Talking about Places:Considering Context for the Geolocation of Images Extracted from Tweets. GI_Forum|GI_Forum 2018, Volume 1 |

This paper investigates the extraction of geolocated images from social media. Pictures taken with a mobile device are typically georeferenced, but social media may or may not provide geo-coordinates, depending on their privacy policies. Our goal is to geolocate images extracted from Twitter to support emergency services in natural disasters. As the number of tweets with native georeferences is limited, we introduce algorithms that take advantage of various contextual clues included in social media posts to help increase the proportion of posts that can be geolocated. Using an explorative approach, we also investigate how to locate, in other social media, images that were originally embedded in tweets. The application of these context-based algorithms to a case study is discussed