Note that I don't know the correct syntax, but functionally, I would expect this to work...
Difference(geom, Buffer(geom, -something)) P. On Tue, Feb 28, 2012 at 10:06 PM, Robert Buckley <robertdbuck...@yahoo.com> wrote: > Thanks for that...shame it didn´t work. > > I have already looked at negative buffers, but they create a polygon within > a polygon and not a hole within a "negative-buffered" polyon. i.e my polygon > needs to be transparent in the center past the negative buffer so underlying > features can be seen. > > Andrea Aime thought it could be done with the "Difference" SLD filter, but I > can´t seem to get it to work due to my lack of understanding of how the > filter works. > > http://docs.geoserver.org/latest/en/user/styling/sld-reference/filters.html > > yours, > > Rob > > > > > > ________________________________ > Von: Paul Ramsey <pram...@opengeo.org> > An: Robert Buckley <robertdbuck...@yahoo.com>; PostGIS Users Discussion > <postgis-users@postgis.refractions.net> > Gesendet: 22:33 Dienstag, 28.Februar 2012 > > Betreff: Re: [postgis-users] how to create a hole in a polygon table? > > I was thinking of something like this, but it doesn't work. > Unfortunately Geoserver doesn't have the ability to create offset > lines, so there's no nice way to do this without doing a little > negative buffer on the shape (which incidentally, you could do using > the geometry transformation facility on the fly > http://docs.geoserver.org/stable/en/user/styling/sld-extensions/geometry-transformations.html > > P > > <?xml version="1.0" encoding="ISO-8859-1"?> > <StyledLayerDescriptor version="1.0.0" > xmlns="http://www.opengis.net/sld"; > xmlns:ogc="http://www.opengis.net/ogc"; > xmlns:xlink="http://www.w3.org/1999/xlink"; > xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"; > xmlns:gml="http://www.opengis.net/gml"; > xsi:schemaLocation="http://www.opengis.net/sld > http://schemas.opengis.net/sld/1.0.0/StyledLayerDescriptor.xsd";> > <NamedLayer> > <Name>USA states</Name> > <UserStyle> <Name>population</Name> > <Title>United States</Title> > <Abstract>A Simple Brush Style</Abstract> > <FeatureTypeStyle> > <Rule> > <LineSymbolizer> > <Stroke> > <GraphicStroke> > <Graphic> > <ExternalGraphic> > <OnlineResource xlink:type="simple" > xlink:href="file:///Users/pramsey/green_bottom.gif" /> > <Format>image/gif</Format> > </ExternalGraphic> > </Graphic> > </GraphicStroke> > <CssParameter name="stroke-linecap">round</CssParameter> > <CssParameter name="stroke-dasharray">1 0 1 0</CssParameter> > </Stroke> > </LineSymbolizer> > </Rule> > </FeatureTypeStyle> > </UserStyle> > </NamedLayer> > </StyledLayerDescriptor> > > > On Tue, Feb 28, 2012 at 12:00 PM, Robert Buckley > <robertdbuck...@yahoo.com> wrote: >> Thanks for the advice. >> >> Unfortunately I don´t understand what you have just told me....half-brush? >> half-circle? >> >> are these sld specifications?...I am delivering wms data using sld´s to >> style the data. >> >> could you please clarify? >> >> cheers, >> >> Rob >> >> ________________________________ >> Von: Paul Ramsey <pram...@opengeo.org> >> An: Robert Buckley <robertdbuck...@yahoo.com>; PostGIS Users Discussion >> <postgis-users@postgis.refractions.net> >> Gesendet: 19:20 Dienstag, 28.Februar 2012 >> Betreff: Re: [postgis-users] how to create a hole in a polygon table? >> >> Rather than geometry processing, work on your rendering engine. You >> can usually achieve an interior band (the classic National Geographic >> political boundary, yes?) with a half-brush (rather than a full >> circle, use a half-circle), and just ensuring your polygons are >> consistently oriented. >> >> P. >> >> On Tue, Feb 28, 2012 at 10:04 AM, Robert Buckley >> <robertdbuck...@yahoo.com> wrote: >>> Hi, >>> >>> I am trying to create an inner buffer of a polygon geometry table. >>> Unfortunately this is the only way I can think of which will enable me to >>> make a certain symbol for a polyon layer. The SLD Filter "difference" >>> might >>> do it, but it needs to be nested and i´m not sure if this is possible. >>> >>> anyway....My polygons need to be symbolized with a thin outline AND an >>> inside Buffer of 3 mm(150m at a scale of 1:50 000)....in essence just an >>> inside ring. >>> >>> This means I need to first buffer my polygon geometry and then substract >>> the >>> buffer from the original polygon. = ST_Difference (i think!?!) >>> >>> my attempt created some geometries but not what I was expecting... >>> >>> create view rrop08.rrop_01_13_innerbuffer AS >>> >>> SELECT ST_Difference(a.st_buffer, b.the_geom) >>> >>> FROM rrop08.rrop_01_13_buffer a, rrop08.rrop_01_f b; >>> >>> >>> rrop08.rrop_01_f = the original polyon >>> >>> rrop08.rrop_01_13_buffer = the inner buffer >>> >>> >>> >>> >>> >>> _______________________________________________ >>> postgis-users mailing list >>> postgis-users@postgis.refractions.net >>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>> >> >> >> >> _______________________________________________ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > > > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
