[postgis-users] N-Point Buffer

[strk at refractions.net]

On Wed, Dec 21, 2005 at 11:58:09AM +0100, Stefano B. wrote:
> thanks
> 
> but the function azimuth is only on cvs 1.1 version?
> and where is the online documentation?
> It seems that the documentation link is wrong (on postgis site). If I try to
> get the online documentation the link give me the pdf documentation file (I
> think this file is older that the online docs).
> 
> I ask this questions because I don't know how to use the azimuth function. I
> see on the web something like
> azimuth(Geometry,Geometry)
> 
> You said me:
> 
> > 2) Order points by azimuth from [C] (Azimuth)
> 
> but I don't undestand how to use the azimuth function in order to to this.
> (perhaps have I to insert the points in the first parameter and the centroid
> in the second one?)

Yes, but thinking better about this it won't really guarantee a
valid (non self-intersecting) ring in output, anyway :(

Your goal is build a valid Line using MakeLine.
The hard thing is find a correct order for the points.

meanwhile... a very simple thing just came to my mind.
ConvexHull! This is the one, sorry for prior confusion ;)

	Buffer(ConvexHull(Collect(points))) 

--strk;