[postgis-users] snapping all close-by lines in a set of 500, 000

[Sandro Santilli]

On Mon, Jun 18, 2012 at 04:31:18PM +0200, Nicolas Ribot wrote:
> > Hello Nicolas,
> > thank you for the reply. I don't have enough experience with postgis to
> > understand how your suggestion helps.
> > Do you suggest to loop over all linestrings (which is really slow!) after
> > st_dumppoints, or is there a single command that does the snapping at
> once?
> > What is the advantage of the intermediate points table? st_snap works
> with a
> > given tolerance, or st_distance can help to select close-by lines... where
> > do the points come in?
> >
> 
> I find useful to explode a linestring into its points to be able to
> identify pseudo-parallel lines: st_distance is not enough as perpendicular,
> touching lines will return 0 for the distance though they are not close to
> each other at each location.

You could also look at ST_HausdorffDistance.

--strk;

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