Geo-Location Estimation of Flickr Images: Social Web Based Enrichment

Estimating the geographic location of images is a task which has received a lot of attention in recent years. Large numbers of items uploaded to Flickr do not contain GPS-based latitude/longitude coordinates, although it would be beneficial to obtain such geographic information for a wide variety of potential applications such as travelogues and visual place descriptions. While most works in this area consider an image’s textual meta-data to estimate its geo-location, we consider an additional textual dimension: the image owner’s traces on the social Web, in particular on the micro-blogging platform Twitter. We investigate the following question: does enriching an image’s available textual meta-data with a user’s tweets improve the accuracy of the geographic location estimation process? The results show that this is indeed the case; in an oracle setting, the median error in kilometres decreases by 87%, in the best automatic approach the median error decreases by 56%.