[postgis-users] PostGIS Topology with Z coordinate

Berchet, Adrien adrien.berchet at forcity.com
Thu Jan 10 01:44:01 PST 2019

Thank you for your answer, I reply in the text body.

Le mer. 9 janv. 2019 à 17:44, Sandro Santilli <strk at kbt.io> a écrit :

> On Tue, Jan 08, 2019 at 01:00:54PM +0100, Berchet, Adrien wrote:
> > Hello,
> >
> > I am testing PostGIS Topology with 3D geometries and I am not sure of the
> > expected behaviour in this case. In the tests I conducted, it seems that
> > PostGIS Topo just ignores the Z components when searching for
> intersection
> > between geometries and thus creates some nodes where it is not needed. Is
> > it the normal behaviour please? Is it possible to build a real 3D
> topology
> > with PostGIS Topo?
> Real 3D is not currently supported by PostGIS Topology.

Ok, I missunderstood that point.
So is it possible to manage a kind of multilayer topology, to manage
bridges and tunnels in a network for exemple?

> I don't understand your statement about creating unneeded nodes
> though, do you mean multiple nodes with same x,y but different z
> are created ? Check out topology/test/regress/topo2.5d.sql if
> you want to add your case there and provide a complete scenario.

No, I meant that nodes are created even if the 'intersecting' lines have
different Z coordinates. It surprised me but you previously stated that it
is the expected behaviour. Thus the Z coordinate of a topology is only
intended to represent the relief of the topology, right?

> --strk;
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