Owner: Bas Couwenberg <sebas...@xs4all.nl>
* Package name : proj-rdnap
Version : 2008
Upstream Author : RDNAP
* URL :
* License : RDNAPTRANS2008-NTv2
Programming Lang: N/A
Description : RDNAP grid correction files for PROJ.4
Kadaster and Rijkswaterstaat CIV, working together under the name RDNAP,
developed RDNAPTRANS™2008, the precise and official transformation
between ETRS89 and the dutch national horizontal and vertical coordinate
reference systems the Stelsel van de Rijksdriehoeksmeting (RD) and the
Normaal Amsterdams Peil (NAP). A ‘simplified’ procedure has been
devolped which uses a NTv2-grid for the transformation between ETRS89
and RD as well as a VDatum-grid for the transformation between ETRS89
and NAP. This ‘simplified’ procedure has the following limitations:
1) The rdtrans2008 NTv2-grid can only give identical results to
RDNAPTRANS™2008 within 1 millimeter at ground level onshore and at
mean seal level offshore. The horizontal deviation is approximately
1 millimeter per 50 meter height difference from ground level or mean
2) An exception to 1) is the border of the RDNAPTRANS™2008 correction
grid. Transformation results within cells of the rdtrans2008 NTv2-grid
that are intersected by the border of the RDNAPTRANS™2008 correction
grid can result in deviations of up to 20 centimeter.
3) The naptrans2008 VDatum-grid cannot be used to determine deflections
of the vertical. For this the NLGEO2004 geoid model has to be used.
4) The naptrans2008 VDatum-grid is referenced to the Bessel-1841 ellipsoid
and cannot be used stand-alone, it has to be used in combination with
the rdtrans2008 NTv2-grid.
Taking into account the limitations listed above, the rdtrans2008 NTv2-grid
and naptrans2008 VDatum-grid can be used as an alternative to
RDNAPTRANS™2008 to transform geographic ETRS89-coordinates to
projected RD-coordinates with grid correction applied and NAP-heights.
The figure in appendix 1 shows the precise and official RDNAPTRANS™2008
flow-chart on the left and on the right the flow-chart for the ‘simplified’
Note that, although the resulting RD/NAP and ETRS89 coordinates from the
transformation will be correct, geographic Bessel-1841 coordinates will
differ in both procedures and should only be considered as an intermediate
The package will be maintained within the Debian GIS team.
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