Areal method
Areal method glossary
Scale limited surface
The surface data are serving as the basis for the calculation of areal surface texture parameters. S-F surface or S-L surface. Sometimes simply referred to as ‘surface.’
Areal filter
The filter for the separation of the long and short wave components contained in the scale-limited surfaces. Three types of filters are defined according to function:
- S filter: Filter eliminates small wavelength components from scale-limited surfaces
- L filter: Filter eliminates large wavelength components from scale-limited surfaces
- F operation: Association or filter for the elimination of specific forms (spheres, cylinders, etc.)
NOTE: Gaussian filters are generally applied as S and L filters, and the total least square association is applied for the F operation.
Gaussian filter
A type of areal filter normally used in areal measurement. Filtration is applied by convolution based on weighting functions derived from a Gaussian function. The value of the nesting index is the wavelength of a sinusoidal profile for which 50% of the amplitude is transmitted.
Spline filter
A type of areal filter with smaller distortion in the peripheral edge when compared to the Gaussian filter.
Nesting index
The index representing the threshold wavelength for areal filters. The nesting index for the application of areal Gaussian filters are designated in terms of units of length and equivalent to the cutoff value in the profile method.
S-F surface
The surface obtained by eliminating small wavelength components using the S filter and then processed by removing certain form components using the F operation.
S-L surface
The surface obtained by eliminating small wavelength components using the S filter and then eliminating large wavelength components using L filtration.
Evaluation area
A rectangular portion of the surface designated for characteristic evaluation. The evaluation area shall be a square (if not otherwise specified).
