[postgis-users] Problem with ST_Within, Polygons and Multipolygons

Jorge Arévalo jorge.arevalo at gmail.com
Thu May 7 17:11:02 PDT 2009


Hi Kevin,

Wow, some new concepts here. Now, I'm not in front of my computer, but I'll
try these operations asap. I think that I've a couple of questions about
them, but I'll wait.

Many thanks!

Jorge



On Fri, May 8, 2009 at 12:16 AM, Kevin Neufeld <kneufeld at refractions.net>wrote:

> Yeah, that's a good question.  You could try to break-down your ocean
> geometry into the raw linework, properly node the linework, and then rebuild
> your polygons.
>
> ie.
> -- Extract the linework
> CREATE TABLE water_poly_boundaries AS
> SELECT st_collect(st_boundary(the_geom)) AS the_geom
> FROM water_polys ;
>
> -- Node the linework
> CREATE TABLE water_boundaries_noded AS
> SELECT st_union(the_geom, st_startpoint(the_geom)) AS the_geom
> FROM water_poly_boundaries ;
>
> Then use buildarea or polygonize to rebuild the polygons.
>
> -- Kevin
>
> Jorge Arévalo wrote:
> ...
>
>> Oh, and thanks again for your response to my original question. It helped
>> me a lot... Maybe is it time to ask for new data, without errors? If not,
>> how should I "clean" my data? I tried with ST_Buffer(geom, 0.0) (I read in
>> this link
>> http://www.bostongis.com/postgis_extent_expand_buffer_distance.snippetthat is useful to repair data with self-interesections), but doesn't seem to
>> work for me...
>>
>> Regards
>> Jorge
>>
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