Geo-location inference from image content and user tags

Associating image content with their geographic locations has been increasingly pursued in the computer vision community in recent years. In a recent work, large collections of geotagged images were found to be helpful in estimating geo-locations of query images by simple visual nearest-neighbors search. In this paper, we leverage user tags along with image content to infer the geo-location. Our model builds upon the fact that the visual content and user tags of pictures can provide significant hints about their geo-locations. Using a large collection of over a million geotagged photographs, we build location probability maps of user tags over the entire globe. These maps reflect the picture-taking and tagging behaviors of thousands of users from all over the world, and reveal interesting tag map patterns. Visual content matching is performed using multiple feature descriptors including tiny images, color histograms, GIST features, and bags of textons. The combination of visual content matching and local tag probability maps forms a strong geo-inference engine. Large-scale experiments have shown significant improvements over pure visual content-based geo-location inference.