[Qgis-user] Best practice when using UK national grid and GPS

[Jim Jackson]

Thanks to Greg amd Saber. 

On Mon, 4 May 2026, Saber Razmjooei wrote:

> Hi Jim,
> 
> Here is a full article on how projections (specifically the British
> National Grid) work in QGIS and what you can do to improve your data
> collection when using on-the-fly transformation:
> https://merginmaps.com/docs/gis/projections/#projections
> 
> Kind regards
> Saber
> 
> 
> On Fri, 1 May 2026 at 19:36, Jim Jackson via QGIS-User <
> qgis-user at lists.osgeo.org> wrote:
> 
> >
> >
> > QGIS version  3.40.6-Bratislava
> > QGIS code branch Release 3.40
> > OS Linux Devuan GNU/Linux 6 (excalibur) (basically Debian Trixie)
> >
> > Hi All,
> >
> > As a member of a community Archaeology Group, I'm using QGIS for recording
> > archaeological features in the UK. I'm using Google Satellite,
> > OpenStreetMap and National Library of Scotland historic basemaps, which
> > (as
> > I understand it) use EPSG:3857.
> >
> > I have an RTK GPS receiver for collecting data points which are in
> > EPSG:4326.
> > I
> > also get UK National Grid data points from a colleague who has access to a
> > total station.
> >
> > As I think I understand it, I need to set the project CRS to UK national
> > grid EPSG:27700 to get sensible distance measurements However I then get
> > occasional warnings "Used a ballpark transform from EPSG:27700 to
> > EPSG:3857" indicated less than accurate transformations, and then I get
> > lost!!!!
> >
> > Can anyone point me to a tutorial on how to set up QGIS in the UK to get
> > accurate transformations in these circumstances (which can't be that
> > unusual).
> >
> > Any advice and/or pointers where I've gone wrong gratefully received.
> >
> > Jim Jackson
> >
> >
> > _______________________________________________
> > QGIS-User mailing list
> > QGIS-User at lists.osgeo.org
> > List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> > Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> >
> 
> 
> -- 
> 
> Saber Razmjooei
> 
> Co-Founder
> 
> lutraconsulting.co.uk
> 
>  [image: https://www.linkedin.com/in/saber-razmjooei/]
> <https://www.linkedin.com/in/saber-razmjooei/>
> <https://www.youtube.com/@LutraConsulting>
> <https://github.com/lutraconsulting>
> 
> <https://www.lutraconsulting.co.uk/>
>