[mapserver-users] Automatic simplification based on resolution

[Eichner, Andreas - SID-NLKM]

Wasn't RFC 86 (http://mapserver.org/development/rfc/ms-rfc-86.html) intended to solve such problems? Does something like the following work and do the job?

  SCALETOKEN
    NAME "%geometry%"
    VALUES
      "0" "the_geom"
      "1000" "st_simplify(the_geom, 100)"
      "10000" "st_simplify(the_geom, 1000)"
    END
  END
  DATA "the_geom from (select %geometry% as the_geom, prop1 from roads) as foo"

Would be nice to know if that would work...

Regards,
Andreas Eichner

> -----Ursprüngliche Nachricht-----
> Von: mapserver-users-bounces at lists.osgeo.org [mailto:mapserver-users-
> bounces at lists.osgeo.org] Im Auftrag von thomas bonfort
> Gesendet: Dienstag, 31. Dezember 2013 18:46
> An: Rahkonen Jukka
> Cc: Mapserver-Users (mapserver-users at lists.osgeo.org)
> Betreff: Re: [mapserver-users] Automatic simplification based on
> resolution
> 
> Jukka,
> IIRC this has already surfaced a few times on the mailing list or the
> bugtracker. MapServer already simplifies geometries at the pixel
> level
> before sending them to the renderers, and from my testing at the time
> was more efficient at doing so than using st_simplify(), with the
> added bonus that the cellsize (resolution, units per pixel) does not
> need to be factored in the actual SQL query, and that the
> simplification applies to all data backends.
> Doing the simplification inside postgis does however make sense if
> the
> data transfer from db to mapserver is a bottleneck, and/or
> potentially
> if reprojection is involved (as less points would need to be fed into
> proj). If you can come up with hard numbers to show there is a gain
> I'd be interested.
> 
> regards,
> thomas
> 
> 
> 
> On 31 December 2013 10:31, Rahkonen Jukka <jukka.rahkonen at mmmtike.fi>
> wrote:
> > Hi,
> >
> > Mapnik has such a feature
> http://blog.cartodb.com/post/20163722809/speeding-up-tiles-rendering
> > Andrea Aime is experimenting with it with Geoserver and is reaching
> a 50% speedup.
> > http://osgeo-org.1560.x6.nabble.com/Some-interesting-optmizations-
> from-Jonathan-s-load-test-td5095839.html
> > Can Mapserver do the same?
> >
> > -Jukka Rahkonen-
> > _______________________________________________
> > mapserver-users mailing list
> > mapserver-users at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/mapserver-users
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