Schematic figure representing the shape of the Δ-variance spectrum for the THINGS galaxies. In some galaxies, some of the features of the spectrum such as the bump at small scales or the presence of two distinct power laws are not observed. The dashed line represents the extrapolation of the first power law down to smaller scales. The quantity represents the maximum deviation between the bump and the extrapolated power law. The value of L_sf represents the physical scale at which this maximum deviation occurs. As illustrated, this scales does not correspond to the peak of the bump and is generally smaller. The quantity L_tr is the physical scales at which a transition is observed between the first and second power law.