[Qgis-developer] Removing old labelling / polygons / WMS & tiles

[Mayeul Kauffmann]

Thanks Andreas!
You are right. Still there are 3 different issues with labeling and
tiling:
-No placement outside the BBOX
-Dynamic label placement
-Repeated labels

Larger area (meta buffer) solves only the first issue, the 2nd and 3rd
need work on the WMS side (hence either old labelling or the solution
you mentioned).
This is explained very well in images here:
http://mapproxy.org/docs/latest/labeling.html

I still need a few days to finish uploading my 6 GB of QGIS-Mapproxy
tiles illustrating this! Stay tuned...

Mayeul


Le vendredi 09 mars 2012 à 09:17 +0100, Andreas Neumann a écrit :
> Hi Mayeul,
> 
>  I find it useful that clipped features at the edge of the map always 
>  get labeled. I actually demanded such a feature from labeling 2.0
> 
>  If you want to generate fixed tiles I  think the way to go is by 
>  clipping a much larger area and then clip out the center. Proxies, such 
>  as  mapproxy can generate these tiles. That way you get good performance 
>  and the advanced labeling of QGIS.
> 
>  If you want fixed labels in QGIS you can generate the centroids by some 
>  tool (e.g. Postgis SQL) and set the x and y columns. That way you get 
>  guaranteed fixed labels.
> 
>  But I am not a tiling expert - so I may be wrong.
> 
>  Andreas
> 
>  On Thu, 08 Mar 2012 23:22:22 +0100, Mayeul Kauffmann wrote:
> > I also experienced problems with new labelling for polygons.
> > Even when you set new labelling to try only one position, and stay on
> > centroid, labels still move when you pan. They kind of stay on the
> > centroid of the *visible* part of the area.
> > It is annoying when generating tiles with qgis server: you can get
> > duplicated or cut labels.
> > Users have difficulty with this and sometimes the only option is the 
> > old
> > labelling.
> >
> > (Cannot find back that wonderful post of a frequent qgis blogger who
> > faced the issue and went back to UMN Mapserver. SUre s/he is reading
> > this)
> > Other example:
> > 
> > http://osgeo-org.1560.n6.nabble.com/QGIS-Server-street-names-in-tiles-td4540846.html
> >
> >
> > Blind guess: Maybe the fact that it recalculates centroid of partial
> > polygons at each refresh can cast some light on the performance 
> > issue?
> >
> > Mayeul
> >
> > Le mardi 06 mars 2012 à 14:00 +0100, Andreas Neumann a écrit :
> >> Hi,
> >>
> >>  Please be more concrete - there are almost 100 different settings 
> >> and
> >>  combinations. What is the problem very precise/concrete.
> >>
> >>  What settings did you use, what geometry type - maybe accompanied 
> >> with
> >>  screenshots of your settings.
> >>
> >>  In my experience the new labeling works very well and fast. Only 
> >> area
> >>  geometries are slow to label. Martin Dobias is currently working on
> >>  improving/accelerating the labeling of area geometries.
> >>
> >>  Andreas
> >>
> >>
> >>  On Tue, 06 Mar 2012 13:13:11 +0100, Paolo Cavallini wrote:
> >> > Il 05/03/2012 17:06, Andreas Neumann ha scritto:
> >> >> Hi,
> >> >>
> >> >> We discussed this issue backwards and forwards and it would be 
> >> good
> >> >> to make some progress here. There is really not a lot missing in 
> >> the
> >> >> new labeling and I don't agree with Paolo that the new labeling 
> >> is
> >> >> slower than the old labeling. It may have different settings and 
> >> thus
> >> >> people are comparing apples with oranges.
> >> > Please test it with an old PC, ora netbooK: in our case it is 
> >> almost
> >> > unusable with <300 polygons.
> >> > Also, some of the bugs are pretty serious.
> >> > All the best.
> >>
>