No, once you've got the shape it probably doesn't matter much. The patch associated with #2753 would allow you to simplify in MapScript. It's not complete though as it's PHP only. Will pursue adding to 5.6...
Steve >>> On 11/18/2009 at 4:30 PM, in message <8be0b8dc92ae4f3eacc4d17786c52...@worthlaptop>, "Worth Lutz" <[email protected]> wrote: > I need the buffered shape to draw it. Once I have it does it make any > difference is how I do the query? > > Is the enhancement described in Ticket #2753 implemented in 5.6 for PHP > mapscript? Or will I need to take my shape to postGIS to simplify before > buffer? > > -----Original Message----- > From: Steve Lime [mailto:[email protected]] > Sent: Wednesday, November 18, 2009 9:35 AM > To: [email protected]; [email protected]; > [email protected] > Subject: RE: [mapserver-users] PHP mapscript $shape->buffer() takes > alongtime > > You may not need to buffer at all. The shape query honors layer tolerances > so > you can find parcels within a certain distance. So if $layer->{tolerance} is > 500 > and $layer->{toleranceunits} is 'meters' then your shape query will find all > > features within 500 meters. If you don't need to draw the buffered shape > then > this might be a good option. > > Steve > >>>> "Worth Lutz" <[email protected]> 11/18/09 8:23 AM >>> > 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
