LiN YongHeng,
your geometry is invalid since first you don't have enough points to form a
polygon after you remove the dupes and second you have self intersections.
Therefore the union is undefined at best.
Hope that helps,
Regina
-----Original Message-----
From: [email protected] on behalf of LiN YongHeng
Sent: Sun 4/12/2009 9:17 PM
To: [email protected]
Subject: [geos-devel] question about GEOSUnion?
Hello everyone,
I have a question about GEOSUnion().
I give value to g1 and g2 like below:
GEOSGeom g1 = "POLYGON ((1 3, 1 3, 1 6, 1 6, 1 3))" and GEOSGeom g2 =
"POLYGON ((1 3, 1 3, 1 6, 1 6, 1 3))" , but if I make union operation
like GEOSGeom g3 =
GEOSUnion(g1, g2), it give me result like "GEOMETRYCOLLECTION EMPTY".
Does anyone can tell me why?
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