Do you ask your players to have a sketch of their characters, and their equipment?

If so why, and if not why? I know that I often ask my players to have either a sketch or mini so the other players have a good idea what the members of their party look like.

I even went so far as to hand out extra Exp for Players who got themselves a decent picture and a coherrent background story in an attempt to immerse them a bit deeper in their character ... with varying succes

I think a good picture helps a great deal to get a first impression from the other PCs and a feel for the atmosphere of the game.