1

I am working within a local city government on creating a routing network and started last week with little to no knowledge of pgRouting. I want the routing network to be used by our fire department and public schools. A series of travel-time buffers radiating from each fire-station is my goal. Example: how far can we travel in 1 min? 5min? 10min? from each station.

I found what visual I am looking for via:https://anitagraser.com/2011/02/12/drive-time-isochrones/

So far I have successfully created a database for the routing, created both extensions (PostGIS & pgRouting), imported my shapefile road centerlines successfully into my database, and lastly I ran pgr_createtopology. The results are great! My pgRouting plugin within QGIS works flawlessly. The next step is where I need help!

Should I create nodes? Or, alternatively, can I just use the vertices from the ""_vertices_pgr table generated from function: pgr_createTopology?

The ""_vertices_pgr table contains an "id" column but I can't see any column with any geographic data within the table. Is this why we can't use the vertices table? Is there something I am misunderstanding about creating a node network when I already have vertices created from pgr_createTopology?

  • The vertices table does have a point geometry column (the_geom). The id column is referenced by the target or source column in the original segments table. If you don't have a geometry column in the vertices table, something has gone wrong. – Rob Skelly Jun 28 '17 at 20:48
3

For shortest path Dijkstra or driving distance queries you only need a valid network topology with source and target attributes in the network table.

The _vertices_pgr table is generated when you run pgr_createTopology function or when you use osm2pgrouting. It can be convenient later, for example when you want to link the node geometries with the result of your drivetime query. `

In case you want to recreate the vertices table, you can use pgr_createVerticesTable function.

The id column in the vertices table can be linked with the source and tatget coulmn of the network table.

| improve this answer | |

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.