[postgis-users] working with multipolygons

[lplateandy]

Hi,

Looking for some tips about the right direction to take when tidying up some
multi-polygon data. I 
have lots of 2 by 2 kilometre chunks defining a type of coverage.

The information for each 2 by 2km chunk has been merged into multi-polygons,
it may have holes as small as 25 by 25 metres or equally the area may only
be partly filled along with little 25 by 25 metre islands.

Is there a method to delete parts of a multi-polygon for example:

1) Any elements which represent a hole
2) Any elements below a certain threshold size

I can imagine that dissolving the multi-polygon would allow me to apply
changes to the islands but am not sure about the holes


I also found that when i tried to carry out some queries such as
ST_SimplifyPreserveTopology or ST_Envelope i get null areas or bounding
boxes of just one of the holes - as though the action is just being applied
to one of the elements in the polygon - perhaps the first one - is that the
case?


Any pointers to get me started would be much appreciated.

Thanks in advance

Andy
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