As it is stated on Der Spiegel website, a British blogger Eliot Higgins localized an IS training camp.

Higgins found some photos of IS terrorists on their Twitter account, where 45 people wearing the similar clothes stand in front of a river. After doing just a little bit of research with Google Earth he found that it is Tigris River in Mosul, which is in the North of Iraq. Flash Earth service was used to localize some visible on the photos constructions.

Panoramio, which tags the location photographs where taken onto a map, helped to localize the training camp of terrorists.

Source: Bellingcat