R: Convolute the seismic attributes

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:

w(t) : Wavelet equation
dt : Grid mesh along the vertical axis
t0 : Center of the wavelet

Value