Standard tile layer
| Standard style layer|
or OpenStreetMap Carto
|Author||Andy Allan and other contributors|
|Tiles License||CC-BY-SA 2.0|
|Style License||CC0 1.0|
The stylesheet is maintained at https://github.com/gravitystorm/openstreetmap-carto. Bug reports (e.g. rendering problems of specific object classes) can be raised there (needs a login with a GitHub account).
OSM servers deployment
Low and medium zoom tiles (z0-z12) are usually re-rendered only when new osm-carto version is being deployed. Database schema change should not be requested more often than 1-2 times a year (probably combined with major PostgreSQL release).
If using the Standard tiles from openstreetmap.org tile servers in other applications, you must follow the Tile usage policy.
The style is designed as a general purpose map of the world, so for example:
- special objects (like seamarks or railway details) will not be rendered
- labels are rendered with a name=* value (whatever it contains for a given object), so it's not displaying English names all over the world
- there are no country specific symbols (like for example road shields or subway/metro signs), they all have a uniform look
While osm-carto tries to show many different objects, it's not possible to render everything stored in a database, so opt-in selection is made.
Mapnik and CartoCSS
openstreetmap-carto tiles are rendered using the Mapnik toolkit. That being said, openstreetmap-carto and Mapnik are not the same thing! Mapnik is a map rendering library used for many map stylesheets (including openstreetmap-carto).
CartoCSS is used to pre-process the stylesheet into Mapnik XML format (since August 2013).
This style has multiple layers. For example names of waterways are rendered over waterways, shops are rendered over buildings, tunnels are rendered over buildings, roads are rendered over landcover etc.
The remaining question is how objects are rendered within layer. For some cases collisions are not allowed and objects that would cover already rendered object from given layer is not rendered. It is done for example for cities, where labels for smaller that would collide with label for larger one are not rendered.
Landcover areas are ordered by area, with smaller ones later and collisions are allowed. It means that for a given layer smaller areas will cover larger.
For example small leisure=park area will be rendered over larger landuse=residential area.
There is also a separate overlay layer containing for example tree symbols for forest landcover, that is rendered over landcover fill.
- area covered by small landuse=forest and large landuse=residential
- forest fill will be rendered over residential fill and cover it, later forest overlay will be rendered over that
- area covered by large landuse=forest and small landuse=residential
- residential fill will be rendered over forest fill and cover it, later forest overlay will be rendered over that
General project configuration is included in project.mml (YAML). There are defined so called "layers", which include mainly SQL statements selecting the objects, while actual styling is done in multiple *.mss files. All the icons are pixel-aligned vector images (SVG). Some patterns are also done this way, but if they are still raster images (PNG), they are derived from vector elements and the process is documented, so it should be easy to migrate to a vector format when possible.
Roads code is very complex and is partially generated by the helper scripts.
Noto font is used if possible, with DejaVu Sans, Hanazono and Unifont used as fallbacks.
The style relies partly on some external data files coming from Natural Earth and preprocessed OSM data repository OpenStreetMapData. They can be updated with a Python script (scripts/get-shapefiles.py) or by hand.
Rendering coastline on openstreetmap.org is described here: Coastline#Rendering_in_Standard_tile_layer_on_openstreetmap.org.
Contributing and installing
You can set up a copy of the openstreetmap-carto rendering stylesheets for yourself. For more technical information, including setup instructions, see https://github.com/gravitystorm/openstreetmap-carto on GitHub. Contribution guidelines are documented here. One can set a simple Docker-based environment for testing. Some easy tasks has been selected for getting started with the process.
Standard osm-carto style is used as a base for some forks, especially:
- German osm-carto style (does also contain a branch with a localized version of Standard tile layer)
- French osm-carto style
- British osm-carto style (AJT)
- osm-carto vector-tiles
- OpenStreetMap Carto Tutorials
- Timelapse videos of changes in osm-carto 2012-2016