Dr. Sassi,
I found a great tutorial teaching about using alpha to show displacement in certain areas. Learned a lot from it. I decided I wanted to give it a go and what I want is to have clones of an object i model to show only in the alpha areas. So in my scene file I made a sphere and I have a head bust. Both have the same materials. the base to show whatever color. the second is the blue color with alpha out areas. I then made a cloner with object mode and dropped in the objects. Used a shader material and copied the alpha channel from the material. If you look at the scene file you will see the clones are not following correctly at all. I cannot figure this one out! anyone have any ideas?