Filter Cutoff WavelengthThe filter cutoff wavelength describes the "amount of filtering" or the "location" of the filter's transmission characteristic in terms of a wavelength. In the typical analysis of roughness, a filter is applied with a cutoff at a user-specified wavelength. This wavelength distinguishes between roughness and waviness - wavelengths longer than the cutoff are considered to be associated with waviness. Similarly, wavelengths shorter than the cutoff are associated with roughness.The filter cutoff has a significant influence on the computed parameter values as the cutoff determines which profile features are included in a specific profile. In most cases, when nothing else is specified, a 0.8 mm cutoff roughness cutoff is appropriate. However, a better approach to cutoff selection has been outlined as follows: