you could try this one
http://www.myfonts.com/fonts/mostardesign/interval-sans-pro/

and to be honest, from the skew of the shot it can be hard to be certain. the designer of Open Sans states it's a Humanist font, and they all look quite similar. i'd guess it may just depend on some very tiny detail that may not be apparent with the letters in your sample, or a weight needed that is available in one font but not another.

in specific, the lowercase r may be a telltale character, or perhaps the roundness of the bowl in the d.