Directional Pass/Reject (DPAS)

Use the Directional Pass/Reject option to apply a directional pass/reject filter.

Directional Pass/Reject Filter dialog options

Starting cut-off azimuth)

The low cut-off angle in degrees azimuth, in space domain (geological strike). Note that this angle is 90 degree different from the k₀ (see figure below) in frequency domain. ( = k₀-90.0)

Ending cut-off azimuth)

The high cut-off angle in degrees azimuth, in space domain (geological strike). Note that this angle is 90 degree different from the k₁ (see figure below) in frequency domain. ( = k₁-90.0)

Pass

Reject

Select "Pass" or "Reject" (Default is to pass the band).

Application Notes

Directional pass/reject filter

$image\ebx_270281707.jpg$

Parameters:

k₀	the low cut-off angle in degrees azimuth (from North).
k₁	the high cut-off angle in degrees azimuth (from North).
	0/1 if 1, pass the defined band; if 0, reject the defined band. The default is to pass the band.

As with the bandpass filter, the directional-pass often suffers from Gibb's Phenomena ringing because the spectrum is cut so abruptly. We recommend using the directional cosine filter (DCOS) instead.

Wavenumber domain variable definition


k	Wavenumber domain increment, used to depict a radially symmetrical variable.	where: np is the number of points cs is the cell size
u	X component in the wavenumber domain.	k = 2π ( i μ+j ν )
v	Y component in the wavenumber domain.
r	Radial component in the wavenumber domain.	also 2πk
θ	Polar component in the wavenumber domain.