This may be the last OpenStreetMap road query you will ever need.
Between Mapnik, Cascadenik, and Carto, you’ve got a few options for rendering OSM data to tiles. High Road makes it easier to draw the road bits by hiding complicated PostGIS queries behind views, so that you can declutter your layer names while ensuring that you’re using the right selection of roads for each zoom level.
There’s a sample Cascadenik style
and layer file, but the real
action is in views.pgsql,
where you’ll find a comprehensive set of Postgres views against the usual
table produced by Osm2pgsql.
To use High Road, run the source of
views.pgsql against your existing OSM rendering
database and check out the sample files to understand what each query is doing. I’ll
explain more here in the near future.
High Road is made by Michal Migurski, Nathaniel Kelso and Geraldine Sarmiento of Stamen Design.
Taking a cue from Justin O’Bierne’s dearly-departed 41Latitude blog, High Road ensures that each zoom level contains exactly three distinct levels of road: highways, major roads, and minor roads, a simplification of OpenStreetMap’s conventional six-level hierarchy.
At distant zoom levels, local and residential streets are omitted. Bold, simple highways dominate the map, and the visual layering is categorical to clearly separate each road type.
Deeper in to the map, local streets and highway ramps start to appear. You begin to see block-scale details:
At the closest zoom levels, physical layering takes over and you begin to see over- and underpasses as they exist in the built world:
A maze of ramps marks the east approach to New York’s Lincoln Tunnel:
A cloverleaf interchange on Moscow’s MKAD:
London’s dense network of trunk roads, centered on the Isle of Dogs: