It looks like smoke billowing from a high-rise at first.

But look again - the surprising splash of gray against the blue Rio de Janeiro sky is a giant image of Sudanese high jumper Mohamed Younes Idriss making a larger-than-life leap over a 20-story building.

This Olympic-sized trompe l'oeil is the work of French art photographer JR, who is famous for plastering huge black-and-white photographs onto street scenes around the world.