[postgis-users] TopologyException: side location conflict

[Stefan Zweig]

hi @ all,

i have following problem with the postgis WITHIN method:

i am trying to check whether some polygons from one layer/table are within a polygon from another layer/table and i am doing this with this sql command:

SELECT p."POSTCODE"
FROM _countys b AS b, postcodes AS p
WHERE b."NAME"='florida' AND p."the_geom" @ b."the_geom" = true
AND WITHIN(p."the_geom", b."the_geom") = true
;

this works fine but takes i while to be procedured. so i wanted to make the within check faster by simplifying the source geometries (EPSG: 4326):


SELECT p."POSTCODE"
FROM _countys b AS b, postcodes AS p
WHERE b."NAME"='florida' AND p."the_geom" @ b."the_geom" = true
AND WITHIN(simplify(p."the_geom",0.001), simplify(b."the_geom",0.001)) = true
;

but then i get the following error:

NOTICE:  TopologyException: side location conflict (-81.0351,26.6027,26.6027)

ERROR: GEOS within() threw an error!
SQL Status:XX000

i am wondering why the within operator does not work with simplified coordinates / geometries.

btw.: i does not seem that this error occurs with any within/simplify usage, only in some cases.

i appreciate any help.

stefan
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