Pietro
Hi, I have been tricking around with Zoom Level based Styling for
OpenStreetMap (Just Ireland) on GeoServer. We utilise a PostGIS database
back end to store the features, a SLD with different zoom levels is then
used to display the features required at each level. If you want, I can
send a sample in text format to you to look at if you would like?
A similar QGIS Style could be created to do the same thing, using rule
based styling.
Other than that, I believe there is no way to do what you want other
than the way you suggested yourself, with the different table for each
zoom level.
I am open to correction on this, but some simplification of the
geometry, happens anyway, for all geometry outside of the bounding box
that is your canvas does it not?
Sorry I cant be of more help.
Regards,
Richard.
On 18/02/2016 13:05, Pietro Rossin wrote:
Hello qgis users
I hope this is the right place to ask for help in selecting the right
strategy to spped up the data served by qgis-server/lizmap
I have many polygonal features that can be seen at various zoom level
I want to serve them as a webis with qgis-server and Lizmap
Data are on a postgis server with all indexes set.
I had some suggestion to simplify the geometry let's say with 3-4
simplyfication level on the nodes of any polygon.
So I made 3 geometry column (orig - simpl1, simpl2 ecc) all the same kind of
the original one and each field with its index.
In simpl1, 2 3 ecc I calculate a simplification with
ST_SimplifyPreserveTopology(geometry , float) with increasing tolerance
based on original geometry.
Now I will like to use these geometry columns to load simpler features at
low zoom and richer ones at higher zoom level.
Is it possible to tell qgis to load a particular geometry column based on
the zoom level?
This thing should be also available in qgis-server and then in lizmap..
One solution I found was to make different view/query to load layers with
the desired geometry column and use visibility based on scale to show/hide
different layers..
Any other way?
Is it preferable to create views in Postgis or to query data by qgis db
manager?
Thanks for your help
Pietro
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*_Richard McDonnell_*
*GIS Specialist PgD GIS AssocSCSI*
*OPW FRM Data Management*
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