Processing a plurality of media items that are associated with a respective plurality of locations includes: obtaining the plurality of media items; selecting a first media item that defines a first region on a map; determining a first set of media items that are located within the first region; selecting a second media item that defines a second region on the map, the second media item being selected among media items that are not located within the first region; determining a second set of media items that are located within the second region; and processing the first set of media items and the second set of media items as distinct groups.