Ok, the process of generating the world from the 'macro' map is on its way. Here is a example.
This is the macro map with the player position in white, on the east coast of the island.
Now a part of the real size map generated for this single pixel :
The real map interpolates the terrain type for the current region and the neighbour regions, then adds a perlin noise to increase the level of detail. For now, the whole world terrain is generated from a single 32 bit random seed.