seismic.convolve {RGeostats}R Documentation

Convolute the seismic attributes

Description

Perform convolution of the seismic attributes

Usage

seismic.convolve(db, type = 0, ntw = 5, 
option = 0, tindex = 0, fpeak = 1, 
period = 1, amplitude = 1, distort = 0, 
flag.operate = TRUE, flag.contrast = FALSE, 
wavelet = NA, val.before=0., val.middle=0., 
val.after=0., radix = "Convolve", modify.target = db.locmod())

Arguments

db

The db-class containing the seismic attributes to be convoluted

type

Type of convolution

  • 0 : No convolution

  • 1 : Ricker-1 Wavelet (peak)

  • 2 : Ricker-2 Wavelet (period, amplitude & distortion)

  • 3 : Wavelet Alford, Kelly and Boore (peak & amplitude)

  • 4 : Spike (tindex)

  • 5 : Constant unit shift

  • -1 : Wavelet defined by the user as input argument

ntw

Number of samples in the half-length of the wavelet excluding the center. If the wavelet is provided (type<0), this parameter is calculated automatically.

option

Egde processing option:

  • -1 : The output trace is eroded (first and last ntw values along the trace)

  • 0 : The wavelet is truncated to the edge of the field

  • +1 : The wavelet is extended by ntw pixels. Then the convolution takes place and the result is truncated back to the initial length of the trace.

  • +2 : The wavelet is extended by ntw pixels. Each extension is set to the value of the first (resp. last) pixel of the initial trace.

tindex

Time index to locate the spike

fpeak

Peak frequency of the Ricker and AKB wavelets (f)

period

Wavelet period for Ricker wavelets (λ)

amplitude

Wavelet amplitude for Ricker & AKB wavelets (α)

distort

Wavelet distortion factor for Ricker wavelet (β)

flag.operate

When TRUE, the convolution is performed (the output is the modified Db). When FALSE, the discretized wavelet is printed out (no additional output is provided)

flag.contrast

When TRUE, the initial value is first converted into a contrast before convolution.

wavelet

Array containing the discretized wavelet used when type=-1. Its dimension must be 2*ntw+1.

val.before

Assigned to undefined values of each trace before the first defined sample

val.middle

Assigned to undefined values of each trace between two defined samples

val.after

Assigned to undefined values of each trace after the last defined sample

radix

Radix of the name given to the variables storing the results in the target Db.

modify.target

Decides whether or not the newly created variables will have their locator defined or not. For more information, see db.locmod.

Details

The Ricker-1 wavelet equation is:

w(t) = ( 1 - 2 * (π*f*dt*(t-t0))^2 ) / exp[ -(π*f*dt*(t-t0))^2 ]

The Ricker-2 wavelet equation is:

w(t) = α * (1 - 2 * ( 2.5 * dt*(t-t0)/λ)^2 ) / exp[ -(2.5 * dt*(t-t0)/λ)^2 ] * ( 1 - 2 * β * dt*(t-t0)/λ )

The Alford, Kelly and Boore wavelet equation is:

w(t) = -α * (t-t0) * exp[- 2 * (f*dt*(t-t0))^2]

with:

Value

The output Db with as many output variables as there are seismic attributes in the input Db.

See Also

seismic.grid.define seismic.convert seismic.operate


[Package RGeostats version 11.0.6 Index]