Distance maybe ? Guillaume
Le mercredi 18 novembre 2009 à 09:27 -0500, Worth Lutz a écrit : > I'm learning a lot here. > > I now understand how to get the buffered geometry quickly. > > I am using the buffered geometry to use PHP mapscript to select parcel > intersecting the buffered geometry. > > $layer->queryByShape($bufferedShape); > > Are you telling me that there is a better/faster way to do this? > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Ludwig > Kniprath > Sent: Wednesday, November 18, 2009 3:01 AM > To: [email protected] > Subject: Re: [mapserver-users] PHP mapscript $shape->buffer() takes a > longtime > > We had the same problem. In deed the buffer-algorithm is very expensive, > especially with large polygons and a large buffer-radius. If you use > Postgis, you can simplify the Polygon with ST_Simplify or > ST_SimplifyPreserveTopology in dependency from scale and buffer-radius, this > will make the buffer-process much faster without significant loss of > quality. You can do this on runtime on your original data with dynamic > PostGIS-queries. If you don't use PostGis, you have to create simplified > layers. > > Pseudo-PHP-PostGIS-SQL: > SELECT ... > ST_SetSRID(ST_BUFFER(ST_SIMPLIFY($geometery_field,$simplify_tolerance),$buff > er_radius, $number_of_segments),$srid)::geometry ...FROM... > > And don't use the buffered polygon for geo-queries, there are faster ways in > PostGIS and Mapserver. > > Regards > Ludwig Kniprath > > > > >I'm trying to buffer a shape returned from a point query on a polygon layer > >of parcels. > > > > > > > >When I try to use: > > > > > > > >$bufferedShape = $shape->buffer(200); > > > > > > > >I get back a fatal error: Maximum execution time of 30 seconds exceeded. > > > >I know that this is a php error message and that I could increase the > >allowable execution time. > > > > > > > >If I use a buffer distance of 175 I get results. > > > > > > > >Should it take such a long time to but a buffer around this parcel? It is > a > >large parcel with one corner being a long curve like a quarter of a circle > >and another section on one side being a half circle. > _______________________________________________ > mapserver-users mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-users > > _______________________________________________ > mapserver-users mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/mapserver-users > _______________________________________________ mapserver-users mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/mapserver-users
