Take a look at the PostGIS wiki function fnpoly_to_rings and see if it does something like what you are looking for.
http://postgis.refractions.net/support/wiki/index.php?plpgsqlfunctions You might need to modify it slightly to create single lines and then the polygon id of left and right since it maintains the number of records simply by turning the MULTIPOLYGON into MULTILINESTRINGS which would require leaving out the ST_Collect step and then doing an SQL update after the fact based on equality of line geometries. Only caveate - as some people have mentioned (generate_series degrades for large numbers - I haven't had big enough geometries to run into the issue) . Hope that helps, Regina -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Lee Hachadoorian Sent: Monday, March 10, 2008 1:21 AM To: [email protected] Subject: [postgis-users] Turn a Polygon into Lines I'm looking through the PostGIS reference, and I can't seem to find a way to take a geometry of polygons and turn it into lines. What I'm looking for is something like the ArcGIS Feature to Line geoprocessor, which will create a line shapefile where each feature is an arc representing the boundary between neighboring polygons with a field indicating the ids of the polygon on either side. Functions like ST_MakeLine require point geometries, and I don't see anything else that seems to be what I'm looking for. Any ideas would be welcome. Thanks, Lee Hachadoorian PhD Student in Geography Program in Earth & Environmental Sciences CUNY Graduate Center _______________________________________________ postgis-users mailing list [email protected] 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 [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
