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Re: build a polygon from points

by Nicklas Avén :: Rate this Message:

you saw my second answer?

st_makeline should work if you just define an apoint array like

array[point1, point2,point2, point1]

/Nicklas

2009-06-23 Caspa wrote:

yeah this could be the solution...unfortunately I have postgis version 1.3.5 and i doesn't have this feature yet..(I'm on debian system and don't want to build from source)
>
>
>>SELECT ST_MakePoly(ST_>

>LineFromMultiPoint(ST_collect(coord1, coord2, coord3, coord4, coord5, coord1 ))) from table

>this doesn't work, but I'm trying to use LineFromMultiPoint in other ways...maybe it works...
>
>THANKS
>
>SELECT ST_MakePoly(ST_>

LineFromMultiPoint(ST_collect(coord1, coord2, coord3, coord4, coord5, coord1 ))) from table
>
>

2009/6/23 <nicklas.aven@...>
> >

About st_makeline an array is needed like this example:

select st_makepolygon(ST_MakeLine(array[st_point(3, 2),st_point(2, 2),st_point(3, 3),st_point(2, 5),st_point(5, 5),st_point(3, 2)]));

greetings

Nicklas>

>
> 2009-06-23 Caspa wrote:
>
> 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
> >
> >postgis.refractions.net/documentation/manual-svn/ST_MakeLine.html
> >
> >postgis.refractions.net/documentation/manual-svn/ST_BuildArea.html
> >
> >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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> >

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