[postgis-users] Problem cleaning invalid geometries

[Paul Ramsey]

You could use ST_Dump() to split your multipolygon up and then run
validity check/fix on the individual components...?
P

On Fri, Aug 20, 2010 at 9:44 AM, L Bogert-OBrien <dlawbob at ncf.ca> wrote:
> Hi,
>
> I am just wondering if there is a way to minimize the extent on which
> the cleangeometry() function will act, or rewrite it so that it only
> checks out the parts of the multipolygon near the problem area, rather
> than having to wait for it to check the validity of all the pieces of
> the multipolygon.  Then maybe I wouldn't have to wait days for it to return.
>
> Any ideas?
>
> Thanks,
>
> Loretta
>
>>I am not sure what you are trying to say with this, but the geometry
>>that I am trying to clean is a multipolygon, not a collection.  Yes, it
>>is very big and has many points in the multipolygon, since it is the
>
>>Baffin region, but it is not a collection.  ST_geometrytype returns
>>multipolygon for it.
>
> There are many possibly kind of invalidity.
>
> If the invalidity is a self-intersect,
> of course the ST_MakeValid() could split the polygon on the self-intersect and produce another multipolygon with one more part.
>
> But if , for example, you multipolygon is invalid because it has a hole of type Linestring, or because it has two part that are touching along a line.
>
> More probably the st_makevalid could be return a geometrycollection().
>
>
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòùo
> -----------------
>
>
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