NAME
median3d - running window smoothing (median) of 3D data.
SYNOPSIS
median3d [ -N file_in ] [ -AMEDIAN file_out ] [ -tstart
tstart ] [ -tskip tskip ] [ -tend tend ] [ -apheight
apheight ] [ -apwidth apwidth ] [ -aplength aplength ] [
-ildm ildm ] [ -cldm cldm ] [ -fdead ] [ -? ]
DESCRIPTION
median3d reads in 3D seismic post stack data and smooths it
using a simple median. A 3D subcube moves through a 3D pro-
cess cube where the 3D process cube can be specified to con-
sist of certain portions of the input data cube. The median
of sample (i,j,k) is derived from all samples in the sur-
rounding window bounded by (i-iap to i+iap), (j-jap to
j+jap) and (k-kap to k+kap).
USAGE
median3d gets all its parameters from command line argu-
ments. These arguments specify the input and output, the
sample points of each trace you want to use for processing
(specified by tstart, tskip and tend), the running window
dimensions (specified by apheight, aplength and apwidth),
the in-line/cross-line spacing of the dataset, as well as an
option that lets you decide wether you want to include
median values calculated for dead traces in the output or
not.
Command line arguments
-N file_in
Enter the input data set name or file immediately after
typing -N. The file is not required when receiving
piped input from another process. The input file
should include the complete path name if the file
resides in a different directory. For this program,
the data must be stored as a rectangular grid of regu-
larly binned data. The number of traces denoted by
lineheader word 'NumTrc' defines the number of traces
in the x-direction. The number of records (seismic
lines) denoted by lineheader word 'NumRec' defines the
number of traces in the y-direction. Missing data
should be padded in with dead traces flagged by the
dead trace header flag 'StaCor'=30000.
-AMEDIAN file_out
Enter the output median data set file name immediately
after typing -AMEDIAN. This output file is not
required when piping the output to another process.
The output data set also requires the full path name
(see above).
tstart, tskip and tend can be used to select a reduced set
of sample points (per trace) of the whole input data set.
Note that the times that you specify will be internaly
adjusted to fit the time grid of the existing data. All
times have to be given and will be set in milliseconds,
respectively. Note that tend has to be greater than tstart;
otherwise error message will occur.
-tstart tstart
Specifies the time of occurence of first sample point
in trace which will be used for processing. Will be
adjusted internaly according to the following rules:
default => TmMsFs (time of occurence of first sample
point in trace)
if tstart specified is less than or equal to TmMSFs =>
set tstart internaly to TmMsFs
if tstart specified is greater than TmMSFs => set
tstart internaly to the time of occurence of the next
available sample whose time of occurence is greater or
equal to tstart specified
if tstart specified is greater than the time of
occurence of the last sample in the trace => set tstart
internaly to time of occurence of last sample in trace
-tskip tskip
Specifies the time increment for the selection of trace
sample points used for processing. Will be adjusted
internaly according to the following rules:
default => one input sample interval
if tskip specified is less than or equal to zero => set
tskip internaly to one input sample interval
if tskip specified is greater than zero => set tskip
internaly to the multiple of input sample intervals it
encloses
if tskip specified is greater than the difference
between the time of occurence of the last sample point
in a trace and the first sample point in a trace => set
tskip internaly to this time difference
-tend tend
Specifies the time of occurence of last sample point in
trace which will be used for processing. Will be
adjusted internaly according to the following rules:
default => time of occurence of last sample point in
trace
if tend specified is less than or equal to TmMSFs =>
set tend internaly to the time of occurence of last
sample in trace
if tend specified is greater than TmMSFs => set tend
internaly to the time of occurence of the last avail-
able sample whose time of occurence is smaller or equal
to tend specified
if tend specified is greater than the time of occurence
of last sample in trace => set tend internaly to time
of occurence of last sample in trace
apheight, aplenght and apwidth can be used to select the
size of the running window used for processing. Note that
the units that you specify will be internaly adjusted to fit
the units of the existing data.
-apheight apheight
Enter the half aperture height of the running window in
msec. Will be adjusted internaly according to the fol-
lowing rules:
default = 3 * internaly used tskip (see tskip)
if apheight specified is less than or equal to inter-
naly used tskip => set apheight internaly to internaly
used tskip
if apheight specified is greater than internaly used
tskip => set apheight internaly to the multiple of
internaly used tskip it encloses
-aplength aplength
Enter the half aperture length of the running window in
m or ft. Will be adjusted internaly according to the
following rules:
default = 3 * ILClIn (In-line cell increment)
if aplength specified is less than or equal to ILClIn
=> set aplength internaly to ILClIn
if aplength specified is greater than ILClIn => set
aplength internaly to the multiple of ILCLIn it
encloses
-apwidth apwidth
Enter the half aperture width of the running window in
m or ft. Will be adjusted internaly according to the
following rules:
default = 3 * CLClIn (Cross-line cell increment)
if apwidth specified is less than or equal to CLClIn =>
set apwidth internaly to CLClIn
if apwidth specified is greater than CLClIn => set
apwidth internaly to the multiple of CLClIn it encloses
-ildm ildm
If not found in the line header, you must specify the
in-line spacing (In-line cell increment)
-cldm cldm
If not found in the line header, you must specify the
crossline spacing (Cross-line cell increment)
-fdead
Enter the command line argument '-fdead' to fill dead
traces. If not specified the mean obtained from points
where the midpoint of the running cube falls into a
dead trace will be set to zero. If specified the mean
obtained from points where the midpoint of the running
cube falls into a dead trace will be included in the
output if more than 50% of all data points in the run-
ning cube are due to live traces. This option can
therefore be used to fill (interpolate) sections of the
data set where some dead traces exist within a majority
of live traces.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
BUGS
None currently known.
See Also:
stat3d, c2p6, c3p6, SSAM, lm3dvtosis, sistolm3dv,
iesx3dtosis, iesx3dtosis, flowmaker
REFERENCES:
Marfurt, Kurt J., Sudhakar, V., Gersztenkorn, Adam, Craw-
ford, Kelly D., Nissen, Susan E., 1997, "Coherency Calcula-
tions in the Presence of Structural Dip", Geoscience Tech-
nology Bulletin, F97-G-11 (970290002-TUL).
CONTRACT AGREEMENT
This product is brought to you by Research Contract Agree-
ment 548 (Seismic coherency cube). Thank you for your
support.
AUTHOR
Bertram Kaufhold (1998)
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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