[postgis-users] Intersection errors

[Darren Houston]

Hi Sean,

I'm correct in assuming the multipolygon posted is the geometry at 
layer=3? I received a false isvalid on that multipolygon.

'POSTGIS="1.0.1" GEOS="3.0.0" PROJ="Rel. 4.4.9, 29 Oct 2004" USE_STATS 
DBPROC="0.3.0" RELPROC="0.3.0"'

I'm in a rush, but I promise to look at it more tomorrow.

Darren H.

Sean M. Montague wrote:

>Several months ago I had posted on this list about some intersection
>problems I was having, but was never able to solve it.  I gave up with
>the intentions of revisiting it if version 1 did not fix the bug.  It
>has not.  The problem arises when trying to intersect one poly with
>another when it has holes.  If the intersecting poly partially overlays
>a hole, it throws an error.  Below is the geometry with holes and the
>two intersection statements.  The first works, it does not intersect any
>part of the hole.  The second fails.  I've tried to keep it simple.
>Thanks.
>
>Sean
>
>
>GeometryFromText('MULTIPOLYGON(((-244339 1210399, -244339 1541250, 21058
>1541250, 21058 1210399, -244339 1210399)),((-39283 1521307, -57692
>1518238, -64340 1511591, -62805 1497784, -54112 1494716, -45931 1494716,
>-40306 1494204, -38260 1493693, -34681 1482443, -42862 1471705, -50021
>1460966, -51044 1448182, -41840 1437955, -27522 1431307, -8601 1422614,
>603 1409318, 92 1392955, -13715 1377103, -46953 1370455, -68942 1365341,
>-91442 1342841, -91442 1309092, -81726 1303467, -2976 1329546, 13899
>1358182, 14921 1431818, -7067 1513125, -39283 1521307)))',32767)
>
>SELECT intersection(the_geom, PolygonFromText('POLYGON((-341457 1496785,
>-161897 1496785, -161897 1317225, -341457 1317225, -341457
>1496785))',32767))
>As the_geom
>>From test_02
>WHERE layer='3'
>AND the_geom && PolygonFromText('POLYGON((-341457 1496785, -161897
>1496785, -161897 1317225, -341457 1317225, -341457 1496785))',32767);
>
>Returns:
>"0103000020FF7F000001000000050000000000000098D30DC1000000006919344100000
>00098D30DC100000000D1D636410000000048C303C100000000D1D636410000000048C30
>3C100000000691934410000000098D30DC10000000069193441"
>
>
>
>SELECT intersection(the_geom, PolygonFromText('POLYGON((-213394 1467529,
>-33834 1467529, -33834 1287969, -213394 1287969, -213394
>1467529))',32767))
>As the_geom
>>From test_02
>WHERE layer='3'
>AND the_geom && PolygonFromText('POLYGON((-213394 1467529, -33834
>1467529, -33834 1287969, -213394 1287969, -213394 1467529))',32767);
>
>Returns:
>NOTICE:  AssertionFailedException: EdgeRing::computePoints: found null
>Directed Edge
>
>ERROR:  GEOS Intersection() threw an error!
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