I don't know i've done some tilling models.
Imported them and "glued" them by code to be as precise as possible, i tried simple lightening possibilities:
-sun
-ambient
-shader
Each time i had visible seams caus of vertex that didn't have same color between the models due to lightening !
If someone can tell me how to do like in that demo or if someone have some little code or demo, i'm very interested indeed

(I planned some tilling level editor (even sharing it with community or making some Game tilling template, but i abandonned due to that problems).