Hotel group Marriott is set to project ads into the night sky using a new technology — but the public won't be directly looking at them.
Using a technique called persistence of vision, the ads will be seen for between a tenth and a quarter of a second, but only when the viewer moves his or her head.
Marriott's ads will show the Eiffel Tower and the Colosseum in Rome projected across London's River Thames for three days from Thursday afternoon, as part of its Travel Brilliantly campaign, it said in an emailed statement.
"While viewers are given the impression that the dramatic images are projected into the night sky, they are in fact 'printed' temporarily and safely onto the viewer's eye using the persistence of vision effect," the statement added.
Outdoor ad agency Kinetic worked with technology company Lightvert on the campaign and Marriott said it's the first time the tech — called ECHO — has been used commercially.