Mean profile element spacing Rsm is the arithmetic mean of the profile element spacings Xsi of the roughness profile. A profile element is a hill followed by a dale or a dale followed by a hill.
The evaluation is thus performed in two directions. Generally, the thresholds to detect a profile element are 10% Rp and 10% Rv.
Root mean square gradient Rdq is the root mean square value of the local profile leads of the roughness profile.
The local profile leads are calculated using a smoothing function to suppress any noise influence.