3D Filtering (Areal Filtering)
Band Pass Filter
The combination of an S-filter and an L-Filter may be used to establish a bandwidth of spatial wavelengths which are used for analysis.
When the spatial wavelength of the structure to be analyzed is contained between the S-Filter cutoff and the L-filter cutoff, the filter is termed a Band Pass Filter.
The figure below demonstrates the use of a Band Pass Filter which is comprised of an S-Filter to remove short spatial wavelength structures and an L-Filter used to remove the longer spatial wavelength structures. The final surface consists of a band of spatial wavelengths relevant to the application.