3D Filtering (Areal Filtering)
Short Wavelength Pass Filter - L-Filter
The L-Filter is used to attenuate the longer spatial wavelength structures that may be present in the measured surface, which are not relevant to the attended application and may affect subsequent analyses. The figure below demonstrates an L-Filter used to remove the longer spaced spatial structure revealing the finer spaced texture and peaked features.
When only an L-filter is used, the type of filtering is termed Short Wavelength Pass.