[postgis-users] Intersection errors

[Paul Ramsey]

Sean,

Change your script, it's not writing things out right... you are writing 
MULTIPOLYGON parts instead of POLYGON parts. If you wrote polygon parts, 
the hole would be a hole instead of another polygon...

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)))

Note: "),(" instead of ")),((". Double note: Arcview *does* support 
multipolygons, so you have to write those out correctly too (otherwise 
you'll create more invalid geometries, by treating multiparts as holes).

Paul

Sean M. Montague wrote:

> It's a hole.  It should be valid...I think.  What about islands in a
> lake?  The only time I have a problem with them is when I intersect one.
> 
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Paul
> Ramsey
> Sent: Tuesday, June 07, 2005 11:35 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] Intersection errors
> 
> It's not valid, because legal multipolygons do not have parts that 
> interact. Your multipolygon has two parts and one is completely 
> contained in the other. No cookie for you!
> 
> Paul
> 
> Sean M. Montague wrote:
> 
>>Correct, below is the insert statement I construct from AV 3 using
>>Avenue.  I'm not sure about the isvalid.  Is that what you get when
>>trying to insert it?  Thanks.
>>
>>Sean
>>
>>INSERT INTO "test_02" ("objectid","name","layer","the_geom") VALUES
>>('3','3','3',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))
>>
>>
>>-----Original Message-----
>>From: postgis-users-bounces at postgis.refractions.net
>>[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
>>Darren Houston
>>Sent: Monday, June 06, 2005 8:30 PM
>>To: PostGIS Users Discussion
>>Subject: Re: [postgis-users] Intersection errors
>>
>>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.
>>_______________________________________________
>>postgis-users mailing list
>>postgis-users at postgis.refractions.net
>>http://postgis.refractions.net/mailman/listinfo/postgis-users
> 
> 
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