another multi-touch concept..

Just thought I'd share another idea using the FTIR multi-touch technology: the multi-touch touchpad/mouse. Basically it works the same as touchpads on laptops do. I imagine that it is fairly small, maybe 4-5 inches square. You can make little sweeping motions to move the mouse cursor around as with touchpads, but you can also touch with multiple figers in order to produce scaling and rotational information. Basically instead of just producing 2d movement information (as a regular touchpad) it would produce a transformation matrix containing translation, scale and rotational information. You could even scale along an axis by touching with 3 fingers and keeping one stationary while moving the other two. It would be easier to construct and have a smaller (portable) form factor. You don't need a projector. You could probably construct it using a webcam fairly close to the acrylic - maybe a fisheye lense would help. So many applications feature transformation (move/rotate/scale) - 3d modelling aps, 2d vector art apps, paint apps, music apps, etc. It might be a really nice, intuitive input device.