[QGIS-Developer] Non-cartesian buffering

[Nyall Dawson]

On Thu, 25 May 2023 at 10:27, Alexis R.L. via QGIS-Developer
<qgis-developer at lists.osgeo.org> wrote:
>
> Greetings,
>
> I was looking into buffers and noticed that arc could do geoid buffering but it's not something qgis could do yet.
>
> Now I'm going to assume that such a thing would usually need to be implemented in geos and in one of the ticket asking about this, another repository was pointed to ( https://github.com/libgeos/geos/issues/820).
>
> That repository being https://github.com/google/s2geometry now I don't know how important generating things based on non-cartesian distance is and if such tools are to be made if they should be made in QGIS instead of relying on external libs.

Unfortunately S2 isn't a sufficiently generic approach in my opinion.
It is designed completely around a spherical earth assumption, so
doesn't work for situations where an ellipsoidal model is required
(and definitely doesn't work for non-earth bodies).

What we need is a library which can perform geographic buffering using
an ellipsoid. Which doesn't exist yet, but
https://geographiclib.sourceforge.io/ would be a good place for this
to exist...

Nyall




>
> As more and more global and 3D things are added,I assume that those will be more important.
>
> Thanks,
>
> Alex
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