[postgis-users] Polygonize

[Dustin Sampson]

Hey Everyone,

   I'm building a "clean" type function that cleans up overlapping 
polygons within a table (without using the ST_Union function) but am 
running into a few snags. 

Basically what I'm doing is

    1) Converting polygons -> lines
    2) Converting lines -> points
    2) Add intersecting nodes where lines cross.
    3) Build lines from points & nodes
    4) Polygonize new lines.

I can get to stage 3 (so far reliabily) but at stage 4 it doesn't seem 
to be building polygons consistently in my testing.  I've attached my 
original polygon table (testset.sql), my noded lines (noded_lines.sql) 
and my function which is in plpython  (tnrg_clean.sql).

Does anyone know what is required for the polygonize function, am I 
missing some stage to prep the line work before converting to polygons.
Any help would be appreciated. 

Thanks for the help,
Dustin Sampson


-------------- next part --------------
A non-text attachment was scrubbed...
Name: noded_lines.sql
Type: text/x-sql
Size: 213169 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20080612/ab6e3955/attachment.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: testset.sql
Type: text/x-sql
Size: 40670 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20080612/ab6e3955/attachment-0001.bin>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: tnrg_clean.sql
Type: text/x-sql
Size: 14533 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20080612/ab6e3955/attachment-0002.bin>