The more detailed zoom levels were exported pixel by pixel from the DCS game world with a Lua script (I found no way to get at the vector data).
If you have any questions or suggestions, PM me ([FSF]Ian) on the ED forums.
Known Issues
This map uses a beta version of OpenLayers 3, which does not seem to work correctly in Google Chrome.
At least on my machine, it will stop loading map tiles after a while when using Chrome. I recommend using a current version of Firefox or Internet Explorer for now. Also, zooming out all the way can cause some browsers to freeze for some reason.