Friday, April 17, 2009


The finished prototype (sans trace paper)

Here's a quick little project that I threw together with the help of Seth Sandler's MTmini (multitouch mini) guide. [link]

I've always been interested in touchscreen technology and this project was a good introduction into understanding basic touch screens. The MTmini pictured above is the prototype that I made in the hopes that I would be able to just get a feel for how to put together a better version. The prototype worked well enough (as did the software), although I used an almost completely unidentifiable webcam which (as I suspected) was very unreliable. It would work for a few minutes then just shut off, and I would have to unplug/plug it into the USB port a few times before it came back on.

Here's a picture of the sketchy webcam and its homemade poster board housing (...hey, it works).

In a nutshell, the MTmini works like this:
There's a box with a webcam at the bottom which is connected to a computer running Touchlib, an open source multitouch software (read more about it on the MTmini website, or the official site). The top of the box has a hard surface with something to diffuse light (such as tracing paper). Once the user touches the surface of the box, the shadow cast by their finger is processed by the multitouch software which is then translated into different actions on the computer like mouse clicks.

Despite the shortcomings of the webcam, my MTmini worked fairly well. The software came with a few demos, but I only had a chance to try one before the webcam shut off: the picture viewer. There were a bunch of preloaded pictures which could be enlarged, moved around, etc through the use of the MTmini.

All materials used:
  • poster board
  • cardboard box from Amazon package
  • duct tape
  • no, seriously, a lot of duct tape
  • clear plastic lid
  • tracing paper
  • webcam
If I come across a better quality webcam, I'll definitely give this project another look. It might be a fun programming project to make a mouse driver to represent holding down the mouse button for games like Crayon Physics Deluxe or Falling Sand Game.

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