Towards Formal Measures of Usability for Visual Interactive Systems

Usability is the most important feature of a computer program from the users point of view. Even if various techniques for evaluating usability have been proposed, formal methods are still lacking. A good indication of program usability is given by the agreement between the mental model of the system, as conceived by the user, and the model of the user, as understood by the designer and implemented in the system. We extend here the visual sentence theory we have developed in the last few years by introducing the concept of relation system. This provides a means for describing both the user's and the program's models. Based on this formalism, we can also define some measurable properties for usability, and develop experimental protocols for their measurement

Net neutrality versus discrimination in internet access: Winners, losers and investment incentives

According to Neelie Kroes, the European Commission Responsible for the Digital Agenda, 'the internet is a great place to exercise and enjoy liberty'. To hold true this requires that users must be free of restrictions on their access to content and use of services. Thus, supporters of the principle of 'net neutrality' assert that internet service providers should be legally prevented from discriminating between different types of web traffic. On the other hand, some Internet Service Providers (ISPs) oppose net neutrality on the grounds that prioritisation of bandwidth is necessary for future innovation and investment. This paper provides constructive input to the debate on net neutrality by comparing the pay-off of internet service providers, content providers and users under the two opposing regimes of discrimination and net neutrality. In particular, through a game-theory model, we analyse gainers, losers and investment incentives in a duopolistic market, under the two scenarios

Gesture Based Interface for Crime Scene Analysis: a Proposal

Within crime scene analysis, a framework providing interactive visualization and gesture based manipulation of virtual objects, while still seeing the real environment, seems a useful approach for the interpretation of cues and for instructional purposes as well. This paper presents a framework providing a collection of techniques to enhance reliability, accuracy and overall effectiveness of gesture-based interaction, applied to an interactive interpretation and evaluation of a crime scene in an augmented reality environment. The interface layout is visualized via a stereoscopic see-through capable Head Mounted Display (HMD), projecting graphics in the central region of the user’s field of view, floating in a close-at-hand volume. The interaction paradigm concurrently exploits both hands to perform precise manipulation of 3D models of objects, eventually present on the crime scene, or even distance/angular measurements, allowing to formulate visual hypothesis with the lowest interaction effort. A real-time adaptation of interaction to the user’s needs is performed by monitoring hands and fingers’ dynamics, in order to allow both complex actions (like the above mentioned manipulation or measurement) and conventional keyboard- like operations