[postgis-users] simplifying (homogenize) a polygon

[Nicolas Ribot]

Hi Denis,

In your example, I don't understand how the parts of your
multipolygons can be adjacent. Are they valid ?
Do you have a visual example ?

Thank you

Nicolas


On 21 November 2013 07:32, Denis Rouzaud <denis.rouzaud at gmail.com> wrote:
> Hello Rémi,
>
> I was hoping a simplest request without enabling topology but thanks anyway!
>
> Cheers,
>
> Denis
>
>
> On 20. 11. 13 18:26, Rémi Cura wrote:
>
>
> From what I understand of your needs, Postigs topology was designed for
> this.
> Cheers,
>
> Rémi-C
>
>
> 2013/11/20 Denis Rouzaud <denis.rouzaud at gmail.com>
>>
>> Hi all,
>>
>> I am drawing some multipolygons in QGIS and sometimes, I have parts of
>> them which are adjacent and I'd like to homogenize them to have less parts
>> and no adjacent parts.
>>
>> I could do this with a quite complex method:
>>
>> 1. get the number of parts Z:
>> SELECT ST_NumGeometries(geometry) FROMmytable WHERE id=123;
>>
>> 2. do the simplification using ST_CollectionHomogenize:
>> SELECT
>> ST_Multi(ST_CollectionHomogenize(ST_Union(ST_GeometryN(geometry,n)))) FROM
>> mytable CROSS JOIN generate_series(1,Z) n WHERE id = 123;
>>
>> 3. update manually the result in the table (copy paste).
>>
>>
>> Does someone has something more straightforward???
>>
>> Thanks a lot!
>>
>> Best regards,
>>
>> Denis
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>
>
>
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