Where have you been today? Annotating trajectories with DayTag

Traditionally, the information about human mobility behav- ior, called diary, is acquired from volunteers by means of paper-and- pencil surveys. These diaries, representing the mobile activities of indi- viduals, are semantically rich, but lack in spatial and temporal precision. An alternative way is collecting diaries by annotating with activities the GPS tracks of individuals. This is more accurate from a spatio-temporal point of view, but the manual annotation becomes a burdensome work for the user. The tool we propose, called DayTag, is designed as a per- sonal assistant to help an individual to reconstruct her/his diary from the GPS tracks collected by a smartphone. The user interacts through the software to visualize and annotate the trajectories, thus resulting in a simple way to get user diaries.