View compliant surface
The compliant surface overlay is used to describe an overlay placed above the acrylic. The compliant surface overlay needs to be made of a material that will “couple” with the acrylic surface under pressure and set off the FTIR effect, and then “uncouple” once the pressure is released.
The compliant surface overlay can also be used as a projection screen.
Rosco Grey, as described in Jeff Han’s paper is a very poor compliant surface overlay despite the fact that it’s a good stand alone projection screen.
The Rosco Grey rear projection screen can be placed beneath the acrylic as well, as a diffuser, but the blobs that are detected by the camera get more blurry/less sharp.
Advantages of a compliant surface are:
1) Protects the expensive acrylic from scratches
2) Blocks a lot of light pollution.
3) Provides consistent results (the effectiveness of the bare acrylic touch seems to be down to how sweaty/greasy yours hands are).
4) Zero visual disparity between the touch surface and the projection surface
5) Pressure sensitive
6) Seems to react better for dragging movements (at least in my experience)
7) Brighter blobs to track, as there is no longer a diffuser between the IR blob light and the camera.
Recommanded surfaces:
Currently the hunt is on to find a compliant surface overlay that works as both a projection surface as well as a touch surface.
Users have been experimenting with various rubber materials like silicone.
