[postgis-users] Topology GetRingEdges

Bob Pawley rjpawley at shaw.ca
Mon Apr 30 08:30:56 PDT 2012

Well, it would seem to me that I need to identify the geometry at some point 
as a start (and end) for "walking" the geom, hence, the ST_Intersects.

I've attempted to use the geom column in the edge_data table but so far 
haven't been able to make this work (errors returned) -

select topology.getringedges(edge_data, 1), entities.wkb_geometry
    from "TEST".edge_data, entities
    where "TEST".edge_data.edge_id = 1

So far, this is the only combination that I can make work.

My problem may be that I am confused on the atopology varchar for which the 
GetRingEdge is looking, if it isn't the geom of table edge_data.

And I am also wondering why the TEST schema produced by toTopoGeom requires 
double quotes in order to be recognized?

Or am I entirely missing the point?


-----Original Message----- 
From: Sandro Santilli
Sent: Monday, April 30, 2012 2:51 AM
To: PostGIS Users Discussion
Subject: Re: [postgis-users] Topology GetRingEdges

On Fri, Apr 27, 2012 at 01:11:27PM -0700, Bob Pawley wrote:
> Hi
> I have established the schema and tables as outlined in the documentation 
> example 11.8 TopoGeometry Constructors.
> However, I am still missing something.
> When I run GetRingEdges -
>     select  topology.GetRingEdges('TEST', 1), entities.wkb_geometry
>     from entities, num_search
>     where st_intersects(entities.wkb_geometry, num_search.the_geom2);
> The return are only the geometries which are actually intersected by 
> st_intersects.(In this particular case only four of the eight lines that 
> make up the polygon).
> I was hoping the whole closed geometry  to be returned.
> What am I missing??

I don't understand what your query above is trying to select.
You are calling GetRingEdges with a constant edge id, why so ?


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