In this paper, the authors classify sites related to the collection of VGI in order to study VGI quality and develop methods for analyzing VGI. VGI has altered how spatial data are created and the mechanisms for using and sharing these data. Because VGI is driven by contributors’ collective efforts, I am curious to know what motivates individuals to give freely of their time and expertise to develop VGI? What makes contributors stop contributing information to VGI projects? How do their motivations change as they engage in VGI activities? Will individuals map an area that has already been mapped in the last few years?
The authors point out concerns over the quality and trustworthiness of VGI. As we know, VGI has been used as an alternative to commercial or proprietary datasets. This makes me wonder about how can a VGI project, with no strict data specification or quality control, establish some type of trust. How to measure the reputation of a contributor to provide a better understanding of the quality and trust of the data? How to assess the quality of the contributions? Last, the authors mention that “VGI has the potential to address and constraints and omissions that plague SDIs”. Although VGI has concerns about data quality and scale and will not completely replace SDIs, I believe that VGI will become a key spatial data producer in SDIs.