Together with colleagues Peter Bomark, Dr. Johannes Hirche and Tim Roth (website) we have been working on a Diffused Illumination setup. We use 4 illuminators, frostened lee filter on the inside of the box, a 3m 700 DMS projector, lee filter as a diffuser and an unibrain cam.
Other then that I think my personal preference goes out to FTIR, because it's more robust especially in different light environments, even though you can use fidicuals with DI, it's less robust, because of inputs that you might generate with for example your wrist.
With our FTIR setup I can generate inputs by blowing hard from very close. So I hardly have to touch the surface with my fingers, very smooth. Other then that it's easier to use for example brushes and pen alike materials.
I'll be posting video's later on.