How does Survex translate between GPS and UK grid?

[Tarquin Wilton-Jones]

Hi Olly,

(* slaps fingers and corrects spelling, sorry *)

> https://www.ordnancesurvey.co.uk/business-government/tools-support/os-net/for-developers
> says "This software is licensed as per the terms of the BSD Licence"

Well, that's positive.

> (with a link to the 2-Clause BSD Licence).  It seems that includes the
> models as well from a quick poke inside a download

Yes, main file is 40 MB uncompressed, 11 MB compressed. That would be
hefty even if you were to bundle it in compressed form.

A separate download would be a possibility, but even then, it's
something proj would need on most systems, rather than Survex itself.
But it would need bundling (or installing as a separate package?) for
Windows.

https://github.com/OSGeo/proj-datumgrid/issues/21 and
https://github.com/OSGeo/PROJ-data/tree/master/uk_os seem to contain it,
for different versions of proj (I can't tell which one you are using
here on Windows). The main UK files are these, and I note that the size
is much smaller; about 2 MB:
https://github.com/OSGeo/PROJ-data/tree/master/uk_os

I am assuming that I cannot just take those files and dump them in the
proj directory.

Cheers,

Tarquin