This is an example of a known issue with GEOS/JTS buffering. The
problem occurs when using a relatively large buffer distance on
geometries which have a large number of vertices which are relatively
dense (i.e. the distance between adjacent vertices is much smaller than
the requested buffer distance).
A couple of ways to avoid this problem are:
- simplify the input geometry using a tolerance which gets rid of most
of the very dense vertices (use a tolerance of say from 1% to 10% of the
buffer distance)
- buffer the geometry mulitple times, starting with a very small buffer
distance and gradually increasing it
Andi Vajda wrote:
Hi,
Running on Mac OS X 10.5.4 with 4gb of RAM and postgis_full_version() of
POSTGIS="1.3.2" GEOS="3.0.0-CAPI-1.4.1" PROJ="Rel. 4.6.0, 21 Dec 2007"
USE_STATS
I get a runaway postgres process if I call ST_Buffer(shape, 0.1) on
the attached WKT shape. My postgresql server eventually exhausts the
swap space over 9gb.
It's a polygon with 12271 points representing the state of Alabama.
When converted to GeoJSON it renders correctly at [1].
Is this shape triggering some bug ?
Thanks !
Andi..
[1] http://openlayers.org/dev/examples/vector-formats.html
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Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022
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