Database Reference
In-Depth Information
'the_geom_topo','MULTIPOLYGON') As
layer_id;
postgis_cookbook=# INSERT INTO
chp03.hu_topo_polygons(name_1,
the_geom_topo)
SELECT name_1,
toTopoGeom(the_geom, 'hu_topo', 1)
FROM chp03.hungary;
13. Now, if you check the information related to the topology using the
topo-
logysummary
function as follows, you can see that there is one face per
administrativeboundaryandtheprevious77facesgeneratedbytopological
anomalies have been eliminated:
postgis_cookbook=# SELECT
topologysummary('hu_topo');
topologysummary
--------------------------------------------------------
Topology hu_topo (2), SRID 3857,
precision 1 +
52 nodes, 70 edges, 20 faces, 20
topogeoms in 1 layers+
Layer 1, type Polygonal (3), 20
topogeoms +
Deploy:
chp03.hu_topo_polygons.the_geom_topo
+
(1 row)
14. Finally,simplifythepolgyonsofthe
topo_polygons
tableusingatolerance
of 500 meters, as follows:
postgis_cookbook=# SELECT
ST_ChangeEdgeGeom('hu_topo',edge_id,
ST_SimplifyPreserveTopology(geom, 500))
FROM hu_topo.edge;
15. Now, it's time to update the original
hungary
table using a join with the
hu_topo_polygons
table by running the following commands:
