Hi,
I wonder if there is a 'group by'-style filter in SLD?
What I'd like to do is to create a union of a number of inter-related
geometries, and render the union of them. one way to go at it would be
to be able to group the geometries by one of their properties, which
would have the same value for the geometries in the same group. then I
could apply a union function on such a group of geometries.
Is there something similar available in SLD?
Best regards,
Akos
Akos,
Check out the transformation functions that you can use in the SLD: http://docs.geoserver.org/stable/en/user/styling/sld-tipstricks/transformation-func.html, particularly ‘Categorise’. This way, geometries that have the same property are rendered using the same visualisation. That’s at least part of an answer. Not sure about the geometry unioning, though…
Kind regards,
Edward
Date: Sun, 25 Nov 2012 12:06:42 +0100
From: akos@anonymised.com7…
To: geoserver-users@lists.sourceforge.net
Subject: [Geoserver-users] group by- style filter in SLD?Hi,
I wonder if there is a ‘group by’-style filter in SLD?
What I’d like to do is to create a union of a number of inter-related
geometries, and render the union of them. one way to go at it would be
to be able to group the geometries by one of their properties, which
would have the same value for the geometries in the same group. then I
could apply a union function on such a group of geometries.Is there something similar available in SLD?
Best regards,
Akos
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On Sun, Nov 25, 2012 at 12:06 PM, Ákos Maróy <akos@anonymised.com> wrote:
Hi,
I wonder if there is a ‘group by’-style filter in SLD?
What I’d like to do is to create a union of a number of inter-related
geometries, and render the union of them. one way to go at it would be
to be able to group the geometries by one of their properties, which
would have the same value for the geometries in the same group. then I
could apply a union function on such a group of geometries.Is there something similar available in SLD?
Nope, standard SLD does not allow anything like real geometry unioning.
What Edward suggested works if all you want to do is filling the geometries
with the same color, without drawing an outline and labeling them.
Going out of the standard it’s technically feasible to perform union-ing on the
fly using a rendering transformation, but we don’t have a “Dissolve” process
right now (and writing one that is not fully memory bound but still provides
rendering worth performance is not trivial either, we’d need some sort
of smart caching).
Anyways, the rendering transformation topic is covered here:
http://docs.geoserver.org/latest/en/user/styling/sld-extensions/rendering-transform.html
Cheers
Andrea
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Can you provide a bit more detail about the visual effect you are hoping to achieve by unioning? That would help in determining what the possible alternatives might be.
If your datasource supports it you might be able to do this in a SQLView (e.g. in PostGIS using ST_Union).
On Sun, Nov 25, 2012 at 3:06 AM, Ákos Maróy <akos@anonymised.com> wrote:
Hi,
I wonder if there is a ‘group by’-style filter in SLD?
What I’d like to do is to create a union of a number of inter-related
geometries, and render the union of them. one way to go at it would be
to be able to group the geometries by one of their properties, which
would have the same value for the geometries in the same group. then I
could apply a union function on such a group of geometries.Is there something similar available in SLD?
Best regards,
Akos
Monitor your physical, virtual and cloud infrastructure from a single
web console. Get in-depth insight into apps, servers, databases, vmware,
SAP, cloud infrastructure, etc. Download 30-day Free Trial.
Pricing starts from $795 for 25 servers or applications!
http://p.sf.net/sfu/zoho_dev2dev_nov
Geoserver-users mailing list
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–
Martin Davis
OpenGeo - http://opengeo.org
Expert service straight from the developers.
sure you can see here: look at the a shape that is made up of a rectangle and a circle. in reality, this is a single entity, and should be joined and rendered as a single entity. the union of the rectangle and the circle is the real body to render. hm, interesting…
On 26/11/12 18:54, Martin Davis wrote:
Can you provide a bit more detail about the visual effect you are hoping to achieve by unioning? That would help in determining what the possible alternatives might be.
If your datasource supports it you might be able to do this in a SQLView (e.g. in PostGIS using ST_Union).