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<P>Hi David,</P></DIV>
<P>The areas returned as 'geometrycollection' are well within the clipped area. As a matter of fact, some of the sub-geoms are complete polygons designated as such in the geometrycollection. For example:</P>
<P>GEOMETRYCOLLECTION(LINESTRING(234812.51 463497.84, ...... , 234812.51 463497.84),LINESTRING(234812.51 463497.84, ...... , 234812.51 463497.84),POLYGON((234812.51 463497.84, ...... , 234812.51 463497.84),(234812.51 463497.84, ...... , 234812.51 463497.84),(234852.51 463547.84, .... ,234852.51 463547.84)))</P>
<P>As you can see, many of these sub-geomertries start and end at a same point (i.e. they define a polygon). I've attached a sample image of the resulting clipped geometry. The original layer is clipped with a triangle whose corner is seen at the bottom-right edge of the geometry. The areas in gray were succesfully identified as (multi)polygons, the white areas inside the triangle shape were identified as geometrycollection. Oddly enough these white areas return as properly indentified polygons if I use a slightly different clip shape.</P>
<P>Manny</P>
<P>> </P>
<DIV></DIV>> > Why would INTERSECTION(geom 'of type Multipolygon',
<DIV></DIV>> > geom 'of type Polygon)
<DIV></DIV>> > sometimes return a geom of type 'geometrycollection'
<DIV></DIV>> > as opposed to type
<DIV></DIV>> > polygon or multipolygon?
<DIV></DIV>>
<DIV></DIV>>It depends on the type of intersection you have with
<DIV></DIV>>polygons and multipolygons: crosses, contains,
<DIV></DIV>>overlaps.
<DIV></DIV>>
<DIV></DIV>>It might be that the intersection is (lines +
<DIV></DIV>>points), not multipolygon. So that's the reason why
<DIV></DIV>>it could be a geometrycollection.
<DIV></DIV>>
<DIV></DIV>
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