[Geoserver-devel] About Filters in sld files

Hi to all,

   I have a query, that in some of the sld files filters are used.
  
   I need to know what is the purpose of the filters in sld files.
   I'm using Geroserver 1.4 and in that there are no filters used anywhere.
   In which version of the Geoserver the filters used. How does it helps in
Geoserver performance.

Thanks in advance.

Raj
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Bobby ha scritto:

Hi to all,

   I have a query, that in some of the sld files filters are used.
     I need to know what is the purpose of the filters in sld files.
   I'm using Geroserver 1.4 and in that there are no filters used anywhere. In which version of the Geoserver the filters used. How does it helps in
Geoserver performance.

This is a question for the users mailing list, however...

In the user guide (http://docs.codehaus.org/display/GEOSDOC/User) we have two chapter about SLD: http://docs.codehaus.org/display/GEOSDOC/1.3+Style+Your+Map
and
http://docs.codehaus.org/display/GEOSDOC/OGC+SLD+Explanations+and+Samples

Plus, there are the SLD and Filter OGC specifications you may read.

About performance, I don't know wheter filters can help. Filters are
there to make you draw certain features with certain styles.
You can use them to increase performance if, for example, at a
certain zoom level you want to show only a subset of features, for
example, on a road network, show only major roads when zoomed out,
and make other kind of roads visible as you zoom in more.
This can be achieved by creating multiple rules, each one catching
a specific road type, with filters.

Hope this helps
Cheers
Andrea