that
> the derived values are off by 65 meters from what was expected. The
> expected values are being provided by the Dutch road authority.

Roger,

Please use +datum=WGS84.  This internally expands to:
    +ellps=WGS84 +towgs84=0,0,0

I'm not sure if it makes a difference, but doing it your way is making
my skin crawl!

> The 'from' string is describing my source data, right? If so, I think
> the problem then is the 'to' specification.
> 
> There has been a discussion on this list about RD. I am not convinced
> that the conclusions were fully correct. Or at least not universal in
> the Netherlands.
> 
> I really feel I am going in circles here. I am looking for the most
> efficient way to convert WGS 84 lat/longs into RD (Dutch) eastings and
> northings. I think part of the problem is that proj is so flexible.
> Determining the best way, as opposed to just one that will work, eludes
> me.

I can't vouch for the +towgs84 parameters.  I feel your pain, but I'm
not sure I can help.

Best regards,
-- 
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