Geographic Location Tags on Digital Images

We describe an end-to-end system that capitalizes on geographic location tags for digital photographs. The World Wide Media eXchange (WWMX) database indexes large collections of image media by several pieces of metadata including timestamp, owner, and critically, location stamp. The location where a photo was shot is important because it says much about its semantic content, while being relatively easy to acquire, index, and search.The process of building, browsing, and writing applications for such a database raises issues that have heretofore been un- addressed in either the multimedia or the GIS community. This paper brings all of these issues together, explores different options, and offers novel solutions where necessary. Topics include acquisition of location tags for image media, data structures for location tags on photos, database optimization for location-tagged image media, and an intuitive UI for browsing a massive location-tagged image database. We end by describing an application built on top of the WWMX, a lightweight travelogue-authoring tool that automatically creates appropriate context maps for a slideshow of location-tagged photographs.