Extraction of places related to Flickr tags

Geographic information systems use databases to map keywords to places. These databases are currently most often created by using a top-down approach based on the geographic definitions. However, there is a problem with this approach in that these databases only contain location definitions such as addresses and place names, which does not allow for searches using keywords other than these words. Additionally, they do not give any information on the popularity, e.g., which is more popular among the places indexed by the same keyword. A bottom-up approach, based on the actual usage of words, can address these problems. We propose a method to aggregate tagging data and extract places related to a tag using the pair of a tag and a geo-tagged photo. We target the co-occurrence of a tag and the geolocation and represent the places related to a tag as a probability distribution over the longitudes and latitudes. We applied our method to data on the photo sharing service Flickr and experimentally confirmed that our method made it possible to highly-accurately extract places related to tags. Our direct bottom-up approach enables the extraction of place information that is not obtained by using traditional top-down approaches.