[postgis-users] Closest point on a POLYGON to a given POINT

[strk]

On Mon, Oct 12, 2009 at 04:43:39PM +0200, Juergen Lorenz Simon wrote:
> Hi,
> 
> I have a nut to crack and i'm not finding anything suitable in the  
> PostGIS documentation. The problem is as follows:
> 
> I have a POLYGON G and a POINT P. I'd like to find the closest point  
> to P on G (not in, ON). Is there a quick way of doing this with the  
> build-in functions? Or is there some plsql routine I can use?

Try with ST_Line_Locate_Point [1] against the polygon boundary
(I'm assuming you mean ON as in "on boundary").

It'll take some looping and distance comparison if your polygon
has holes.

[1] http://postgis.refractions.net/documentation/manual-svn/ST_Line_Locate_Point.html

--strk;

 Free GIS & Flash consultant/developer      ()  ASCII Ribbon Campaign
 http://foo.keybit.net/~strk/services.html  /\  Keep it simple!