Paket: proj-rdnap (2008-8) [non-free]

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:

 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.

Märken: Field: Geography, Role: Application Data

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