Web 2.0 geotagged photos: Assessing the spatial dimension of the phenomenon

Among popular Web 2.0 applications are the social networking, photo-sharing websites like Flickr, Panoramio, Picasa Web, and Geograph. The phenomenon of user-generated content and the increased presence of geographic information in such applications have motivated researchers to consider them as a source of geographic information. In this paper we question whether such web applications can serve as reliable sources of spatial content. We differentiate between spatially explicit and implicit applications, in accordance to their declared aims, and evaluate if they have an impact on the spatial distribution of geotagged photos for Great Britain. We also compare the spatial distribution of the photos submitted with population data, and the patterns of contribution to these sources over a period of 18 months. Finally, at a larger scale, we examine the spatial distribution of photos and their spatial density for 15 test areas and look into issues such as data currency and user behaviour. Our findings show that only web applications that urge users to interact directly with spatial entities can serve as reliable, universal sources of spatial content.