[Qgis-user] Symbol lines every km, moving when changing scale or moving map

[Nyall Dawson]

On Fri, 19 Feb 2021 at 23:00, Andreas Neumann <a.neumann at carto.net> wrote:
>
> Hi Jérémie,
>
> Ah good to hear!
>
> I'm not a big fan of this fact that line simplification is turned on by default in QGIS. I believe that users should consciously turn it on if they want it!

I'd be interested to see some benchmarks of disabling vs enabling
simplification for the marker line symbol layer alone. If it's not too
expensive, we could skip it automatically for line marker symbol
layers (it makes a HUGE difference to the rendering speed for simple
line layers and other symbol layer types, but the intention is that
the results should be visually identical to no simplification).

Nyall

>
> Your example shows that it can lead to confusion (understandably).
>
> Good that it works now. Note that you can override this setting on a per layer base in the layer properties - so not all layers need to have the same setting.
>
> Greetings,
>
> Andreas
>
> On 2021-02-19 13:40, Prud'homme Jérémie wrote:
>
> Hi,
>
> I had simplification turned on, indeed...
>
> I deactivated it :
> - in the Options as you mention, so that it is deactivated for newly added layers
> - in my layer options (Rendering properties)
>
> And it is ok now.
>
> It makes sense that if the line is simplified the distance vary !
>
> Thanks Andreas.
>
>
> Jérémie.
>
> Le ven. 19 févr. 2021 à 11:12, Andreas Neumann <a.neumann at carto.net> a écrit :
>
> Hi Jérémie,
>
> Do you have geometry simplification turned off? See "Settings" --> "Options" --> "Rendering" --> "Enable feature simplification ..."
>
> Make sure this is deactivated (I think it is enabled by default).
>
> Greetings,
>
> Andreas
>
>
> On 2021-02-19 11:05, Prud'homme Jérémie wrote:
>
> Tested too fast :(
>
> Behavior is ok when zooming in, but still problems when zooming out (whereas the entire feature is visible !).
> See here : https://www.zupimages.net/viewer.php?id=21/07/ehlo.gif
>
> Circles should follow the strokes generated with the tool "Points along geometry".
>
>
> Jérémie.
>
> Le ven. 19 févr. 2021 à 10:03, Prud'homme Jérémie <p.jeremie at gmail.com> a écrit :
>
> Hi,
>
> Thank you very much Nyall, this one was pretty well hidden.
>
> With clipping unchecked, behavior is as expected for my use case.
>
>
> Jérémie.
>
> Le jeu. 18 févr. 2021 à 23:29, Nyall Dawson <nyall.dawson at gmail.com> a écrit :
>
> On Wed, 13 Jan 2021 at 06:33, Prud'homme Jérémie <p.jeremie at gmail.com> wrote:
> >
> > Hi,
> >
> > I'm using QGIS 3.10.
> >
> > I tried to use only symbology to display a stroke every km along a road.
> > The project CRS is 2154 (Lambert 93).
> >
> > When adding a ""symbol line" with an interval of 1000 map units (meter for 2154) – or 1000 meters at scale, same result – I achieve to display symbols every km.
> >
> > Problem is when I move the map or change scale, the symbols do not always stay in place. They are sometimes misplaced.
> >
> > I've been told that problem can be that the first node of the line is not always the reference to calculate the intervals.
>
> From the bottom of the symbol widget, click the "Advanced" button and
> uncheck "Clip features to canvas extent".
>
> Nyall
>
>
>
> >
> > You can find a GIF here that displays my problem : https://zupimages.net/viewer.php?id=21/02/nvr2.gif
> >
> > Circles are symbols via Symbology.
> > Strokes are symbos on points generated vith the tool "Points along geometry".
> >
> > You can see that circles are not always at the same place as the strokes.
> >
> > Is it a "normal" behavior ?
> > Anyway as a user I would expect that symbols are always generated at the same place from the starting node.
> >
> > Thanks for your enlightments on this.
> >
> > Jérémie.
> > _______________________________________________
> > 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
>
>
> _______________________________________________
> 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
>
>
>
> _______________________________________________
> 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