413359 (1) [Avatar] Offline
#1
Hello,
I have been following the chapter 13 to convert an ITN file of the road network of UK, coming in gml2 format, to topology. I am still trying to understand the underlying logic of the topology, so my question might be related to the fact that I still don't understand it.
I first imported the geometry with ogr2ogr. This created a table 'holloway_itn.roadlink', with the geometry of the road network as LINESTRING.
I am after the faces that the topology layer, as I understand, is supposed to create.

I created the topology schema:
SELECT CreateTopology('holloway_itn_topology', 27700, 0.05);
And then add the topogeometry column:
SELECT
ogc_fid,
TopoGeo_AddLineString(
'holloway_itn_topology', wkb_geometry
) As edge_id
FROM (
SELECT ogc_fid, wkb_geometry FROM holloway_itn.roadlink
) As f;

This creates nodes and edges that show correctly when imported in QGIS.
The faces show up only as external bounding box but there is no sign of the polygons within the network.

Is there something I am doing wrong? Do you know a possible cause of this behaviour?

Thank you,
Duccio
422426 (1) [Avatar] Offline
#2
Para acceder a la geometria debe usar la funcion ST_GetFaceGeometry
Saludos
M.