The question: “What is a tile server good for, why is it needed?“ often arises.
What are “Tiles”?
Most web-maps work this way: You have a nice coloured map and some markers on them. You can think of it as an endless sheet of paper with POIs marked with pins, where the “viewing window” can be moved endless in any direction (since we live on a sphere and not on the Discworld). It is often called Slippy Map.
- The markers are the data you want to display, e.g. TransforMap initiatives.
- The underlying “nicely coloured map” is actually not an image with infinite size, but made of many smaller ones stitched together and loaded on demand, when panning.
These small images (Map Tiles) are made by a so called Tile Server. It converts vector data like streets and forest areas (in our case from OpenStreetMap data) into pixel graphics then delivered to the user’s web browser.
So when someone want to create a web map, a nice background map is needed. There are a lot of different tile servers with different styles available for use.
Data might be free, services are not
If someone wants to deploy maps at a bigger scale, one has to think of tiles like resources:
- The servers who generate the tiles have to be bought (money), hosted (space) and maintained (time) by somebody
- It costs computing power (electricity) to generate and update the tile images from raw data
- It costs harddisk space to store them
- It costs bandwidth (internet fees) to distribute the tiles to the users
For small and non-commercial projects, the OpenStreetMap foundation allows the use of their tile servers, according to the Tile Usage Policy. As OSM states: Our data is free. Our tile servers are not.
In contrast Google: their service maybe gratis, but its not free - as your website visitors are sold to Google.
So, where to get tiles if someone wants to deploy maps?
- If you don’t expect heavy traffic (e.g. website of single or local initiative), you can use OSM’s accordingly to the Tile Usage Policy. The OSM Foundation does NOT provide commercial contracts for use of their tileservers!
Another option is MapQuest Open.They have recently limited it to 15.000 tiles/month.
- Setting up you own Tileserver, see switch2osm.org/serving-tiles.
- Buying tiles-as-a-service at one of the commercial providers.
- A new option still to be discussed: Wikimedia Map Tiles!
If you want your own map style, you have the possibility to set up your own tile rendering server, or use services e.g. from MapBox, who offer really easy style-editors.
TransforMap and Tiles?
TransforMap currently does NOT run their own tileservers or have a contract with a commercial provider. The maps on demo.transformap.co currently use MapQuest Open, and as second option the OpenStreetMap tileservers. We don’t generate that much traffic at the moment that we have to use other services.
If someone wants to deploy a TransforMap-based map on their own website, you currently have to get your tileservers according to the list above. TransforMap cannot guarantee that OSM allows usage of their tiles on a heavy-traffic website!
If we should set-up tileservers for common use, we can do that if there is demand - if there is a way to get the needed resources.
If you want help setting up your own tileserver, contact us - e.g. @species can help.