DeFelsko PosiTector RTR 3D Mode D'emploi page 25

Gaussian filter attenuates features that have a longer wavelength than
the selected size.
The following Short Filters (λs) are available:
None
0.008mm
0.025mm (default)
0.080mm
The following Cutoff Filters (λc) are available:
None
0.08mm
0.25mm
0.8mm (default)
2.5mm
Discard
A side effect of the long wavelength cutoff (λc) filter is that values near
the edge of the evaluation length or area are skewed. To prevent
these skewed values from affecting 2D and 3D parameter
calculations, the values near the edges of the evaluation are
discarded. The Discard length is calculated from the long wavelength
cutoff (λc) selected.
The following discard selections are available:
Discard none
Discard ½
Discard 1
2D Orientation
2D parameters are calculated from a virtual 'trace' across the image
area. By default, this trace is in the Horizontal X direction, parallel to
the long axis of the replica tape. This orientation can be changed if
desired:
Horiz X (Horizontal X)
Vert Y (Vertical Y)
Diag XY (Diagonal XY)
Diag YX (Diagonal YX)
(default)
(default)
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