[PROJ] Question about new grid file in Czech Rep.

[Javier Jimenez Shaw]

Hi

Playing with the latest master in the Czech Republic, I noticed something
strange.
The new grid file cz_cuzk_table_-y-x_3_v1710.tif is used only if the
projected CRS EPSG:5514 is used, but not with its geographic
"parent", S-JTSK EPSG:4156. Well, it is at position 13 on the list of
operations.

Just compare
PROJ_NETWORK=ON ./projinfo -o proj --3d EPSG:4258 EPSG:5514+8357
--spatial-test intersects

with

PROJ_NETWORK=ON ./projinfo -o proj --3d EPSG:4258 EPSG:4156+8357
--spatial-test intersects

Doing only 2D transformation, it is even more clear. The grid file is never
used with EPSG:4156

Does it make sense?

I know that the grid file is defined in EPSG:5514. But I assume that the
correction applies to the geographic system transformation, not to the
Krovak projection itself.

Cheers
Javier.
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