@conference { SBS13, title = {Assessing the credibility of VGI contributors based on metadata and reverse viewshed analysis - An experiment with geotagged Flickr images}, booktitle = {Proceedings of the 16th AGILE International Conference on Geographic Information Science}, year = {2013}, author = {Senaratne, Hansi and Broering, Arne and Schreck, Tobias} }