[Qgis-user] Unexpected comparison Web-Mercator vs Mercator

[Javier Jimenez Shaw]

I created an issue in github
https://github.com/qgis/QGIS/issues/62654

phidrho <https://github.com/phidrho> answered something that "solves" the
problem: deselect "Clip features to canvas extent"
https://download.qgis.org/qgisdata/QGIS-Documentation-3.10/live/html/en/docs/user_manual/style_library/symbol_selector.html#:~:text=Clip%20features%20to%20canvas%20extent

I don't understand very well that this option is doing, but apparently
impacts how geometries are reprojected in some cases.

Thanks

On Wed, 23 Jul 2025 at 17:34, Greg Troxel via QGIS-User <
qgis-user at lists.osgeo.org> wrote:

> Vedran Stojnović via QGIS-User <qgis-user at lists.osgeo.org> writes:
>
> > QGIS should do on-the-fly reprojection, but you can count on only the
> > defined vertices of geometry as far as I know.
>
> Do you mean:
>
>   The meaning of a linestring is the points at vertices, and between
>   them, a straight line in whatever CRS the data is currently expressed
>   in?
>
> and that the points are transformed, and then the straight line between
> is straight in the sense of the target CRS?
>
> I think that's what Javier is trying to do: to take a line with two points
> in
> EPSG:3395, and a line *that is straight in 3395* with three points, and
> transform it all to 3857.
>
> That should result in a line (layer 2d) that is straight in 3857, and
> then two lines, each straight in 3857, that are from lower-left to
> middle and middle to upper-right, with each transformed.
>
> > You can execute "Densify by interval" or "Densify by count" on source
> > geometries in source CRS - you can use the "Edit features in place"
> option.
> > This will convert your "line" to "linestring" with many smaller segments.
> > Please check if this solves your problem?
> >
> > I remember that there was an announcement for some QGIS 3.x version that
> > this "densification" of vertices is done automatically, but maybe it
> > stopped working or works for only certain source CRSs (maybe the ones
> > defined in Lat-Long) - it seems that it works for "Identify tool".
>
> Are you suggesting that when qgis transforms a linestring, it is doing
> some kind of densification to show a line in the target CRS which is the
> transform of e.g. the source-CRS line that fits in the canvas?
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