"I Was Here": Enabling Tourists to Leave Digital Graffiti or Marks on Historic Landmarks

Since ancient times travellers and tourists were carving or writing their names and messages on historic landmarks. This behaviour has prevailed to this day as tourists try to leave their marks at places they visit. Such behaviour, today often seen as vandalism, is particularly problematic since the society tries to preserve historic landmarks while graffiti often leave indelible markings. One solution to this problem is to allow tourists to write digital graffiti projected on historic landmarks and other public surfaces as an additional tourist offer. Projecting digital information on walls does not leave permanent marks while still allows authors to “physically” mark the place they visited. In this paper we frame our vision and highlight the approach we plan to pursue within the context of this topic.