As we read before in the Introduction, collaboration is a recursive and iterative process with the purpose of solving a problem or a situation in a systematic way (Dictionary 2007). It implies two or more individuals or organizations involvement in a mutually interested common goal. This process is creative in nature and its results are dependent on knowledge sharing, on learning from each team member and on building consensus towards a commonly recognized solution. Because humans are essentially different, the tendency is to form strong believes based not only on objective facts, but also subjective. Thus leadership is required, allowing all participants to express themselves and keep also the entire process focused on a specific path towards the goal. (Hilliges und al. 2007)

The collaboration process is also based on the fact that one people might not have the entire knowledge base required to solve a complex problem. Additionally, because each individual has a different understanding of the information, the knowledge might be distributed and sometimes controversial. There is a “Symmetry of Ignorance” (Fischer 2000) defined, in which different people are collaborating together, each one having different background and knowledge. They complete each other, learning and teaching, presenting the situation perceived through their different viewpoints, discovering alternatives or subtle problems of others’ proposed approach.

The basic requirement a system has to fulfill in order to be considered as supporting the brainstorming process is to allow the registration of ideas and their display in one place. This is a very basic purpose, as even a pen and pieces of papers can fulfill it. Yet without it we cannot conceive the support for a brainstorming session.

A second requirement to be fulfilled by a system in order to be considered is to use the Natural User Interface paradigm, as this is the subject of interest.

All other features which affect the level of system’s usability are considered additional.

Deriving from the research questions and from the interest of the thesis, a framework for analysis has been developed. The framework will be used to evaluate the brainstorming applications and to investigate their solution to the research problems. The properties of the framework can be divided into five categories.

1. Additional features that the present thesis investigates are related to manipulation of ideas and brainstorming sessions, features which have an impact on the usability of any system supporting brainstorming:
• The ability to organize ideas into groups or categories;
• The possibility to create relationships between ideas, linking them into logical constructions;
• Saving the session is an important feature, as it allows the results to be persisted over the time;
• Resuming the session is also important, allowing other teams to further continue and improve the brainstorming session result.
2. The interactivity would benefit from using natural gestures, allowing the participants to focus more on ideas and less on the tools to input them into the system  (Billinghurst 2008). Additionally, it would be interesting to know what input devices / mechanisms are available and in what degree the users prefer to use each of them.
3. To answer the research question regarding the way to support the brainstorming process the framework proposes to investigate the mechanisms used by the related systems to help the brainstorming session and the idea generation;
4. It is interesting to study if the brainstorming session is used by other applications. Hence, the thesis will look for the integration of the related applications with other system as a baseline;
5. One other research question the thesis must answer is about the mechanisms to  address the physical limitation of the tabletop. Therefore, the framework will investigate how do other brainstorming applications address the scenario when too many people join the session to be able to position themselves around a physically limited tabletop.

The research on collaboration using tabletops is quite extensive for how few actual commercial devices exist, but nonetheless it shows the potential in this area. A matrix with the features provided by each system is presented below in Table 1 – Matrix of the features employed by the related systems.

Table 1 – Matrix of the features employed by the related systems

Analyzing the above table, an interesting result arises. Almost all application have the basic properties of organizing and relating ideas. On the other hand almost none of them helps the brainstorming session and don’t address the physical limitations of the tabletop. Additionally, only one of them allows the result of the brainstorming session to be reused in another application.

As we can see, none of the already presented systems meet all requirements. Thus, I will introduce a concept for new application – Brainstorming activity support on multitouch and multiuser devices.