[postgis-users] how to create a hole in a polygon table?

[Robert Buckley]

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 
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