Slippy map tile proxy server

Script to serve composite tiles and tiles from non-slippy-map servers, to programs that can only speak to slippy map servers

The tile proxy server solves me two issues I often experience with different programs that only support slippy map tile downloading from single sources:

1. Many nice online maps often use layers to display extra information, and programs that only support downloading single x/y/z tiles from a single server, cannot make use of the merged result (base layer with overlays). The tile proxy server can download multiple layers, make composite images on the fly, by downloading the base layer and any configured overlay, and serve back the merged result to programs that can't do that on their own.

2. Unfortunately, many servers often use different protocols (TMS, WMTS, WMS, etc) that are more complicated for me (and I guess for others too since many program don't support interaction with such servers) to understand. Regardless, I still want to interact with such servers from programs that only support the slippy map format. The tile proxy server offers a solution to this problem with the dynamic tile url generation functionality: your application still requests x/y/z tiles, and you can write a function in your map configuration to translate x/y/z to what a TMS/WMTS/WMS server can understand, fetch the tile, and serve it back to the program that only has slippy tile map support.

As I mentioned above, I don't understand much about TMS/WMTS servers, but the python mercantile and pyproj packages can make such conversions look simple.

See the sample norway_vfr map in the mainConf configuration, to see how you can use this feature. In the mainConf you can also look at the sample openflightmaps configuration that uses a base and an overlay to serve a merged composite tile.

Usage

1. Edit the mainConf dictionary in the slippy-tile-proxy-server.py file and add the map configuration that you would like the tile proxy server to serve (read the comments and have a look at the sample configurations that are included to understand how to add your configuration).
2. Save the script.
3. Run the script in a console: python3 slippy-tile-proxy-server.py
4. Make HTTP GET requests from your browser, or point any other program from your local computer to the url http://localhost:8080/map_identifier/z/x/y