[postgis-users] Problems with ST_OffsetCurve

[jakob ventin]

Hello all,
I am using ST_OffsetCurve function to calculate offsets for lines and polygons. I have a quit large amount of data, several tens of thousands of features which I have to do these calculations for in an automated processs. Now I have run into a problem: St_OffsetCurve crashes for some geometries, e.g this geometry and value -16 for ST_OffsetCurve:
 SELECT ST_OffsetCurve(geometry_line,-16) FROM table WHERE id = 111;ERROR:  GEOSOffsetCurve: TopologyException: assigned depths do not match at 346051.04711531324 6861597.9481203193

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
With  ST_OffsetCurve values -15 or -17 this runs fine.

SELECT ST_IsSimple(geometry_line) FROM table WHERE id = 111; st_issimple------------- t(1 row)
SELECT ST_IsValid(geometry_line) FROM table WHERE id = 111; st_issimple------------- t(1 row)
As seen from http://trac.osgeo.org/postgis/ticket/2496 a similar problem is reported, which is considered solved by upgrading to latest (?) GEOS & PostGIS version. However, I run this version:
 POSTGIS="2.1.0 r11822" GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0, 6 March 2012" LIBXML="2.7.6" LIBJSON="UNKNOWN"
and the problem remains.
I have seen some workarounds using ST_SimplifyPreserveTopology. It reduces the problem but doesn't solve it fully. The dataset I need to process is big, and I need to calculate offsets with different parameter values.
Does anyone know if this is a bug? Any ideas on how to proceed?
Best regards,
Jakob Ventin



 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20140203/6a8f54ae/attachment.html>