[gdal-dev] Datum shiftings

[Juan Pedro Pérez Alcántara]

Hi there,

after spending a lot of time with gdaltransform, I'm at a loss trying to
figure out how to make a datum shifting using a NTv2 grid.

First, I'm not sure if GDAL use my PROJ4 installation to perform the
shifting. My PostGIS certainly does, as well as other software that relies
on PROJ. I've modified the CRS definitions that needs to use the grid on
the PROJ4 share data and that's all for those programs.

But I guess if GDAL uses its own methods to transform. I've been messing
with the pcs and gcs files, with the PROJ definitions in .wkt files, and
trying to incorporate my own WKT, but to no avail.

My questions are:

Does GDAL make use of the PROJ in my system? It seems to me that no.

How can I make GDAL to use a NTv2 grid to shift between some datums?

Thanks so much in advance,
Juan Pedro Pérez Alcántara
Technical Director
jp.alcantara at geographica.gs <alberto.asuero at geographica.gs>
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