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<pre wrap="">Pietro</pre>
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?<br>
A similar QGIS Style could be created to do the same thing, using
rule based styling.<br>
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.<br>
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?<br>
Sorry I cant be of more help.<br>
Regards,<br>
<br>
Richard.<br>
<br>
<br>
<div class="moz-cite-prefix">On 18/02/2016 13:05, Pietro Rossin
wrote:<br>
</div>
<blockquote cite="mid:1455800746790-5251409.post@n6.nabble.com"
type="cite">
<pre wrap="">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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<div class="moz-signature">-- <br>
<b><u>Richard McDonnell</u></b><br>
<b><small><small><small>GIS Specialist PgD GIS AssocSCSI</small></small></small></b><br>
<b><small>OPW FRM Data Management</small></b><br>
<b><small>52 Stephens Green, Dublin 2.</small></b><br>
<small><small>TEL: 01 6476543</small></small></div>
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