[postgis-users] Geomunion problems

[palmerj at xtra.co.nz]

Hi,

I'm trying to complete a few polygon dissolves and geos is throwing a couple of error messages under 2 different queries. The first query is a simple union of polygons which are spatially very close to each other. 

When I complete the following command:

"SELECT geomunion(shape) FROM mesh_block"

I get the following error msg:

NOTICE:  TopologyException: Directed Edge visited twice during ring-building at  (9.16511,-44.6877)

ERROR:  GEOS union() threw an error!

I have attached a file with the geometries and table definition if that helps.

I'm also running geomunion on a different larger dataset and I’m getting another problem:

SELECT sa.id, 
       sa.name, 
       sa.code, 
       geomunion(mb.shape) as shape
FROM   crs_mesh_blk mb,
       crs_mesh_blk_area mba,
       crs_statist_area sa
WHERE  mb.id = mba.mbk_id
AND    mba.stt_id = sa.id
AND    sa.sav_area_class = 'TA'
GROUP  BY sa.id, sa.name, sa.code;

NOTICE:  TopologyException: no outgoing dirEdge found (9.18236,-44.6848)

ERROR:  GEOS union() threw an error!

I have not attached this data for testing, as it quite large :(

Note I have completed isvalid tests on all of the geometries in both dataset and everything returns true.

My version of postgis is:

SELECT postgis_full_version();
POSTGIS="1.0.4" GEOS="2.1.4" PROJ="Rel. 4.4.9, 29 Oct 2004" USE_STATS DBPROC="0.3.0" RELPROC="0.3.0"

Any help on these errors and how to resolve them would be greatly appreciated.

Cheers
Jeremy Palmer

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