[postgis-users] Problems with ST_OffsetCurve

[Sandro Santilli]

On Mon, Feb 03, 2014 at 11:43:37AM +0300, jakob ventin wrote:
> 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

Sounds like a robustness problem. It would be interesting to
see if using a fixed PrecisionModel solved the issue.
You can file a ticket for GEOS, an XML test for GEOS would
be able to test with both floating and fixed PrecisionModel.

If fixed precisionmodel solves it this would be yet another
reason to expose support for that into PostGIS...

--strk;