Planet PostgreSQL – Ryan Lambert: Routing through Lines and Polygons

One of my favorite layers to route with pgRouting is the water layer. I am interested
in where water comes from, where it goes, where runoff happens,
and how urban development interacts with this powerful force
of nature. The OpenStreetMap water layer, however,
presents a challenge when routing with PostGIS and pgRouting: Polygons.
Why are polygons a challenge? A routing network using pgRouting is built
from lines (edges).
Now, to state the obvious: polygons are not lines.
Real world waterway networks are made up of both lines and polygons.
Rivers, streams, and drainage routes are predominately (but not exclusively!)
mapped using lines. These lines feed into and out of ponds, lakes, and reservoirs. The following animation shows how much impact the water polygons
can have on a…

External feed Read More at the Source: https://postgr.es/p/5rb