[postgis-users] Problem cleaning invalid geometries

[L Bogert-OBrien]

Hi,

Thanks for all the suggestions.  I found that a big part of the problem
was that I had not set up indexes on the geometries.  Once I did that,
the functions worked much faster.

Regards,

Loretta

----- Original Message -----
From: Paul Ramsey <pramsey at opengeo.org>
Date: Friday, August 20, 2010 12:53 pm
Subject: Re: [postgis-users] Problem cleaning invalid geometries

> 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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