From a couple of answers at gis.stackexchange.com and at the pgRouting mailing list I have found out that pgRouting 'builds topology'. What does that mean?
If for example we import an .osm file into PostGIS and then apply all the pgRouting scripts, what does happen?
I thought that pgRouting just creates a table of road links (edges) from the OSM nodes, but after following the FOSS4G workshop I see the following tables in my database:
List of relations Schema | Name | Type | Owner --------+------------------+-------+---------- public | classes | table | postgres public | geometry_columns | table | postgres public | nodes | table | postgres public | spatial_ref_sys | table | postgres public | types | table | postgres public | vertices_tmp | table | postgres public | ways | table | postgres
I know what geometry_columns and spatial_ref_sys serve for, but what about the other tables and how do they relate to each other?
What is topology in pgRouting's parlance?