I've been thinking about 3D movement on iPads, in relation to a game idea.
What I'm sure of -- after trying a few -- is that invisible sliders and joypads *really don't work*. You can't see them, you can't feel them, and therefore you lose them. Visible sliders and joypads are nearly as bad, because you're looking at the scenery rather than the controls.
What I've come up with (not yet tested) is quite similar to this, actually. I don't think putting your hand in front of the screen is a big deal. I have several touchscreen-toys where your hand is constantly on the screen; you wind up unconsciously shifting it out of the way of whatever you want to see.
My slightly different idea is "one finger to turn, two fingers to walk." That way you can walk forward by keeping two fingers near the *bottom* of the screen, which reduces the obstruction even more. But, as I said, I haven't tested it yet. One of these weekends I'll fire up Unity and give it a try.
_________________
Andrew Plotkin (KI#00102725)
Uru Newcomer's Guide and Answer Sheet
-- http://eblong.com/zarf/uru/newfaq.html