Thanks guys. TBH Lostclimate I just texture baked each part quickly so that I had some form of shading on each part so I could see it clearly for testing.

Once I have a good working map with these parts I can return to think about how the final parts will be exported. I did some earlier experiments with this method and had 2-3 parts with normal mapping and specular maps, which seemed to help the lighting issues, however its clear that the individual parts approach doesn't help the dynamic lighting system.

Hopefully I can get some parts with all the shaders working and see how the lighting looks. Right now its pretty ugly

Now that I have all the parts as models which I've now reduced to 16mx16mx6m as the original size was way too big, I should be able to creat a map that uses all the parts.

Each part has a 1024x1024 map assigned to give me an idea of how much memory this is going to use and then figure out a way to dynamically load the parts as the players move through...

I should be able to build a live 3x3 grid and load in the other parts as the player explores...so it should also give me the fog-of-war for parts that have not been explored yet.

As always I am getting ahead of myself...