I can't get enough of these DIY multitouch projects, in fact I'm hoping that the more companies like Microsoft see that there's demand for large-scale, low-cost touchscreen technology, the more likely it is that they'll release products that the less DIY-able among us (myself included) can tackle. This latest, by Christopher Jette, outwardly resembles a rear-projection TV, but in actual fact it's a purpose-built multitouch displaythat uses the Frustrated Total Internal Reflection system to recognise multiple points of contact. As with many of the other projects, it relies on a hacked webcam, a standard projector and special software.
Check out the demo videos after the cut
Frustrated Total Internal Reflection uses IR leds to bounce light internally through a sheet of Plexiglass; normally the light is contained within the pane, but when a finger touches it's scattered out the back. That's picked up by the webcam, hacked to recognise only IR light, and the software translates those recognised blobs into stretch, twist and other commands. Christopher also adds a layer of silicone rubber which reduces the pressure needed against the screen.
Christopher is clear that this isn't really a first-time project, and nor is it suitable for commercial use. But his Instructable is certainly clear enough that if you're not as cack-handed as I am you could probably come up with a reasonable facsimile. I'm going to have to wait until Microsoft decides to stop being stupid and release their TouchWall software.
[via Hack A Day]