| PackageDescription | RDNAP grid correction files for PROJ
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
developed 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:
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1) The rdtrans2008 NTv2-grid can only give identical results to
RDNAPTRANS™2008 within 1 millimeter at ground level onshore and at
mean sea level offshore. The horizontal deviation is approximately
1 millimeter per 50 meter height difference from ground level or mean
sea level.
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.
.
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
result. |