[postgis-users] TopologyException and ST_Intersection

[Derek Morgan]

I am attempting to get the area of intersection between to vector
polygon tables in PostGIS.  I am using the following SQL:

SELECT ctys.fips,
       Sum(ST_Area(ST_Intersection(ctys.the_geom,pads.the_geom)))
FROM counties4269 ctys,
     padus4269 pads
WHERE ST_Overlaps(ctys.the_geom, pads.the_geom)
GROUP by ctys.fips;

However, my query returns the following error:  TopologyException:
side location conflict at 1.66342e+06 1.99261e+06
ERROR:  GEOS overlaps() threw an error!

I am guessing that this has to do with some topology issues.  Any help
or pointers would be greatly appreciated.

Thanks,
Derek