Scanning technology for handwritten data has reached its momentum after the invention of the digital pen. Research work focused on the development of HMI applications that facilitate digital ink data manipulation. In a research context, digital pen and paper technology is useful for collecting experimental data in various fields. Our goal is to provide support for the processing and the visualization of time stamped data collected by a digital pen in two cases of use : on one hand, in the educational science field, and especially for assessment tests and, on another hand, for taking observation notes. Our approach is to study these cases of use through four concrete experiences and to develop, with the participation of the user, prototypes for a system that aid to process and to visualize collected data. In order to abstract a general model of such a system, we analyzed prototypes user interfaces in terms of functionality, visualization and interaction. Our model describes the visualization process by implementing three types of user tasks namely analytic tasks, handling tasks and interaction tasks.
