The generalized Snell's law of refraction was introduce by F. Capasso in 2011. One consequence of the law is that resonant metallic nanostructures at the interface between two dielectrics can bent the light in a controlled way. Alternatively, by measuring the bent of a beam of light induced by a nanopatterned metallic surface it is possible to retrieve information on the surface morphology. Here we show that deviation measurements of the light passing through curved metallic nanowires deposited on a glass slide gives information on the morphology only when the resonance is excited.