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

Tue Feb 23 10:22:36 PST 2021

Hi,

Not sure if/how I can help on this benchmark.
If I understand well you want to know if disabling the simplification on
the marker line symbol layer only would make a huge difference or not on
rendering performance. But as far as I saw the option is only available for
the whole layer at the moment.

Jérémie.

Le ven. 19 févr. 2021 à 22:25, Nyall Dawson <nyall.dawson at gmail.com> a
écrit :

> 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.
> > > _______________________________________________
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