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List:       postgis-users
Subject:    [postgis-users] Convert lines to polygon
From:       Brent Wood <pcreso () pcreso ! com>
Date:       2007-07-27 22:57:56
Message-ID: 725848.14088.qm () web33202 ! mail ! mud ! yahoo ! com
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Can anyone help clarify how teh various make polygon functions work?

I have a set of roughly parallel lines (depth contours)

The table also includes lines crossing these contour lines

20m 50m 100m  150m
|   |    |     |
------------------- 
| A | B  | C   |
|   |    |     |
-------------------
| D | E  | F   |
|   |    |     |
-----------------
|   |    |     |

I want to take all these lines & build polygons from them, generating vertices 
where the lines cross (polygons ABCDEF)

I thought this was what polygonize() did, but having had a brief play with it,
I believe this is not true, instead all it seems to do is turn closed lines
into polygons, & perhaps include holes from closed lines inside other closed
lines.

Is there any way in PostGIS to take a set of intersecting lines as above &
deriving the polygons from them? 


Thanks,

  Brent Wood
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