[postgis-users] return boundary

[Travis Kirstine]

I don't think that the geom union would in combination with the
boundary would attach the island to the mainland.  I don't think that
there is a simple answer to my problem but I have attached a pic to
help illustrate what I'm trying to accomplish.

Regards

2008/11/21 Lee Meilleur <lee.meilleur at gis.leg.mn>:
>
> Howabout ST_BOUNDARY(ST_UNION(the_geom))
>
> ________________________________________
> From: postgis-users-bounces at postgis.refractions.net [postgis-users-bounces at postgis.refractions.net] On Behalf Of Burgholzer,Robert [rwburgholzer at deq.virginia.gov]
> Sent: Friday, November 21, 2008 12:45 PM
> To: PostGIS Users Discussion
> Subject: RE: [postgis-users] return boundary
>
> So,
> Do you need to iterate through the sub-polygons in your multi and get a
> boundary of each?
>
> r.b.
>
> Robert W. Burgholzer
> Surface Water Modeler
> Office of Water Supply and Planning
> Virginia Department of Environmental Quality
> rwburgholzer at deq.virginia.gov
> 804-698-4405
> Open Source Modeling Tools:
> http://sourceforge.net/projects/npsource/
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
> Travis Kirstine
> Sent: Friday, November 21, 2008 10:51 AM
> To: PostGIS Users Discussion
> Subject: Re: [postgis-users] return boundary
>
> Thanks Obe
> But I'm looking for something that returns the boundary of all the
> selected features combined and attached.  Something that has the
> abilty to take the group the features together like convex hull but
> keep the detail of the of the edge like boundary.
>
> 2008/11/21 Obe, Regina <robe.dnd at cityofboston.gov>:
>> How about ST_Boundary?
>>
> http://postgis.refractions.net/documentation/manual-svn/ST_Boundary.html
>>
>> -----Original Message-----
>> From: postgis-users-bounces at postgis.refractions.net
>> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
>> Travis Kirstine
>> Sent: Friday, November 21, 2008 10:18 AM
>> To: PostGIS Users Discussion
>> Subject: [postgis-users] return boundary
>>
>> I have a multipolygon that has consists mainland and island polygons.
>> I need to generate a single polygon / line that represent the boundary
>> of the multipolygon as a whole, something like a convex hull but
>> keeping the detail of the outer rings and joining the islands to the
>> mainland.  I have been try different combos of convex hull, buffer and
>> difference but can't get what I'm looking for.
>>
>> Any thoughts would be greatly appreciated
>>
>> Regards
>>
>> --
>> Travis K.
>>
>> Toronto, Canada
>> ------------------------------------------------------------
>> "She knows there's no success like failure
>> And that failure's no success at all."
>> -Bob Dylan-
>> ------------------------------------------------------------
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>> -----------------------------------------
>> The substance of this message, including any attachments, may be
>> confidential, legally privileged and/or exempt from disclosure
>> pursuant to Massachusetts law. It is intended
>> solely for the addressee. If you received this in error, please
>> contact the sender and delete the material from any computer.
>> _______________________________________________
>> postgis-users mailing list
>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>
>
>
> --
> Travis K.
>
> Toronto, Canada
> ------------------------------------------------------------
> "She knows there's no success like failure
> And that failure's no success at all."
> -Bob Dylan-
> ------------------------------------------------------------
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
> _______________________________________________
> postgis-users mailing list
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>



-- 
Travis K.

Toronto, Canada
------------------------------------------------------------
"She knows there's no success like failure
And that failure's no success at all."
-Bob Dylan-
------------------------------------------------------------
-------------- next part --------------
A non-text attachment was scrubbed...
Name: example.JPG
Type: image/jpeg
Size: 17494 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20081124/368eb1b0/attachment.jpe>