[postgis-users] working with multipolygons

[lplateandy]

Hi Simon,

Brilliant - exactly what i needed, fully explained and with working examples
too.

Just need a strong coffee and a bit of patience now...

Andy



Simon Greener-3 wrote:
> 
> Andy,
> 
> Is this of any use to you:
> 
> http://www.spatialdbadvisor.com/postgis_tips_tricks/92/filtering-rings-in-polygon-postgis
> 
> regards
> Simon
> On Sat, 09 Oct 2010 08:11:24 +1100, lplateandy <andy at centremaps.co.uk>
> wrote:
> 
>>
>> 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
> 
> 
> -- 
> SpatialDB Advice and Design, Solutions Architecture and Programming,
> Oracle Database 10g Administrator Certified Associate; Oracle Database 10g
> SQL Certified Professional
> Oracle Spatial, SQL Server, PostGIS, MySQL, ArcSDE, Manifold GIS, FME,
> Radius Topology and Studio Specialist.
> 39 Cliff View Drive, Allens Rivulet, 7150, Tasmania, Australia.
> Website: www.spatialdbadvisor.com
>    Email: simon at spatialdbadvisor.com
>    Voice: +61 362 396397
> Mobile: +61 418 396391
> Skype: sggreener
> Longitude: 147.20515 (147° 12' 18" E)
> Latitude: -43.01530 (43° 00' 55" S)
> GeoHash: r22em9r98wg
> NAC:W80CK 7SWP3
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
> 
> 

-- 
View this message in context: http://old.nabble.com/working-with-multipolygons-tp29919084p29920910.html
Sent from the PostGIS - User mailing list archive at Nabble.com.