在Android上创建和显示室内地图

I'm developing an Android application and I would like to display an internal (indoor) map of some buildings, but I don't know where to begin: I want to create a custom kml file (how it's possible to create it? with which tool?) and display it in a fragment. I already have it working with external maps (simple GoogleMap in MapFragment), so it would be super to have the kml file placed 'over' the GoogleMap, like real indoor maps.I'm developing an Android application and I wou