[PROJ] Using +nadgrids with cs2cs (version 4.9.3)

[Chris Crook]

Hi

I am trying to configure a cs2cs command line to use the New Zealand NTv2 grid to convert from NZGD49 to NZGD2000.
I have tried several variants of the command below, but so far none have resulted in the output coordinates being different
from the input coordinates?

Please can anyone offer suggestions as to what would work?

echo '173 -41 0' | cs2cs -v -f %.10f +proj=latlong +ellps=GRS80 +to +proj=latlong +datum=nzgd49  +nadgrids=nzgd2kgrid0005.gdb
# ---- From Coordinate System ----
#Lat/long (Geodetic alias)
#
# +proj=latlong +ellps=GRS80
# ---- To Coordinate System ----
#Lat/long (Geodetic alias)
#
# +proj=latlong +datum=nzgd49 +nadgrids=nzgd2kgrid0005.gdb +ellps=intl
#--- following specified but NOT used
# +towgs84=59.47,-5.04,187.44,0.47,-0.1,1.024,-4.5993
173.0000000000  -41.0000000000 0.0000000000


Thanks
Chris

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