[postgis-users] postgis topology strange behavior

[Sandro Santilli]

On Mon, Feb 24, 2014 at 12:01:28PM +0000, Gonçalo Revez wrote:
> Hello,
> 
> I'm using the postgis topology with the following example below.
> 
> It inserts three contiguous polygons, but the third has a strange behavior.
> 
> It seems that the polygon doesn't snap totally to the other polygon (with
> model tolerance of 0.1), where he should split the edges and create a node.
> 
> The problem raises two edges "overlapped". (I attach an image showing the
> topology error).

Does ValidateTopology catches that error ?

> In fact, using the jts viewer, the third polygon overlaps the first
> polygon, but below the topology model tolerance.

In the topology primitives tables there are no polygons, the errors
you're after are overlapping or crossing edges, can you find them ?

> How is it possible to solve this type of situation or what could be the
> error in example?

Can it be you're referring to TopoGeometry overlap ?
Those ones are not errors, but perfectly leagal situations.
You can find them by counting the number of TopoGeometry objects
each topolgy face primitive contributes to.
Faces with count > 1 are overlaps, faces with count < 1 are "gaps".

--strk;