TUIO is a network protocol designed for transmitting MultiTouch input data. It is built on top of the Open Sound Control (OSC) protocol. TUIO is the de-facto standard for receiving information from MultiTouch tracking devices.
In general, a hardware device that supports TUIO has a driver or other piece of software that accepts an IP address and port the TUIO information should be sent to. If configured to the machine and port specified in the Ventuz Machine Configuration, Ventuz will interpret the raw touch information and send it to the various Interaction Nodes.
Ventuz does not offer any explicit TUIO Nodes as it does for OSC since there is great amount of calculation involved to transform the raw touch input into semantic information. Instead, the Ventuz Input Subsytem routs touch data directly to the interaction nodes such as the Touch Transformation Nodes. For more information, see MultiTouch.
TUIO defines a number of OSC messages to transmit touch information, of which Ventuz only supports 2Dcur (general touch) and 2Dobj (uniquely identified object, see Touch Marker). Each touch has a session ID that is used to identify a touch over successive frames. A MultiTouch hardware device usually sends a set of set messages to update the position of touches and an alive message that contains the session IDs of all touches still active. If a touch is set for an unknown session ID, the touch is new. If the alive message does not contain a session ID that had been used before, the touch has died. This design was chosen to prevent consistency problems if one of the OSC bundles is lost due to network problem.