[PROJ] Vertical Transformations?

[Greg Troxel]

Even Rouault <even.rouault at spatialys.com> writes:

> With the vertconc.gtx grid available, you'll get
>
> $ echo "45 -100 100" | cs2cs -f "%.8f" EPSG:7406 EPSG:5500 
> 44.99998071	-100.00039555 30.85853056
>
> Without it, you'll get just us-ft to metre for the vertical part:
> 44.99998071	-100.00039555 30.48006096

With the grids being in separate distribution files, it seems easy to
end up with them not installed.

I wonder if transformations that need grid files for correct behavior
should fail rather than skip the transformation, at least by default.