TUIO 2.0 specification nearing completionJanuary 4
It took longer than expected to develop the next generation TUIO 2.0 specification, since this new protocol generation is intended to cover a much wider scope of tangible user interfaces and interactive surface environments. The present TUIO 1.1 specification has been mainly used for multi-touch surfaces, but it also included the basic component descriptors for tagged and untagged physical objects.
In addition to improved multi-touch features, TUIO2 now has an even stronger focus on tangible (=physical) interfaces. Therefore it is not only enhancing the existing components with some previously missing attributes (e.g. pressure), but also defines new descriptors for additional interface component types. Apart from extending the existing descriptors for Tokens (tagged objects), Pointers (touch and pointing devices) and Bounds (untagged object geometry), TUIO2 introduces an additional Symbol component for the encoding of arbitrary symbols, such as RFID tags or data matrix codes. Additional Geometry messages now allow the more detailed description of the full shape of untagged physical objects, while several complementary Content messages allow the transmission of additional control dimensions, data content and signals for any interface component. TUIO2 also introduces the new category of Association messages, which allow to define various Container and Connection relationships between individual interface components. The new protocol finally also includes detailed Timing information, which is essential for the realization of gesture-based interfaces.
Due to its shared OSC name space /tuio2 and its more compact message syntax, the new protocol is hopefully more open for future extensions with additional component messages. This structure also allows the incremental description of individual interface components by a series of messages. A finger touch for example can now be encoded by combining a pointer and bounds message, while several properties of a tagged physical object can be referenced through a series of token, symbol and geometry messages.
Although the documentation still might need some improvements and eventually some minor error correction, I hope that the current specification actually meets its primary goals and can be soon declared final. If there are any objections or last minute proposals for improvement, please get in touch as soon as possible. In any case it will still take some more time before we are going to see actual implementations of TUIO 2.0, since most applications and client libraries are still in the process of implementing TUIO 1.1.