NAME
radonr - generalized discrete radon inverse transform from
(tau,p) to (t,x) domain.
SYNOPSIS
radonr [ -Nntap ] [ -Ootap ] [ -dmindmin ] [ -dmaxdmax ] [
-dxdx ] [ -Slensmooth ] [ -Mamaxmem ] [ -I ] [ -Y ] [
-nomute ] [ -R ] [ -? ]
DESCRIPTION
radonr takes the generalized discrete radon transform domain
(tau,p) gathers generated by routine radonf and transforms
them back to the conventional (t,x) domain data at either
the original trace locations, or (optionally) at a new regu-
lar grid of surface locations.
INPUT: Common shot, common receiver or common midpoint
(tau,p) domain gathers, or running window stack or common
offset gathers run through routine rwindow. OUTPUT:
Corresponding gathers in (t,x) domain.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N unless the input is from a pipe in which case
the -N entry must be omitted. This input file should
include the complete path name if the file resides in a
different directory. Example -N/b/vsp/dummy tells the
program to look for file 'dummy' in directory '/b/vsp'.
-O otap
Enter the output data set name or file immediately
after typing -O. 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).
-dmin dmin
Minimum signed trace distance (ft or m) of the output
regularized data. (Default: calculate output at origi-
nal trace locations).
-dmax dmax
Maximum signed trace distance (ft or m) of the output
regularized data. (Default: calculate output at origi-
nal trace locations).
-dx dx
Trace increment (ft or m) of the output regularized
data. If all three arguments dmin,dmax,dx are
detected, the data will be regularized. (Default: cal-
culate output at original trace locations).
-S lensmooth
Perform median filter smoothing of the early mutes dur-
ing reconstruction using a lensmooth point median
filter. (will tend to infill ragged shallow data in
poststack data). (Default, lensmooth=0 or no smooth-
ing).
-M amaxmem
Enter the maximum memory allowed for the program in
Megawords. The program will try to store as many radon
transform matrices in memory as will fit, thereby eli
minating the need to recompute them for the same
source-receiver distances in su bsequent gathers.
(Default: amaxmem=32 Megawords on the Crays, amaxmem=4
Megawords on the Sparcs).
-I Enter the command line -I to interpolate dead traces at
the original signed trace distances DstSgn (assumed to
be correct! make sure that DstSgn is not zero!).
-R Enter the command line -R to generate regularized data.
See note below!
-Y Enter the command line -Y to reconstruct data data in
the y direction.
-nomute
Enter the command line -nomute to NOT restore the early
mute.
-V Enter the command line argument '-V' to get additional
printout.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
NOTE 1:
Data that have been regularized to a different shot-receiver
increment than the original data will have correct trace
numbers and trace distances, but incorrect record indices,
thereby requiring the user to reindex the data using USP
programs maip, laip, pr3d or script ufh. Regularization to
equally spaced shots can be acheived by sorting the data to
common receiver domain and running radonf|radonr -R there.
NOTE 2:
The user should contemplate flows such as radonf
-L|polymute|radonr -R; sisort -G; radonf -L|polymute|radonr
-R for effective, consistent filtering and interpolation of
irregularly sampled data onto a regular grid. The flow
fft2da|polymute|fft2da -R ; sisort -G
;fft2da|polymute|fft2da -R is significantly more efficient
and should be tried first on regularly sampled data with
strong linear noise trains.
NOTE 3 (STOLEN HEADERS):
In order to apply discrete radon transform filtering to 3D
post stack or 3D common offset data, several trace headers
need to be stolen. Considerable care was taken not to steal
commonly used header words. Nevertheless, certain collisions
may occur for flows unforseen by the author. Future plans
call for using the dds system, which will ameli orate the
line header problem.
Line header words stolen by radonf and radonr when transform is in the inline direction (including normal shot gather, receiver gather and cmp gather transforms):
Header keyword variable
Crew01 't'
Crew02 'p'
Crew03 moveout ('L','P',or 'H')
MnUHTm ntr (number of input traces)
MxUHTm nfft (length of FFT)
TmMsFS f1
MutVel f4
NmSpMi df
MxRSEL zref
MnGrEl mmin
MxGrEl mmax
MxTrOf xmax
MxTrSt ist
Trace header words stolen by radonf and radonr for transform in the
inline direction:
DstUsg p*dt*1.e+07 (for use in routine taupred)
TVPT20 and TVPV20 p (as a floating point for use in routine mute3D)
TVPT19 x (inline distance as found in input word DstSgn)
MulSkw muteend (first non-zero sample of input data used to re
store early mute)
StaCor dead trace flag 30000 changed to 30001
transform of dead trace flag 30001 changed to 30002
this allows pred and taupred to work
operation reversed on inverse transform
Line header words stolen by radonf and radonr for transform in the fIcrossline direction
invoked by using the -Y option above:
Header keyword variable
Crew01 't'
Crew04 'q'
Crew05 moveout ('L','P',or 'H')
MnShDp ntr (number of input traces)
MxShDp nfft (length of FFT)
TmMsSl f1*1.e+06
TmSlIn f4*1.e+06
AERcPr df*1.e+06
IndAdj zref
MnSPEl mmin
MxSPEl mmax
MnTrOf xmax
MnTrSt ist
Trace header words stolen by radonf and radonr for transform in the
crossline direction:
DstUsg q*dt*1.e+07 (for use in routine taupred)
TVPT21 and TVPV21 q (as a floating point for use in routine mute3D)
TVPV19 y (crossline distance as found in input word DstSgn)
PREPIn muteend (first non-zero sample of input data used to re
store early mute)
StaCor dead trace flag 30000 changed to 30001
transform of dead trace flag 30001 changed to 30002
this allows pred and taupred to work
operation reversed on inverse transform
Line header words stolen by rwindow in generating running window in the inline direction
(default mode in rwindow):
Header keyword variable
RATFld npad
OpGrFl nline (number of lines in the inline direction)
OrNREC nrec_inline (number of inline windowed records)
OrNTRC ntrpline (number of inline traces of original unwindowe
d line)
RATTrc ntrcumpads (ntr+2*npad)
Line header words stolen by rwindow in generating running window in the crossline direction
(invoked by using the -Y option in rwindow):
Header keyword variable
FrstSP npad
DpN1SP nline (number of lines in the crossline direction)
NmDpIn nrec_inline (number of crossline windowed records)
NTrLnS ntrpline (number of crossline traces of original unwind
owed line)
StWdFl ntrcumpads (ntr+2*npad)
NOTE 4:
If the line header value SmpInt>16, it is assumed to be in
microseconds rather than in milliseconds.All command line
arguments are considered to be in millseconds.
REFERENCES
Belykin, G. (1987) Discrete Radon Transforms, IEEE Transac-
tions on Acoustics, Sp eech and Signal Processing, Vol
ASSP-35, No. 2, p162-172.
Kabir, N. and Verschuur, E. (1993) The use of parabolic
radon transforms in preprocessing; Delphi Consortium Report,
Vol IV, T.U. Delft, Delft, the Netherlands.
BUGS
No bugs known at present.
SEE ALSO
radonf,polymute,taupred,rmmult,taupf,taupr,slstkf,slstkr
AUTHOR
Kurt J. Marfurt (1992). Built upon earlier work in routine
rmmult. 3D common offset and post stack capabilities added
12/93.
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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