Hi,
checking the code, there are two cases in which ST_Simplify is not called:
- If the column is geography instead of geometry (I guess at the time of
writing st_simplify did not work against geography, not sure if it does
today)
- If the column type contains curved geometries, which ST_Simplify
cannot handle, at least in the version of postgis that I tested (throws an
error). I believe the ticket I opened at postgis to get a function telling
me if st_simplify would work got recently closed, they decided not to fix
it that way, but to linearize geometries before st_simplify instead.
However, not sure if the linearization already happened, and starting with
which version of postgis
Jason, are you falling in any of these cases?
Cheers
Andrea
On Tue, Sep 5, 2017 at 4:50 PM, Rahkonen Jukka (MML) <
[email protected]> wrote:
> Hi,
>
>
>
> I copied the states shapefile into PostGIS and had a try with GeoServer
> 2.11. GetMap with a WMS client generates SQL queries like this:
>
>
>
> 05 syyskuuta 17:46:07 DEBUG [org.geotools.jdbc] - SELECT
> "gid",encode(ST_AsBinary(ST_Simplify(ST_Force2D("geom"),
> 0.05529411764705401)),'base64') as "geom" FROM
>
> "public"."states" WHERE ("geom" && ST_GeomFromText('POLYGON
> ((212.626470588235
>
> 3 22.861764705882347, 212.6264705882353 70.13823529411765,
> 301.3735294117647 70.
>
> 13823529411765, 301.3735294117647 22.861764705882347, 212.6264705882353
> 22.86176
>
> 4705882347 <(470)%20588-2347>))', 4326) OR "geom" &&
> ST_GeomFromText('POLYGON ((-147.3735294117647
>
> 22.861764705882347, -147.3735294117647 70.13823529411765,
> -58.62647058823529 70.
>
> 13823529411765, -58.62647058823529 22.861764705882347, -147.3735294117647
> 22.861
>
> 764705882347))', 4326))
>
>
>
> So Geoserver does add ST_Simplify for me. I can’t understand why it does
> not do that for you.
>
>
>
> -Jukka Rahkonen-
>
>
>
> *Lähettäjä:* Jason Newmoyer [mailto:[email protected]]
> *Lähetetty:* 5. syyskuuta 2017 17:10
> *Vastaanottaja:* GeoServer Mailing List List <geoserver-users@lists.
> sourceforge.net>
> *Aihe:* [Geoserver-users] Using simplify function in SLD
>
>
>
> My idea was to use simplify as a geometry transformation in my SLD to
> improve performance at certain scales where OSM data is just too heavy and
> all the normal tricks for performance just don't cut it.
>
>
>
> Reading the function reference
> <http://docs.geoserver.org/latest/en/user/filter/function_reference.html#filter-function-reference>
> it says: "If a function is described in the Capabilities document but is
> not in this reference, then it might mean that the function cannot be used
> for filtering, or that it is new and has not been documented. Ask for
> details on the user mailing list."
>
>
>
> How is the "approved" function list controlled? Is there a way to change
> it by configuration?
>
>
>
> By the way I'm using PostGIS with "on the fly simplification" enabled but
> still the queries do NOT use ST_Simplify. It seems like this would be a
> better solution. Where can I learn more about how this feature works?
>
>
> Thanks,
> Jason
>
>
>
>
> Jason Newmoyer
> Newmoyer Geospatial Solutions
>
> 843.606.0424 <(843)%20606-0424>
>
> [email protected]
>
>
>
>
>
>
>
> ------------------------------------------------------------
> ------------------
> Check out the vibrant tech community on one of the world's most
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> Geoserver-users mailing list
>
> Please make sure you read the following two resources before posting to
> this list:
> - Earning your support instead of buying it, but Ian Turton:
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>
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>
>
--
Regards,
Andrea Aime
==
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==
Ing. Andrea Aime
@geowolf
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