JRS at Event Synchronization Task

The event synchronisation task addresses the problem of aligning photo streams from different users temporally and identifying coherent events in the streams. In our approach, we first determine the visual similarity of image pairs. We determine visual similarity based on full matching of SIFT descriptors and based on VLAD, and compare the use of the two sets of similarity scores. We then build a nonhomogeneous linear equation system constraining the time offsets between the galleries based on these matching pairs and determine an approximate solution. Event clusters are initialised from subsequent and visually similar images, and clusters are merged if their temporal proximity and the maximum similarity of their members is high enough.