Multimodal processing solutions use devices and sensors to capture different signals, and try to blend them together to provide extensions to the traditional man-machine interface.
Gestures, movements, speech and verbal and non-verbal expressions are all ways to express emotions and feelings. But understanding of emotions is a field apart:

• What if contradictory signals are detected?
• What if a person is not behaving naturally?
• What about emotions induced by a theatrical performance?
• What about an individual not exactly free to express itself because of some sort of pressure or disturbance in the space where he/she is immersed?

These are only a subset of the questions about understanding of emotions that require to move a step beyond simple signal detection and merge.
Let's go a bit further:

• How useful is it to perform emotion processing as a batch activity, if not for documentary purposes?

Reactive systems need to understand immediately the reaction of an audience to a plot if the storyteller has to change its narrative or if the user has to become part of it.

• To which extent can Augmented Reality contribute to enrich the experience?
• Which is the optimal boundary?
• Is interactive art a synonym of irreducible complexity?
•  How close are we to an acceptable blend?

And more.  Additional investigations are also challenging our project, to solve the dilemma of having artists engaged with IT specialists under the constraints of complex tools that limit their creativity or rather providing them with acceptably (simplest, not naive) solutions for the interpretation in human to computer interaction.

• Is the detection of basic Ekmanian emotions such as joy, fear or anger enough when the aesthetic properties of the media, or specific enjoyment and entertainment experience are an essential part of the dynamic of the emotion?

Those and similar research questions inspired the CALLAS project and our prototypes to progressively contribute to the advance of the state of the art in multimodal affective computing. The project is cultivating a community of amateurs, artists, technology providers and scientists, a dedicated social network (C³ : the CALLAS Community Club) through which accelerate the adoption of CALLAS and actuate its vision.