Citizens as Earth observation sources : a workflow for volunteered geographic information sensing

This research introduces the notion of Volunteered Information Sensing (VGI Sensing) as the set of standards, methods and techniques required to streamline georeferenced contents published online by citizens into a timely, reliable and cost-effective source of Geoinformation for Earth Observation purposes. VGI Sensing is proposed as an emerging sub-field of research at the conjunction of Geographic Information Science, Data Mining and (Web) Knowledge Discovery. It is expected to have many practical applications requiring pervasive and/or real-time geospatial data such as health epidemics, crisis management, environmental monitoring, crime analysis, or socio-economic studies. After presenting background works and formulating research objectives in the Introduction, this thesis explores the information potential of VGI (Chapter 1) in the context of natural hazards management, then proposes a generic workflow for VGI Sensing (Chapter 2) – which is exemplified to a real-life use case. Technical optimisations of key steps of the VGI Sensing workflow are then studied in details (Chapter 3), and finally, the concept of VGI Sensing is presented in the wider perspective of the Digital Earth Nervous System (Chapter 4). By doing so, it gives significant contribution to the sub-field of Geomatics that aims at converting information shared on the Internet by citizens as a reliable source of Earth Observation data, and opens perspectives for further research - which are discussed in the final chapter. An additional commentary is then proposed, addressing the questions related to the limitations and ethics of VGI Sensing.