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Re: build a polygon from points

by Caspa :: Rate this Message:

Hi, thanks for that,
those are colunm in the table :

coord1 | coord2 | coord3 | coord4 | pol
----------------------------------------------------+--------------------
geom_data | geom_data | geom_data | geom_data | I WANT THIS

I tried with this but didnt work;

SELECT ST_MakePoly(ST_MakeLine(coord1, coord2, coord3, coord4, coord5, coord1 ) from table

the problem is that I can't make i line from more than two points ( i'm using postgis v 1.3.5 and geometry ST_MakeLine(geometry[] point_array); doesn't work)
I'm trying to figure out how to use

geometry ST_MakeLine(geometry set pointfield);

but how do I build a geometry set pointfield???
sorry...really beginner!!

2009/6/22 Paragon Corporation <lr@...>

Andrea,
Are those individual records or columns in the table?

Take a look at ST_MakeLine, ST_MakePolygon, ST_BuildArea

http://postgis.refractions.net/documentation/manual-svn/ST_MakeLine.html

http://postgis.refractions.net/documentation/manual-svn/ST_BuildArea.html

http://postgis.refractions.net/documentation/manual-svn/ST_MakePolygon.html

You build a line from points with ST_MakeLine and then do a ST_BuildArea or
ST_MakePolygon depending on your desired effect.

Leo

-----Original Message-----
From: postgis-users-bounces@...
[mailto:postgis-users-bounces@...] On Behalf Of Caspa
Sent: Monday, June 22, 2009 10:15 AM
To: postgis-users@...
Subject: [postgis-users] build a polygon from points

Hi everybody,
I'm new to postgis...
how can i build a polygon starting from points and not from x,y coord?

i have a table built like this:

point1 | point2 | point3 | point4 | polygon

guess i have to use MakeLine and MakePolygon but i can't fugure out why...
thanks in advance

Andrea

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