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

[Oscar van Vlijmen]

> From: Roger Oberholtzer
> Date: Thu, 02 Nov 2006 20:54:27 +0100
> Subject: Re: [Proj] Datum shifts in PROJ's EPSG table (The Netherlands and
> Belgium)

.....

> 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.

If you could provide a clear numerical example with enough significant
digits of what is expected, then there is some hope someone will be able to
give some clues.

See also the good advise from:
> From: Greg Troxel
> Date: Thu, 02 Nov 2006 15:55:23 -0500
> Subject: Re: [Proj] Datum shifts in PROJ's EPSG table (The Netherlands and
> Belgium)

...

> 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.

The RDNAPTRANS (Windoze) program from the Dutch Cadastre seems to be the one
and only 'universal' NL solution.
Note that this program does a grid interpolation, which complicates the
matter if you are trying to resolve datum transformation and projection
issues.

Note that there is also an 'independent' polynomial solution for the direct
conversion from wgs84 lat,lon to RD x,y, with a stated accuracy of about 25
cm. I forgot with respect to what (mathematical double stereographic
projection or the grid interpolated projection).
Ref:
"Benaderingsformules voor de transformatie tussen RD- en
WGS84-kaartcoördinaten".
http://www.dekoepel.nl/pdf/Transformatieformules.pdf