Sorry it's a trade secret ! only kidding! It's actually both, I made the details as a mesh but it was so detailed it kept crashing my Poser & Bryce! So after some good advice from renderosity members I smoothed out the mesh and created the Illusion with both a texturemap & a bumpmap so it went from 89,000 kb or larger to the fixed file that looked as good at a smaller 4,442kb .