Reality touchscreen University of Groningen
“This is the curved screen in our reality center of the University of Groningen. We just finished building our own touch detection for it.
We used six Optitrack v120 slim camera’s which have a good sensitivity for infrared light. We used 16 cheap infrared emitters (the kind used for security systems) with a total of 1000 LED’s.
The touch detection software runs on three old computers each with two camera’s connected. One extra computer combines the output from the detection computers and send event data to our main visualization system.
This way we have (even using the old computers) enough processing power to be able to run the detection software at 60Hz and with a latency between 30 ms and 50 ms. It can detect without any problem 100 different touches at any time (more is possible, but it becomes slower)
We used a modified version of Community Core Vision (CCV) 1.4 (nuigroup.com) (modified so it can do two camera’s on one computer).
The communication protocol is preferable TUIO (tuio.org) and we did install Multi-touch Vista (multitouchvista.codeplex.com), which translates TUIO events to WM_TOUCH events for windows 7.
The demos you see in the video are from Multitouch for Java(tm) MT4J (mt4j.org/mediawiki/index.php/Main_Page). The part where the wizards are throwing fireballs at each other is using msafluid (project home is at msavisuals.com/msafluid ).
The curved screen itself is consist of a 3 mm dark acrylic layer, coated with a diffuser on the front. Illumination is from behind using six full hd Barco projectors.
The cameras and the ir-leds are also located behind the screen.”